RE: printing gum on glass
Chris
Good to hear the list is alive. I will miss the APIS activities this year. I really wanted to go this year, but something came up last moment. As far as the gum on glass I have tried it last summer. I made a couple of very thin blue layers for the preparation for tricolour gums. With very thin layers my exposures were short, and I remember long development times as well. I do not think I optimised it. The project was never finished as one day my stack of plates crashed and I never started again. I was very tempted to do some gum on glass with the back exposure. This should give a nice continuous gum layer sticking to the glass. If you have a colimated UV light source that would be the ideal way to make gum on glass. Direct sun exposure is another possibility, which I might try this weekend. What is the typical direct sun exposure (not in the shadow) if anybody is using this method. A good guess would save some calibration tests.
Marek Matusz
From: "Christina Z. Anderson" <zphoto@montana.net>
Reply-To: alt-photo-process-l@usask.ca
To: "Alt, List" <alt-photo-process-L@usask.ca>
Subject: printing gum on glass
Date: Sat, 14 Jul 2007 09:23:40 -0600
>Quiet list this summer! Is no one doing photography???
>
>Tomorrow on my 4th of 6 trips this summer (gasp); onto APIS. No
>rest for
>the weary. Hope to see some of you there. In between trips I work
>on myth
>busting.
>
>Anyone print gum on glass? I was working on an example to disprove
>the myth
>that printing on glass produces no midtones, a myth that seems to be
>repeated in books and is based on the assumption that the surface is
>sooo
>smooth with no bumps that it will not hold the midtones.
>
>Well the total image printed as I suspected. But I noticed an odd
>thing--the top layer of gum when it hit the water sloughed off in
>pieces,
>revealing the complete image below it. I wanted to see if anyone
>else had
>noticed this or even printed an image on glass (probably not), and
>if, those
>of you carbon printers (Sandy?) have said unequivocally that your
>tissue
>hardens from top down, correct?
>
>This example is not refuting that theory--because the top slough off
>layer
>was hardened. But I still am working on the solarplate statement,
>perhaps
>ultimately not at all related, that solarplate hardens from the
>bottom up
>and why that might be
different than gum. I do not know what the
>photosensitive substance is in solarplate but the polymer being
>hardened is
>either nylon or pva and perhaps other things, and pva is also used
>in
>dichromate processes.
>Chris
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>_____________________________________
>
>Christina Z. Anderson
>Assistant Professor, Photo Option Coordinator
>Montana State University, VCB 220
>Box 173350
>Bozeman Montana 59718
>406.994.6219
>CZAphotography.com
>_____________________________________
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