Re: final drying of mirror before coating
Can't find any pix after an extensive 9-second search. Will take some later on this week.
? Guy Brandenburg, Washington, DC? My blog, mostly on Education in DC:
My home page on astronomy, mathematics, education: or else ?? =====================================
From: "Aurigema, Andrew N. (KSC-ASRC-474)[Not Assigned]"
To: "VacuumX@..."
Sent: Mon, October 25, 2010 11:05:41 AM
Subject: RE: [VacuumX] final drying of mirror before coating
?
Guy,
?
I have found that to get rid of really stubborn contamination
you may need a wet wipe with a little CeO and using very gentle pressure on a wet
cotton rag.? A few circular wipes around the ( wet ) mirror can get rid of
many pesky residues. ?
?
I tend to burn my tungsten emitters a little hot and I don¡¯t
have the best vacuum so some tungsten oxides are transmitted to the
mirrors.? This prints thru as streaks in the aluminum some times.?
The muriatic acid and copper sulfate stripper I use will not remove this kind
of metal vapor residue.? It takes Calcium carbonate or Cerium oxide or jewelers
rouge to get it off the mirror¡¯s surface.?
?
I clean with 91% IPA ( but most people recommend 100% reagent
grade methyl alcohol ) ?and a final pass with just a spray of vapor of Windex
on white paper towel and I close the door on my chamber.?
?
How big is your chamber???? Any pics of it ???
?
Drew in sunny Florida
?
?
From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of Guy
Brandenburg
Sent: Friday, October 22, 2010 11:09 PM
To: VacuumX@...
Subject: [VacuumX] final drying of mirror before coating
?
?
How do you perform your final
mirror-drying operation before putting that sucker into your backyard or
basement vacuum chamber?
In our plain-vanilla
mirror-coating operation at the NCA-CCCC telescope-making and mirror-coating
and nose-picking workshop here in DC, which I 'inherited' from a previous
leader, I think that I am finding recently that there is some sort of weird
residue on sections of a number of newly coated mirrors - coated by us.?
I suspect that it seems to
come off of paper towels - at least some brands of them, I suspect.
Unfortunately, I have not done a systematic evaluation to see if this is true,
and the conditions are always just a little bit different every time I coat or
re-coat a mirror. So I am really not sure on this at all, one way or the other.
I have no idea whether it's the final rinsing that's inadequate, or if it's
something in certain brands and varieties of paper towels themselves, or
something else. I avoid types that advertize hand-softeners or anything like
that. Sometimes I wonder whether I forgot and blew my nose on the paper towels
first. Or maybe the Green River wasn't mixed properly. Or perhaps these mirrors
just have cooties?Or perchance the ion bombardment (aka glow discharge) wasn't
long enough. Or I'm just an idiot. Etcetera. In any case, I don't recall seeing
it much before, and it seems to be getting worse. (but even that data point is
suspect.)
BTW, the setup that we have
is something that was scrounged together from 1950-to-1960-era US government
surplus equipment coupled with a variety of modifications and improvements that
were crafted by my predecessors, or donated by others. My predecessors are
mostly either deceased or are in poor health. We do this aluminization for
purely nominal fees that allow us to buy some more pitch and grit and glass.
(The
mirrors are certainly usable, but they are not elegantly clean like I would
prefer. You can see thin, dusty streaks when you look at the mirror at certain
angles.?I know, I know, I should have taken a picture. Will do so.
(But
the workshop location is clear on the other side of town. And when I'm there,
unless I go on off-hours, there are always lots of folks building telescopes at
one level or another, and they all have questions or need advice. So I don't
get to do much for myself. And they are closed on Sundays, and normal closing
time is 10 PM.)
I have read and heard of lots
of ways of doing this final drying, including distilled water blown off by
compressed nitrogen; pure ethanol; pure this, pure that, microfibers, and more.
?
What methods are preferred by
the present readership?
?
Guy Brandenburg, Washington, DC?
My
blog, mostly on Education in DC:
?
My
home page on astronomy, mathematics, education:
or else ??
=====================================
?
|
Re: final drying of mirror before coating [2 Attachments]
Hmm. Mine doesn't seem to look like that. Have had zero problems with cooling of oil and so on.? I could be wrong.? WIll coat a mirror in the next couple of days and take photos.? AND I will use a different brand of paper towel, too.
? Guy Brandenburg, Washington, DC? My blog, mostly on Education in DC:
My home page on astronomy, mathematics, education: or else ?? =====================================
From: "Aurigema, Andrew N. (KSC-ASRC-474)[Not Assigned]"
To: "VacuumX@..."
Sent: Mon, October 25, 2010 11:24:52 AM
Subject: RE: [VacuumX] final drying of mirror before coating [2 Attachments]
?
Guy,
?
?
I attached a picture ( build 248) of what oil vapor back
streaming looks like in my chamber.? The water got turned off to the coolant
jackets and the thermal override did not kick in.? The oil seems to have mapped
to the last cleaning swipe pattern I used on the mirror.? The mirror was very
clean before the door was closed.? It got contaminated by the oil vapor during
the pump down.?
?
Picture (build 350) shows some kind of pesky contamination that
stripper and calcium carbonate did not remove.? It took cerium oxide to get
that off the mirror.? I think it was residue from my previous years coating as
it was not there the year before ( having just come from Lockwood¡¯s shop where
it got a fresh new figure ).
?
Maybe your contamination is occurring after your closing of the
door like mine was.?
?
Drew in sunny Florida
?
From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of Guy
Brandenburg
Sent: Saturday, October 23, 2010 11:51 AM
To: VacuumX@...
Subject: Re: [VacuumX] final drying of mirror before coating
?
?
Vladimir,
Neither the type of glass, nor the date of the last polishing, nor the vacuum
level, nor the oil seem to me to be the source of the problem.
We clean the glass, which is generally (but not always) Pyrex by first using
Green River (ie HCl and CuSO4) on paper towels to remove the old coating (if
there was one); then bare fingers and lukewarm water and detergent without
perfumes or oils; then cotton balls and lukewarm water and detergent; then
rinse with lukewarm water and cotton balls; then scrub with a slurry of
powdered calcium carbonate USP and water and cotton balls; then rinse with warm
water and cotton balls; and repeat all of the above until we can see, with our
eyes, that there are no 'drops' of water on the surface of the glass and that
the water forms a single sheet with no imperfections.
Then we dry it off with numerous paper towels.
After loading the glass into the chamber, but right before we close it up, we
generally spray the surface a glancing blow with some compressed air in a can,
not previously shaken, and held horizontally, through a tube, supposedly to get
rid of any dust particles. (It's not like we have a clean room or anything.
Quite the contrary!) And we always do the ion bombardment/glow discharge for
about 30 minutes with ambient air; no change there. It's easy to see the aurora
vacuumalis inside the chamber. Quite pretty, especially witrh the other lights
turned off.
Some of the glass has been finished being figured only a day or so before being
aluminized. Some, a couple of weeks. Some of it was finished figuring many
years ago and then we strip off the old coating.
I am more and more thinking it has something to do with the chemical
composition of the towels. The ones we are using at the moment are Safeway's
home brand, and advertise that they are more absorbent than usual. (Of course,
they all say that.)
I am considering using well-laundered and dried old cotton rags instead of
paper towels (no fabric softener, of course), for the final cleaning. Anybody
else out there use that?
?
Guy Brandenburg, Washington, DC
My blog, mostly on Education in DC:
?
My home page on astronomy, mathematics, education:
or else ??
=====================================
?
From: Vladimir Chutko
To: VacuumX@...
Sent: Fri, October 22, 2010 8:54:38 PM
Subject: Re: [VacuumX] final drying of mirror before coating
?
Hi Guy,
There are too many possible causes of that "weird residue": old glass
surface, bad cleaning (both wrong materials and bad hands), bad vacuum quality,
wrong ion cleaning.... What kind of glass do you use? What is a time gap
between polishing and coating? A regular? cleaning with alcohol or acetone
using special paper napkins (I can give you a brand next week) or just washed
fat free cotton ones usually provide a surface well suitable for Al coating. Of
coarse, glow discharge or ion beam pre-cleaning in vacuum is necessary. If you
use glow discharge, a working gas actually doesn't matter, you can use even
air; if you use ion source, gases (Ar, O2, N, or their mixes) must be very
pure. And vacuum quality - oil free ultimate vacuum about 10-5 torr required.
The source(s) of those defects may be in any process step. It is hard to
discuss without detailed information about all of them....
Regards,
Vladimir Chutko
On 10/22/2010 8:09 PM, Guy Brandenburg wrote:
How
do you perform your final mirror-drying operation before putting that sucker
into your backyard or basement vacuum chamber?
In
our plain-vanilla mirror-coating operation at the NCA-CCCC telescope-making and
mirror-coating and nose-picking workshop here in DC, which I 'inherited' from a
previous leader, I think that I am finding recently that there is some sort of
weird residue on sections of a number of newly coated mirrors - coated by
us.?
I
suspect that it seems to come off of paper towels - at least some brands of
them, I suspect. Unfortunately, I have not done a systematic evaluation to see
if this is true, and the conditions are always just a little bit different
every time I coat or re-coat a mirror. So I am really not sure on this at all,
one way or the other. I have no idea whether it's the final rinsing that's
inadequate, or if it's something in certain brands and varieties of paper
towels themselves, or something else. I avoid types that advertize
hand-softeners or anything like that. Sometimes I wonder whether I forgot and
blew my nose on the paper towels first. Or maybe the Green River wasn't mixed
properly. Or perhaps these mirrors just have cooties?Or perchance the ion
bombardment (aka glow discharge) wasn't long enough. Or I'm just an idiot.
Etcetera. In any case, I don't recall seeing it much before, and it seems to be
getting worse. (but even that data point is suspect.)
BTW,
the setup that we have is something that was scrounged together from
1950-to-1960-era US government surplus equipment coupled with a variety of
modifications and improvements that were crafted by my predecessors, or donated
by others. My predecessors are mostly either deceased or are in poor health. We
do this aluminization for purely nominal fees that allow us to buy some more
pitch and grit and glass.
(The mirrors are certainly usable, but they are
not elegantly clean like I would prefer. You can see thin, dusty streaks when
you look at the mirror at certain angles.?I know, I know, I should have
taken a picture. Will do so.
(But the workshop location is clear on the other
side of town. And when I'm there, unless I go on off-hours, there are always
lots of folks building telescopes at one level or another, and they all have
questions or need advice. So I don't get to do much for myself. And they are
closed on Sundays, and normal closing time is 10 PM.)
I
have read and heard of lots of ways of doing this final drying, including
distilled water blown off by compressed nitrogen; pure ethanol; pure this, pure
that, microfibers, and more. ?
What
methods are preferred by the present readership?
?
Guy Brandenburg,
Washington, DC?
My blog, mostly on Education in DC:
?
My home page on astronomy, mathematics, education:
or else ??
=====================================
?
?
|
Re: final drying of mirror before coating
Aurigema, Andrew N. (KSC-ASRC-474)[Not Assigned]
Guy,
?
?
I attached a picture ( build 248) of what oil vapor back
streaming looks like in my chamber.? The water got turned off to the coolant
jackets and the thermal override did not kick in.? The oil seems to have mapped
to the last cleaning swipe pattern I used on the mirror.? The mirror was very
clean before the door was closed.? It got contaminated by the oil vapor during
the pump down.?
?
Picture (build 350) shows some kind of pesky contamination that
stripper and calcium carbonate did not remove.? It took cerium oxide to get
that off the mirror.? I think it was residue from my previous years coating as
it was not there the year before ( having just come from Lockwood¡¯s shop where
it got a fresh new figure ).
?
Maybe your contamination is occurring after your closing of the
door like mine was.?
?
Drew in sunny Florida
?
From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of Guy
Brandenburg
Sent: Saturday, October 23, 2010 11:51 AM
To: VacuumX@...
Subject: Re: [VacuumX] final drying of mirror before coating
?
?
Vladimir,
Neither the type of glass, nor the date of the last polishing, nor the vacuum
level, nor the oil seem to me to be the source of the problem.
We clean the glass, which is generally (but not always) Pyrex by first using
Green River (ie HCl and CuSO4) on paper towels to remove the old coating (if
there was one); then bare fingers and lukewarm water and detergent without
perfumes or oils; then cotton balls and lukewarm water and detergent; then
rinse with lukewarm water and cotton balls; then scrub with a slurry of
powdered calcium carbonate USP and water and cotton balls; then rinse with warm
water and cotton balls; and repeat all of the above until we can see, with our
eyes, that there are no 'drops' of water on the surface of the glass and that
the water forms a single sheet with no imperfections.
Then we dry it off with numerous paper towels.
After loading the glass into the chamber, but right before we close it up, we
generally spray the surface a glancing blow with some compressed air in a can,
not previously shaken, and held horizontally, through a tube, supposedly to get
rid of any dust particles. (It's not like we have a clean room or anything.
Quite the contrary!) And we always do the ion bombardment/glow discharge for
about 30 minutes with ambient air; no change there. It's easy to see the aurora
vacuumalis inside the chamber. Quite pretty, especially witrh the other lights
turned off.
Some of the glass has been finished being figured only a day or so before being
aluminized. Some, a couple of weeks. Some of it was finished figuring many
years ago and then we strip off the old coating.
I am more and more thinking it has something to do with the chemical
composition of the towels. The ones we are using at the moment are Safeway's
home brand, and advertise that they are more absorbent than usual. (Of course,
they all say that.)
I am considering using well-laundered and dried old cotton rags instead of
paper towels (no fabric softener, of course), for the final cleaning. Anybody
else out there use that?
?
Guy Brandenburg, Washington, DC
My blog, mostly on Education in DC:
?
My home page on astronomy, mathematics, education:
or else ??
=====================================
toggle quoted message
Show quoted text
From: Vladimir Chutko
<chutko@...>
To: VacuumX@...
Sent: Fri, October 22, 2010 8:54:38 PM
Subject: Re: [VacuumX] final drying of mirror before coating
?
Hi Guy,
There are too many possible causes of that "weird residue": old glass
surface, bad cleaning (both wrong materials and bad hands), bad vacuum quality,
wrong ion cleaning.... What kind of glass do you use? What is a time gap
between polishing and coating? A regular? cleaning with alcohol or acetone
using special paper napkins (I can give you a brand next week) or just washed
fat free cotton ones usually provide a surface well suitable for Al coating. Of
coarse, glow discharge or ion beam pre-cleaning in vacuum is necessary. If you
use glow discharge, a working gas actually doesn't matter, you can use even
air; if you use ion source, gases (Ar, O2, N, or their mixes) must be very
pure. And vacuum quality - oil free ultimate vacuum about 10-5 torr required.
The source(s) of those defects may be in any process step. It is hard to
discuss without detailed information about all of them....
Regards,
Vladimir Chutko
On 10/22/2010 8:09 PM, Guy Brandenburg wrote:
How
do you perform your final mirror-drying operation before putting that sucker
into your backyard or basement vacuum chamber?
In
our plain-vanilla mirror-coating operation at the NCA-CCCC telescope-making and
mirror-coating and nose-picking workshop here in DC, which I 'inherited' from a
previous leader, I think that I am finding recently that there is some sort of
weird residue on sections of a number of newly coated mirrors - coated by
us.?
I
suspect that it seems to come off of paper towels - at least some brands of
them, I suspect. Unfortunately, I have not done a systematic evaluation to see
if this is true, and the conditions are always just a little bit different
every time I coat or re-coat a mirror. So I am really not sure on this at all,
one way or the other. I have no idea whether it's the final rinsing that's
inadequate, or if it's something in certain brands and varieties of paper
towels themselves, or something else. I avoid types that advertize
hand-softeners or anything like that. Sometimes I wonder whether I forgot and
blew my nose on the paper towels first. Or maybe the Green River wasn't mixed
properly. Or perhaps these mirrors just have cooties?Or perchance the ion
bombardment (aka glow discharge) wasn't long enough. Or I'm just an idiot.
Etcetera. In any case, I don't recall seeing it much before, and it seems to be
getting worse. (but even that data point is suspect.)
BTW,
the setup that we have is something that was scrounged together from
1950-to-1960-era US government surplus equipment coupled with a variety of
modifications and improvements that were crafted by my predecessors, or donated
by others. My predecessors are mostly either deceased or are in poor health. We
do this aluminization for purely nominal fees that allow us to buy some more
pitch and grit and glass.
(The mirrors are certainly usable, but they are
not elegantly clean like I would prefer. You can see thin, dusty streaks when
you look at the mirror at certain angles.?I know, I know, I should have
taken a picture. Will do so.
(But the workshop location is clear on the other
side of town. And when I'm there, unless I go on off-hours, there are always
lots of folks building telescopes at one level or another, and they all have
questions or need advice. So I don't get to do much for myself. And they are
closed on Sundays, and normal closing time is 10 PM.)
I
have read and heard of lots of ways of doing this final drying, including
distilled water blown off by compressed nitrogen; pure ethanol; pure this, pure
that, microfibers, and more. ?
What
methods are preferred by the present readership?
?
Guy Brandenburg,
Washington, DC?
My blog, mostly on Education in DC:
?
My home page on astronomy, mathematics, education:
or else ??
=====================================
?
?
|
Re: final drying of mirror before coating
Aurigema, Andrew N. (KSC-ASRC-474)[Not Assigned]
Guy,
?
I have found that to get rid of really stubborn contamination
you may need a wet wipe with a little CeO and using very gentle pressure on a wet
cotton rag.? A few circular wipes around the ( wet ) mirror can get rid of
many pesky residues. ?
?
I tend to burn my tungsten emitters a little hot and I don¡¯t
have the best vacuum so some tungsten oxides are transmitted to the
mirrors.? This prints thru as streaks in the aluminum some times.?
The muriatic acid and copper sulfate stripper I use will not remove this kind
of metal vapor residue.? It takes Calcium carbonate or Cerium oxide or jewelers
rouge to get it off the mirror¡¯s surface.?
?
I clean with 91% IPA ( but most people recommend 100% reagent
grade methyl alcohol ) ?and a final pass with just a spray of vapor of Windex
on white paper towel and I close the door on my chamber.?
?
How big is your chamber???? Any pics of it ???
?
Drew in sunny Florida
?
?
From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of Guy
Brandenburg
Sent: Friday, October 22, 2010 11:09 PM
To: VacuumX@...
Subject: [VacuumX] final drying of mirror before coating
?
?
How do you perform your final
mirror-drying operation before putting that sucker into your backyard or
basement vacuum chamber?
In our plain-vanilla
mirror-coating operation at the NCA-CCCC telescope-making and mirror-coating
and nose-picking workshop here in DC, which I 'inherited' from a previous
leader, I think that I am finding recently that there is some sort of weird
residue on sections of a number of newly coated mirrors - coated by us.?
I suspect that it seems to
come off of paper towels - at least some brands of them, I suspect.
Unfortunately, I have not done a systematic evaluation to see if this is true,
and the conditions are always just a little bit different every time I coat or
re-coat a mirror. So I am really not sure on this at all, one way or the other.
I have no idea whether it's the final rinsing that's inadequate, or if it's
something in certain brands and varieties of paper towels themselves, or
something else. I avoid types that advertize hand-softeners or anything like
that. Sometimes I wonder whether I forgot and blew my nose on the paper towels
first. Or maybe the Green River wasn't mixed properly. Or perhaps these mirrors
just have cooties?Or perchance the ion bombardment (aka glow discharge) wasn't
long enough. Or I'm just an idiot. Etcetera. In any case, I don't recall seeing
it much before, and it seems to be getting worse. (but even that data point is
suspect.)
BTW, the setup that we have
is something that was scrounged together from 1950-to-1960-era US government
surplus equipment coupled with a variety of modifications and improvements that
were crafted by my predecessors, or donated by others. My predecessors are
mostly either deceased or are in poor health. We do this aluminization for
purely nominal fees that allow us to buy some more pitch and grit and glass.
(The
mirrors are certainly usable, but they are not elegantly clean like I would
prefer. You can see thin, dusty streaks when you look at the mirror at certain
angles.?I know, I know, I should have taken a picture. Will do so.
(But
the workshop location is clear on the other side of town. And when I'm there,
unless I go on off-hours, there are always lots of folks building telescopes at
one level or another, and they all have questions or need advice. So I don't
get to do much for myself. And they are closed on Sundays, and normal closing
time is 10 PM.)
I have read and heard of lots
of ways of doing this final drying, including distilled water blown off by
compressed nitrogen; pure ethanol; pure this, pure that, microfibers, and more.
?
What methods are preferred by
the present readership?
?
Guy Brandenburg, Washington, DC?
My
blog, mostly on Education in DC:
?
My
home page on astronomy, mathematics, education:
or else ??
=====================================
?
|
Re: final drying of mirror before coating
Vladimir,
Could you tell me the purity degree or lever the O2 and Ar gas you use!
Thank's!
Attila
The Hun
toggle quoted message
Show quoted text
--- In VacuumX@..., Vladimir Chutko <chutko@...> wrote:
Hi Guy,
There are too many possible causes of that "weird residue": old glass
surface, bad cleaning (both wrong materials and bad hands), bad vacuum
quality, wrong ion cleaning.... What kind of glass do you use? What is a
time gap between polishing and coating? A regular cleaning with alcohol
or acetone using special paper napkins (I can give you a brand next
week) or just washed fat free cotton ones usually provide a surface well
suitable for Al coating. Of coarse, glow discharge or ion beam
pre-cleaning in vacuum is necessary. If you use glow discharge, a
working gas actually doesn't matter, you can use even air; if you use
ion source, gases (Ar, O2, N, or their mixes) must be very pure. And
vacuum quality - oil free ultimate vacuum about 10-5 torr required.
The source(s) of those defects may be in any process step. It is hard to
discuss without detailed information about all of them....
Regards,
Vladimir Chutko
On 10/22/2010 8:09 PM, Guy Brandenburg wrote:
Question to all:
How do you perform your final mirror-drying operation before putting
that sucker into your backyard or basement vacuum chamber?
In our plain-vanilla mirror-coating operation at the NCA-CCCC
telescope-making and mirror-coating and nose-picking workshop here in
DC, which I 'inherited' from a previous leader, I think that I am
finding recently that there is some sort of weird residue on sections
of a number of newly coated mirrors - coated by us.
I suspect that it seems to come off of paper towels - at least some
brands of them, I suspect. Unfortunately, I have not done a systematic
evaluation to see if this is true, and the conditions are always just
a little bit different every time I coat or re-coat a mirror. So I am
really not sure on this at all, one way or the other. I have no idea
whether it's the final rinsing that's inadequate, or if it's something
in certain brands and varieties of paper towels themselves, or
something else. I avoid types that advertize hand-softeners or
anything like that. Sometimes I wonder whether I forgot and blew my
nose on the paper towels first. Or maybe the Green River wasn't mixed
properly. Or perhaps these mirrors just have cooties?Or perchance the
ion bombardment (aka glow discharge) wasn't long enough. Or I'm just
an idiot. Etcetera. In any case, I don't recall seeing it much before,
and it seems to be getting worse. (but even that data point is suspect.)
BTW, the setup that we have is something that was scrounged together
from 1950-to-1960-era US government surplus equipment coupled with a
variety of modifications and improvements that were crafted by my
predecessors, or donated by others. My predecessors are mostly either
deceased or are in poor health. We do this aluminization for purely
nominal fees that allow us to buy some more pitch and grit and glass.
/(The mirrors are certainly usable, but they are not elegantly clean
like I would prefer. You can see thin, dusty streaks when you look at
the mirror at certain angles. I know, I know, I should have taken a
picture. Will do so./
/
/
/(But the workshop location is clear on the other side of town. And
when I'm there, unless I go on off-hours, there are always lots of
folks building telescopes at one level or another, and they all have
questions or need advice. So I don't get to do much for myself. And
they are closed on Sundays, and normal closing time is 10 PM.)/
I have read and heard of lots of ways of doing this final drying,
including distilled water blown off by compressed nitrogen; pure
ethanol; pure this, pure that, microfibers, and more.
What methods are preferred by the present readership?
Guy Brandenburg, Washington, DC
My blog, mostly on Education in DC:
My home page on astronomy, mathematics, education:
<>
or else
=====================================
|
Re: final drying of mirror before coating
Vladimir, Neither the type of glass, nor the date of the last polishing, nor the vacuum level, nor the oil seem to me to be the source of the problem. We clean the glass, which is generally (but not always) Pyrex by first using Green River (ie HCl and CuSO4) on paper towels to remove the old coating (if there was one); then bare fingers and lukewarm water and detergent without perfumes or oils; then cotton balls and lukewarm water and detergent; then rinse with lukewarm water and cotton balls; then scrub with a slurry of powdered calcium carbonate USP and water and cotton balls; then rinse with warm water and cotton balls; and repeat all of the above until we can see, with our eyes, that there are no 'drops' of water on the surface of the glass and that the water forms a single sheet
with no imperfections. Then we dry it off with numerous paper towels. After loading the glass into the chamber, but right before we close it up, we generally spray the surface a glancing blow with some compressed air in a can, not previously shaken, and held horizontally, through a tube, supposedly to get rid of any dust particles. (It's not like we have a clean room or anything. Quite the contrary!) And we always do the ion bombardment/glow discharge for about 30 minutes with ambient air; no change there. It's easy to see the aurora vacuumalis inside the chamber. Quite pretty, especially witrh the other lights turned off. Some of the glass has been finished being figured only a day or so before being aluminized. Some, a couple of weeks. Some of it was finished figuring many years ago and then we strip off the old coating. I am more and more thinking it has something to do with the chemical composition of the towels. The ones we
are using at the moment are Safeway's home brand, and advertise that they are more absorbent than usual. (Of course, they all say that.)
I am considering using well-laundered and dried old cotton rags instead of paper towels (no fabric softener, of course), for the final cleaning. Anybody else out there use that?
?
Guy Brandenburg, Washington, DC My blog, mostly on Education in DC:
My home page on astronomy, mathematics, education: or else ?? =====================================
From: Vladimir Chutko
To: VacuumX@...
Sent: Fri, October 22, 2010 8:54:38 PM
Subject: Re: [VacuumX] final drying of mirror before coating
?
Hi Guy,
There are too many possible causes of that "weird residue": old
glass surface, bad cleaning (both wrong materials and bad hands),
bad vacuum quality, wrong ion cleaning.... What kind of glass do you
use? What is a time gap between polishing and coating? A regular?
cleaning with alcohol or acetone using special paper napkins (I can
give you a brand next week) or just washed fat free cotton ones
usually provide a surface well suitable for Al coating. Of coarse,
glow discharge or ion beam pre-cleaning in vacuum is necessary. If
you use glow discharge, a working gas actually doesn't matter, you
can use even air; if you use ion source, gases (Ar, O2, N, or their
mixes) must be very pure. And vacuum quality - oil free ultimate
vacuum about 10-5 torr required.
The source(s) of those defects may be in any process step. It is
hard to discuss without detailed information about all of them....
Regards,
Vladimir Chutko
On 10/22/2010 8:09 PM, Guy Brandenburg wrote:
Question to all:?
How do you perform your final mirror-drying operation
before putting that sucker into your backyard or basement
vacuum chamber?
In our plain-vanilla mirror-coating operation at the
NCA-CCCC telescope-making and mirror-coating and nose-picking
workshop here in DC, which I 'inherited' from a previous
leader, I think that I am finding recently that there is some
sort of weird residue on sections of a number of newly coated
mirrors - coated by us.?
I suspect that it seems to come off of paper towels - at
least some brands of them, I suspect. Unfortunately, I have
not done a systematic evaluation to see if this is true, and
the conditions are always just a little bit different every
time I coat or re-coat a mirror. So I am really not sure on
this at all, one way or the other. I have no idea whether it's
the final rinsing that's inadequate, or if it's something in
certain brands and varieties of paper towels themselves, or
something else. I avoid types that advertize hand-softeners or
anything like that. Sometimes I wonder whether I forgot and
blew my nose on the paper towels first. Or maybe the Green
River wasn't mixed properly. Or perhaps these mirrors just
have cooties?Or perchance the ion bombardment (aka glow
discharge) wasn't long enough. Or I'm just an idiot. Etcetera.
In any case, I don't recall seeing it much before, and it
seems to be getting worse. (but even that data point is
suspect.)
BTW, the setup that we have is something that was scrounged
together from 1950-to-1960-era US government surplus equipment
coupled with a variety of modifications and improvements that
were crafted by my predecessors, or donated by others. My
predecessors are mostly either deceased or are in poor health.
We do this aluminization for purely nominal fees that allow us
to buy some more pitch and grit and glass.
(The mirrors are certainly usable, but they are
not elegantly clean like I would prefer. You can see thin,
dusty streaks when you look at the mirror at certain
angles.?I know, I know, I should have taken a picture.
Will do so.
(But the workshop location is clear on the other
side of town. And when I'm there, unless I go on
off-hours, there are always lots of folks building
telescopes at one level or another, and they all have
questions or need advice. So I don't get to do much for
myself. And they are closed on Sundays, and normal closing
time is 10 PM.)
I have read and heard of lots of ways of doing this final
drying, including distilled water blown off by compressed
nitrogen; pure ethanol; pure this, pure that, microfibers, and
more. ?
What methods are preferred by the present readership?
?
Guy
Brandenburg, Washington, DC?
My
blog, mostly on Education in DC:
My
home page on astronomy, mathematics, education:
or else ??
=====================================
|
Re: final drying of mirror before coating
Yes, indeed, lots of variables. What do YOU use for the final drying, Vladimir?
? Guy Brandenburg, Washington, DC? My blog, mostly on Education in DC:
My home page on astronomy, mathematics, education: or else ?? =====================================
From: Vladimir Chutko
To: VacuumX@...
Sent: Fri, October 22, 2010 11:54:38 PM
Subject: Re: [VacuumX] final drying of mirror before coating
?
Hi Guy,
There are too many possible causes of that "weird residue": old
glass surface, bad cleaning (both wrong materials and bad hands),
bad vacuum quality, wrong ion cleaning.... What kind of glass do you
use? What is a time gap between polishing and coating? A regular?
cleaning with alcohol or acetone using special paper napkins (I can
give you a brand next week) or just washed fat free cotton ones
usually provide a surface well suitable for Al coating. Of coarse,
glow discharge or ion beam pre-cleaning in vacuum is necessary. If
you use glow discharge, a working gas actually doesn't matter, you
can use even air; if you use ion source, gases (Ar, O2, N, or their
mixes) must be very pure. And vacuum quality - oil free ultimate
vacuum about 10-5 torr required.
The source(s) of those defects may be in any process step. It is
hard to discuss without detailed information about all of them....
Regards,
Vladimir Chutko
On 10/22/2010 8:09 PM, Guy Brandenburg wrote:
Question to all:?
How do you perform your final mirror-drying operation
before putting that sucker into your backyard or basement
vacuum chamber?
In our plain-vanilla mirror-coating operation at the
NCA-CCCC telescope-making and mirror-coating and nose-picking
workshop here in DC, which I 'inherited' from a previous
leader, I think that I am finding recently that there is some
sort of weird residue on sections of a number of newly coated
mirrors - coated by us.?
I suspect that it seems to come off of paper towels - at
least some brands of them, I suspect. Unfortunately, I have
not done a systematic evaluation to see if this is true, and
the conditions are always just a little bit different every
time I coat or re-coat a mirror. So I am really not sure on
this at all, one way or the other. I have no idea whether it's
the final rinsing that's inadequate, or if it's something in
certain brands and varieties of paper towels themselves, or
something else. I avoid types that advertize hand-softeners or
anything like that. Sometimes I wonder whether I forgot and
blew my nose on the paper towels first. Or maybe the Green
River wasn't mixed properly. Or perhaps these mirrors just
have cooties?Or perchance the ion bombardment (aka glow
discharge) wasn't long enough. Or I'm just an idiot. Etcetera.
In any case, I don't recall seeing it much before, and it
seems to be getting worse. (but even that data point is
suspect.)
BTW, the setup that we have is something that was scrounged
together from 1950-to-1960-era US government surplus equipment
coupled with a variety of modifications and improvements that
were crafted by my predecessors, or donated by others. My
predecessors are mostly either deceased or are in poor health.
We do this aluminization for purely nominal fees that allow us
to buy some more pitch and grit and glass.
(The mirrors are certainly usable, but they are
not elegantly clean like I would prefer. You can see thin,
dusty streaks when you look at the mirror at certain
angles.?I know, I know, I should have taken a picture.
Will do so.
(But the workshop location is clear on the other
side of town. And when I'm there, unless I go on
off-hours, there are always lots of folks building
telescopes at one level or another, and they all have
questions or need advice. So I don't get to do much for
myself. And they are closed on Sundays, and normal closing
time is 10 PM.)
I have read and heard of lots of ways of doing this final
drying, including distilled water blown off by compressed
nitrogen; pure ethanol; pure this, pure that, microfibers, and
more. ?
What methods are preferred by the present readership?
?
Guy
Brandenburg, Washington, DC?
My
blog, mostly on Education in DC:
My
home page on astronomy, mathematics, education:
or else ??
=====================================
|
Re: final drying of mirror before coating
Hi Guy,
There are too many possible causes of that "weird residue": old
glass surface, bad cleaning (both wrong materials and bad hands),
bad vacuum quality, wrong ion cleaning.... What kind of glass do you
use? What is a time gap between polishing and coating? A regular?
cleaning with alcohol or acetone using special paper napkins (I can
give you a brand next week) or just washed fat free cotton ones
usually provide a surface well suitable for Al coating. Of coarse,
glow discharge or ion beam pre-cleaning in vacuum is necessary. If
you use glow discharge, a working gas actually doesn't matter, you
can use even air; if you use ion source, gases (Ar, O2, N, or their
mixes) must be very pure. And vacuum quality - oil free ultimate
vacuum about 10-5 torr required.
The source(s) of those defects may be in any process step. It is
hard to discuss without detailed information about all of them....
Regards,
Vladimir Chutko
On 10/22/2010 8:09 PM, Guy Brandenburg wrote:
toggle quoted message
Show quoted text
Question to all:?
How do you perform your final mirror-drying operation
before putting that sucker into your backyard or basement
vacuum chamber?
In our plain-vanilla mirror-coating operation at the
NCA-CCCC telescope-making and mirror-coating and nose-picking
workshop here in DC, which I 'inherited' from a previous
leader, I think that I am finding recently that there is some
sort of weird residue on sections of a number of newly coated
mirrors - coated by us.?
I suspect that it seems to come off of paper towels - at
least some brands of them, I suspect. Unfortunately, I have
not done a systematic evaluation to see if this is true, and
the conditions are always just a little bit different every
time I coat or re-coat a mirror. So I am really not sure on
this at all, one way or the other. I have no idea whether it's
the final rinsing that's inadequate, or if it's something in
certain brands and varieties of paper towels themselves, or
something else. I avoid types that advertize hand-softeners or
anything like that. Sometimes I wonder whether I forgot and
blew my nose on the paper towels first. Or maybe the Green
River wasn't mixed properly. Or perhaps these mirrors just
have cooties?Or perchance the ion bombardment (aka glow
discharge) wasn't long enough. Or I'm just an idiot. Etcetera.
In any case, I don't recall seeing it much before, and it
seems to be getting worse. (but even that data point is
suspect.)
BTW, the setup that we have is something that was scrounged
together from 1950-to-1960-era US government surplus equipment
coupled with a variety of modifications and improvements that
were crafted by my predecessors, or donated by others. My
predecessors are mostly either deceased or are in poor health.
We do this aluminization for purely nominal fees that allow us
to buy some more pitch and grit and glass.
(The mirrors are certainly usable, but they are
not elegantly clean like I would prefer. You can see thin,
dusty streaks when you look at the mirror at certain
angles.?I know, I know, I should have taken a picture.
Will do so.
(But the workshop location is clear on the other
side of town. And when I'm there, unless I go on
off-hours, there are always lots of folks building
telescopes at one level or another, and they all have
questions or need advice. So I don't get to do much for
myself. And they are closed on Sundays, and normal closing
time is 10 PM.)
I have read and heard of lots of ways of doing this final
drying, including distilled water blown off by compressed
nitrogen; pure ethanol; pure this, pure that, microfibers, and
more. ?
What methods are preferred by the present readership?
?
Guy
Brandenburg, Washington, DC?
My
blog, mostly on Education in DC:
My
home page on astronomy, mathematics, education:
or else ??
=====================================
|
final drying of mirror before coating
Question to all:?
How do you perform your final mirror-drying operation before putting that sucker into your backyard or basement vacuum chamber?
In our plain-vanilla mirror-coating operation at the NCA-CCCC telescope-making and mirror-coating and nose-picking workshop here in DC, which I 'inherited' from a previous leader, I think that I am finding recently that there is some sort of weird residue on sections of a number of newly coated mirrors - coated by us.?
I suspect that it seems to come off of paper towels - at least some brands of them, I suspect. Unfortunately, I have not done a systematic evaluation to see if this is true, and the conditions are always just a little bit different
every time I coat or re-coat a mirror. So I am really not sure on this at all, one way or the other. I have no idea whether it's the final rinsing that's inadequate, or if it's something in certain brands and varieties of paper towels themselves, or something else. I avoid types that advertize hand-softeners or anything like that. Sometimes I wonder whether I forgot and blew my nose on the paper towels first. Or maybe the Green River wasn't mixed properly. Or perhaps these mirrors just have cooties?Or perchance the ion bombardment (aka glow discharge) wasn't long enough. Or I'm just an idiot. Etcetera. In any case, I don't recall seeing it much before, and it seems to be getting worse. (but even that data point is suspect.)
BTW, the setup that we have is something that was scrounged together from 1950-to-1960-era US government surplus equipment coupled with a variety of modifications and improvements that were crafted by my
predecessors, or donated by others. My predecessors are mostly either deceased or are in poor health. We do this aluminization for purely nominal fees that allow us to buy some more pitch and grit and glass.
(The mirrors are certainly usable, but they are not elegantly clean like I would prefer. You can see thin, dusty streaks when you look at the mirror at certain angles.?I know, I know, I should have taken a picture. Will do so.
(But the workshop location is clear on the other side of town. And when I'm there, unless I go on off-hours, there are always lots of folks building telescopes at one level or another, and they all have questions or need advice. So I don't get to do much for myself. And
they are closed on Sundays, and normal closing time is 10 PM.)
I have read and heard of lots of ways of doing this final drying, including distilled water blown off by compressed nitrogen; pure ethanol; pure this, pure that, microfibers, and more. ?
What methods are preferred by the present readership?
? Guy Brandenburg, Washington, DC?
My blog, mostly on Education in DC:
My home page on astronomy, mathematics, education:
or else ??
=====================================
|
Re: Moderator activity...
If you have no other takers, I would be willing to assist as
a co-moderator. I am a group owner or moderator of about
20 astro-theme Yahoo groups as well as a mod on Cloudy Nights
so one more wouldn't be a problem.
I have been lurking here for a while and yet to have anything
intelligent enough to say. I am contemplating building a 1.2
meter or so chamber here in the shadow of Mauna Kea. I have
access to a number of the senior engineers of several of the
*big* professional observatories here on the island and I am
hoping that between what I learn from them and what I learn
here, I will either discover what a foolish idea this whole
project is, or at least how to do it correctly with the least
number of expensive mistakes!
"My advice is free and worth every penny!"
-Christopher Erickson
Telecom Engineer (semi-retired)
Waikoloa, HI 96738, N19¡ã57' W155¡ã47'
16" f10 Meade LX200GPS SCT
10" f3.8 Newt, Losmandy G-11 & Autostar 497
120ED f8 Orion, Vixen GP-DX & Autostar 497
5" f8 SCT Meade, iOptron Cube Pro
80ED f8 Orion, Vixen GP & Autostar 497
www.data-plumber.com
www.roboscope.net
toggle quoted message
Show quoted text
-----Original Message-----
From: VacuumX@...
[mailto:VacuumX@...] On Behalf Of Ken
Sent: Thursday, October 21, 2010 10:52 AM
To: VacuumX@...
Subject: [VacuumX] Moderator activity...
Greetings...
I have changed the availability of the Group's Archives to
allow non-members to access the past messages, perhaps this
will cause a bit more interest in the Group and lead to a
more active membership.
Also, I changed the Home Page photo and description to
reflect more recent activity on the Group.
In addition, I will be retiring from my high paid (MYTH)
Government job at the end of the month and will lose my
access to a high speed internet connection (during my
personal time) making moderation of the Group more sporatic
than it is already. I'm looking for one or a couple of
volunteer moderators to help out when I am away from the computer.
It's not really a time consuming position and is definitely
not a high profile post but it would be nice to be able to go
away for a few days and not worry about the Group.
Lastly, I still have some vacuum pumps (mechanical and
diffusion) as well as valves and other asundry goodies to
peddle since it is looking more-and-more likely that I will
not get my system together before 2012 rolls around. Anyone
need a project or some goodies?
Be well and don't forget to vote.
Ken Hunter
Owner/Moderator VacuumX Group
------------------------------------
Yahoo! Groups Links
|
Re: Moderator activity...
Aurigema, Andrew N. (KSC-ASRC-474)[ASRC AEROSPACE]
Ken,
?
Yes, they got here.? I totally forgot about them till you
mentioned them again.? I been making mirrors 100% of the time and have not
even fired up the vac chamber in months.? I am up to 18¡± mirrors
that weigh in at 8 pounds.? They still float ! ! ! !
?
I will land on my feet.? I am going commercial with the
foamglass mirrors and NASA is looking at the technology for space use.? If
you decide you don¡¯t want them quartz blanks you might want to see if
Mike Lockwood wants them.? He is in Illinois so kinda close.?
?
What is that 10¡± refractor like ????? doublet,
triplet ???
?
Drew
?
From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of Ken
Sent: Friday, October 22, 2010 2:23 PM
To: VacuumX@...
Subject: [VacuumX] Re: Moderator activity...
?
?
Thanks Drew...
I never heard if you received the rotary actuators and was able to use them or
not???
I have an 8 inch that's polished but not figured that I may send your way
sometime, possibly in the next 10 years or so. It's been in a box for at least
20 now so a few more won't make any difference. I've sold all of the old glass
except for the 2 rough quartz blanks (20 inch dia when generated).
I'm retiring finally, have been working on my shop and ham shack. Since I've
moved back to the mid-west I just can't seem to get enthusiastic about optics
and/or astronomy though I must say this October has been extremely clear for
the area.
I still have my 6 and 10 inch refractors but aleays seem to drag out the 60mm
job that is too good to throw away when I want to take a peek at Jupiter or
Saturn. Maybe I'll get busy in my retirement and build some mounts for the big
guys.
I hope that you make a smooth transition if you do get laid off, it's not a
pretty world out there these days.
Take care...
Ken
|
Re: Moderator activity...
Thanks Drew...
I never heard if you received the rotary actuators and was able to use them or not???
I have an 8 inch that's polished but not figured that I may send your way sometime, possibly in the next 10 years or so. It's been in a box for at least 20 now so a few more won't make any difference. I've sold all of the old glass except for the 2 rough quartz blanks (20 inch dia when generated).
I'm retiring finally, have been working on my shop and ham shack. Since I've moved back to the mid-west I just can't seem to get enthusiastic about optics and/or astronomy though I must say this October has been extremely clear for the area.
I still have my 6 and 10 inch refractors but aleays seem to drag out the 60mm job that is too good to throw away when I want to take a peek at Jupiter or Saturn. Maybe I'll get busy in my retirement and build some mounts for the big guys.
I hope that you make a smooth transition if you do get laid off, it's not a pretty world out there these days.
Take care...
Ken
|
Re: Moderator activity...
Aurigema, Andrew N. (KSC-ASRC-474)[ASRC AEROSPACE]
Ken,
?
Hope your leaving G-job is on your terms and not forced.? ?I too
am looking at layoff ( due to someone canceling the space program ) or I would
take the backup slot.? Any time you need to coat a mirror just send it my way
and it will get done.? You can bring it if you want to visit your old equipment
:_))))))
?
Drew in sunny FLA
------------------------------------------?
?
From:
VacuumX@... [mailto:VacuumX@...] On Behalf Of Ken
Sent: Thursday, October 21, 2010 4:52 PM
To: VacuumX@...
Subject: [VacuumX] Moderator activity...
?
?
Greetings...
I have changed the availability of the Group's Archives to allow non-members to
access the past messages, perhaps this will cause a bit more interest in the
Group and lead to a more active membership.
Also, I changed the Home Page photo and description to reflect more recent
activity on the Group.
In addition, I will be retiring from my high paid (MYTH) Government job at the
end of the month and will lose my access to a high speed internet connection (during
my personal time) making moderation of the Group more sporatic than it is
already. I'm looking for one or a couple of volunteer moderators to help out
when I am away from the computer.
It's not really a time consuming position and is definitely not a high profile
post but it would be nice to be able to go away for a few days and not worry
about the Group.
Lastly, I still have some vacuum pumps (mechanical and diffusion) as well as
valves and other asundry goodies to peddle since it is looking more-and-more
likely that I will not get my system together before 2012 rolls around. Anyone
need a project or some goodies?
Be well and don't forget to vote.
Ken Hunter
Owner/Moderator VacuumX Group
|
Greetings...
I have changed the availability of the Group's Archives to allow non-members to access the past messages, perhaps this will cause a bit more interest in the Group and lead to a more active membership.
Also, I changed the Home Page photo and description to reflect more recent activity on the Group.
In addition, I will be retiring from my high paid (MYTH) Government job at the end of the month and will lose my access to a high speed internet connection (during my personal time) making moderation of the Group more sporatic than it is already. I'm looking for one or a couple of volunteer moderators to help out when I am away from the computer.
It's not really a time consuming position and is definitely not a high profile post but it would be nice to be able to go away for a few days and not worry about the Group.
Lastly, I still have some vacuum pumps (mechanical and diffusion) as well as valves and other asundry goodies to peddle since it is looking more-and-more likely that I will not get my system together before 2012 rolls around. Anyone need a project or some goodies?
Be well and don't forget to vote.
Ken Hunter
Owner/Moderator VacuumX Group
|
Re: Coating System For Sale
Sorry I didn't see your question earlier. The coater is on eBay with no minimum and no reserve, ends 10/26 I believe. The link is in my other posting. Again, sorry I didn't see your question before!
Gordon
toggle quoted message
Show quoted text
--- In VacuumX@..., "asad" <asadscientist@...> wrote:
What is the price of the coating chamber that is for sale?
Asad
|
Re: Coating System For Sale
Hi, Everybody,
I just put my coater up for sale on eBay... No minimum bet and no reserve, so it goes in five days! Here's your chance to get the major components of a coater, probably at a low price. Link to the auction is:
Thanks!
toggle quoted message
Show quoted text
--- In VacuumX@..., "gwaitemirrors" <gordon@...> wrote:
Hi, Everybody!
I bought an old CVC coater a few years ago, intending to fix it up and start coating telescope mirrors. But I got too busy making the mirrors, so this coater project has languished. Now it's time to sell this to somebody that has the time and energy to put her back into working order.
The bell chamber is about 23.5" in diameter, and about 27.5" tall inside. I am including a rebuilt roughing pump, and a rebuilt diffusion pump, neither of which has been used since I bought them. I did run the roughing pump for a minute to make sure it would pull a vacuum. There's also a bunch of stuff like coils, aluminum pieces, SiO, diffusion pump oil, an evaporation boat, a fixture and so forth.
I have a write-up on the system, plus many, many photos on my Web site at . Click on the coater item under the "What's New" area at the top left of the page and have a look. Enjoy yourself, and feel free to make any offer on the system that would work for you. It's gotta go, so if you want a good coater project, this is a great opportunity for you. Thanks!
Gordon Waite
Waite Research
|
Ah, cool, guess I learned something today.
toggle quoted message
Show quoted text
--- In VacuumX@..., Lindsay Wilson <lindsay@...> wrote:
Hi,
Heating will do perfectly well, but the whole point of using UV lamps is
to /avoid/ heating the system. UV
of a suitable wavelength actually breaks down the water molecules and
releases them from the surface
of the chamber. Wavelengths are around 200nm. For a good overview of the
topic, check out this
page and the associated links -
Cheers,
Lindsay
No virus found in this outgoing message.
Checked by AVG - www.avg.com
Version: 9.0.856 / Virus Database: 271.1.1/3152 - Release Date: 09/22/10 07:34:00
|
INFICON instruction manuals
I am having INFICON XTM 300 for film thickness measurement. The orginal iintruction manuals has been lost. If any of our community member having these manuals, kinlfy send me the scanned copies to me.
Regards
Zafar Iqbal
|
Hi Guys,
Thank's for the answers.
Yes I was a bit uncertain. I don't want to heat up the chamber. Just want to desorb the water monolayer from the walls.
So that is why I asked the UV lamps. I found that lamp:
Osram puritec HNS. It is a low pressure lamp, with 254nm UV radiation.
It is relative cheap. I hope it wont explode under vacuum.
I would like to try the HNS L 18W, for my 20" chamber, it makes 5,5W UV radiation.
What do you think?
Attila
The Hun
toggle quoted message
Show quoted text
--- In VacuumX@..., Vladimir Chutko <chutko@...> wrote:
Hi Atilla,
Usually we use linear quartz lamps T3 series which are produced for
power from 500 to 2000 W. A lot of companies produce them; you can find
them at www.infraredheaters.com/quartz3.html, for instance. However they
are not UV lamps, they work mainly in VIS and IR range. They work fine
if you need not just "dry" your chamber and tooling, but also to heat up
substrates up to 300C - 350C maximum.
If you need just to desorb water from vacuum surfaces and leave them
relatively cold - it would be better to use UV lamps or glow discharge.
Best regards,
Vladimir
On 9/22/2010 4:45 AM, Attila wrote:
Hi All,
Does know anybody, what kind of UV lamp should use in a vacuum chamber, for heating. Eliminating the water vapour?
ThX!
Attila
The Hun
------------------------------------
Yahoo! Groups Links
|
Re: DP temperature critical?
Sometimes the DP temperature may be critical. You can not just loose the pumping speed, but also to get a strong oil backstreaming, so better to use the original heater. Usually variations about +/-10% of nominal heater power should be OK. A wide range of different heaters for many DP brands you can find at www.daltonelectric.com.
You also can control DP temperature varying the cooling water flow. Or use the VARIAC or SCR, but it is very special... nobody use them for a routine pumping...
Best regards,
Vladimir
toggle quoted message
Show quoted text
On 9/22/2010 2:45 PM, Gomez wrote: I have an old Veeco vacuum system with a≈3" diff. pump (air cooled) using 100cc of DC-704 (per factory spec).
I've torn down the entire system, cleaned it (I had to clean and rebuild the DP, as it had been dived to atmosphere hot with octoil or the like in it, and was full of tar / carbon).
The original unit should have had a 375 watt heater in it. The heater on it now is dissipating 428 watts. Interestingly, Duniway and a couple of other places sell only 350 watt heaters as direct replacements for this pump. I don't recall what temp Octoil wants, but I know that different oils require different temperatures. What I don't know is how critical that temperature is.
There is no temperature control, although I could install one at minor expense. As I understand it, too-high heat should not harm pumping action, but FAR too much heat will cause erratic pressure variations as excess condensation interferes with the jets.
So, how important is precise temperature control of the boiler? Should I pick up a temperature controller (using the present too-high wattage heater and a thermocouple) or should I replace the heater with a 375 watt unit, or a 350 watt unit, or should I just not worry about it?
------------------------------------
Yahoo! Groups Links
|
Christopher Erickson