Cletus
22-Nov-2013, 15:10
Ok, this is probably a question for Sandy King, or on the other hand, it might be a completely "over-nuked" and altogether irrelevant issue in the first place, so here goes -
I'm looking to replace the glass in my B&S contact printing frame with something a little thicker and more durable than what's already in there, which I mildly suspect is ordinary, garden variety soda lime float glass, i.e., cheap window glass.
My first thought was to get a piece of tempered glass from an architectural supply house, but that turns out to be unrealistic from a cost standpoint and for other reasons. High quality picture frame glass was my next guess, but therein lies the problem. Good picture frame glass tends (I assume) to have coatings or other properties that are designed to block UV light, rather than efficiently transmit it, which is counter to my intent.
So, my question is: Has anyone ever experienced problems finding suitable contact printing glass for Pt/Pd and other UV dependent alt process applications? Or, has anyone ever actually used a piece of glass in a contact printer that happened to have some anti-UV coating or characteristic and caused problems with printing?
My "research" turns up that borosilicate glass would be a good choice in that it is durable, resistant to chemicals and scratches and it also transmits light well, including UV-A in wavelengths from about 350nm and up at around 90%, which is good. I guess. Since 400-500nm, or UV-A to near visible seems to be within the range required to "expose" ferric oxalate sensitizer.
The bottom line is, I'm looking for a piece of glass that's a little thicker and more durable than what I'm using now and which has nice smooth finished edges for easier, constant handling. I have a quote for a sheet of 3mm AR coated "Water White" glass and 3mm uncoated borosilicate glass, either of which should work fine. I'm just wondering whether anyone has ever looked at, or even considered UV transmission properties of glass for contact printing with UV processes. Maybe all this concern with UV light transmission is totally negligible and I should just use whatever glass I can get my hands on?
I'm looking to replace the glass in my B&S contact printing frame with something a little thicker and more durable than what's already in there, which I mildly suspect is ordinary, garden variety soda lime float glass, i.e., cheap window glass.
My first thought was to get a piece of tempered glass from an architectural supply house, but that turns out to be unrealistic from a cost standpoint and for other reasons. High quality picture frame glass was my next guess, but therein lies the problem. Good picture frame glass tends (I assume) to have coatings or other properties that are designed to block UV light, rather than efficiently transmit it, which is counter to my intent.
So, my question is: Has anyone ever experienced problems finding suitable contact printing glass for Pt/Pd and other UV dependent alt process applications? Or, has anyone ever actually used a piece of glass in a contact printer that happened to have some anti-UV coating or characteristic and caused problems with printing?
My "research" turns up that borosilicate glass would be a good choice in that it is durable, resistant to chemicals and scratches and it also transmits light well, including UV-A in wavelengths from about 350nm and up at around 90%, which is good. I guess. Since 400-500nm, or UV-A to near visible seems to be within the range required to "expose" ferric oxalate sensitizer.
The bottom line is, I'm looking for a piece of glass that's a little thicker and more durable than what I'm using now and which has nice smooth finished edges for easier, constant handling. I have a quote for a sheet of 3mm AR coated "Water White" glass and 3mm uncoated borosilicate glass, either of which should work fine. I'm just wondering whether anyone has ever looked at, or even considered UV transmission properties of glass for contact printing with UV processes. Maybe all this concern with UV light transmission is totally negligible and I should just use whatever glass I can get my hands on?