RE: cyanotype on glass ( how to clean the glass and other stuff)

Carmen,

I'm a wet-plate artist who primarily makes ambrotypes (positive images on
glass). Becoming an expert glass cutter and preparer was a good part of my
training: I think you will find the preparation process we use a good
cognate for your student:

Preparing the Glass:

Supplies:
* Rotten stone cleaner (equal parts rottenstone, denatured alcohol and
distilled water) mixed in a mustard/catsup flexible bottle with squirt top.
I buy the clear ones from my local drug store in the beauty section since
the ingredients will separate after a few minutes and you can easily see
this when the bottle is clear, thereby knowing when to shake it up.
Rottenstone is a pumice-like substance (black) with few equals for glass
cleaning. Many places sell it online, but I find it here in San Francisco at
both specialty paint and woodworking stores--better to call around a bit.
* Soft cotton cloths (I use 100% cotton t-shirts) LINT-FREE
* Arkansas stone (a white-colored whet stone from Arkansas found at hunting
supply stores--much harder to find in San Francisco :-) Black whet stones
will work, but are much rougher then the glass needs so try to find the
Arkansas stone ($3-5 bucks)
* Sable or camel hair brush

1. Lightly run the Arkansas stone along ALL edges of the glass abrading them
slightly. For a square or rectangle piece of glass this would be 12
locations. Top edges, bottom edges, and then directly along the outer
edges-perpendicular. Do you follow? The does two things: 1. Provides a tooth
for the edge of your coating material to adhere to and 2. softens the edges
of the glass so it doesn't cut you.
2. Squirt a quarter to half-dollar size amount of rottenstone cleaner on one
side of the glass. The color will be a dark-gray and you'll wonder how this
can really clean glass, but continue... BTW, you can't use too much so just
squirt enough on to cover your plate when rubbed in.
3. Use three dry cloths in succession. The first to rub the rottenstone
cleaner onto the glass like polish to a car--be aggressive. The second to
remove much of the dried cleaner. The third to buff the glass thereby
removing any remaining cleaner. To verify that the glass is clean, you can
breathe on the surface of the glass and examine the fogged glass for any
streaks or imperfections. Any grit, no matter how small, must be removed or
it will likely cause your coating material to wash off or mare your final
image. This may be less crucial for your student's purpose, but a single
spot on an 8X10 plate for an ambrotype will cause the image to slide off the
plate during the wash.
4. Allow the glass plate to "gas-off" for 2-3 minutes
4. Gently brush any remaining lint, dust, etc from the glass with your
sable/camel hair brush before coating.

Let me know if you have any additional questions or comments.

Mark

-----Original Message-----
From: Carmen Lizardo [mailto:carmenlizardo@yahoo.com]
Sent: Wednesday, January 26, 2005 11:07 AM
To: alt-photo-process-l@sask.usask.ca
Subject: cyanotype on glass ( how to clean the glass and other stuff)

Dear list,
A student of mine (Kelly) wants to do cyanotype on
glass. She has been fallowing Galina's technique
published in the Christopher James book, but we cant
figure out with what to clean the glass. I found that
the C. James book recommends something called
"rottenstone" but I dont know what this is or where
to get it.
And a couple of more questions: The formula for the
sensitizer calls for one part "prepared" gelatin to
two parts sensitizer, is this prepared solution a
combined mix of gelatin and hardener such as glyoxal?

What is the easiest way to coat the glass?

Thank you kindly

Carmen and Kelly

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Received on Wed Jan 26 16:26:52 2005