On 02/21/2015 05:37 PM, Thomas Janstrom t_janstrom@... [VacuumX]
wrote:
Guy,
Are you sure the marker tip didn't in fact "polish" a groove into the
surface? Some of the felt tip markers use fibre glass for the tip so it
might be more abrasive than you expect. Just a thought.
Thomas.
I wonder if the type of glass might be a factor?
--
Kirk Wallace
Kirk Wallace