U of S | Mailing List Archive | alt-photo-process-l | RE: Gum over Cyanotypes

RE: Gum over Cyanotypes

Judy and all,

After making my reply last night I began thinking about the reasons why I
pre-shrink twice. 

I had forgotten that sheets float to the top of the water. Even a large
stack will bob on the surface. This causes the topmost sheet to dry out. So
as a precaution (even though I rotate the sheets - top sheet to the bottom
of the stack) I pre-shrink twice. 

Handling large sheets when wet and soggy is a chore but when all of the work
is done I can chop/trim the sheets to needed size after sizing. In the end I
find shrinking and sizing whole parent sheets much more time efficient.

As for the sizing step I have a large table setup with a big piece of white
plexi that I tape the parent sheets to using 3m low tack removable
transparency tape. To the side I have an electric griddle setup to heat a
liter of gelatin with hardener. I withdraw the gelatin with a BIG syringe,
sucking up 36-37 mls of hot gelatin for each sheet.

The gelatin is squirted from the syringe onto the paper in a back and forth
up and down motion. I then brush out the gelatin with a foam brush left to
right - top to bottom with horizontal strokes. I do this quickly. I then
repeat the brushing action using vertical strokes which I also do quickly. I
have a light positioned to the side of the paper to illuminate the paper in
a manner that allows me to see the wet gelatin on the paper to ensure no
sections are missed. My gelatin coats are very smooth and even though
possibly thicker than what others place on their papers.

I allow the gelatin to set for a couple of minutes and then hang the sheet
to dry. The tape pops off the corners easily and is tossed into the trash.
Of course I work with gloved hands and goggles.

After I've filled all of my drying lines I leave the sheets to dry to the
touch. Just before leaving I wicked any drops of gelating from the bottom
corners. Two clothes pins hold each sheet up on the line. The floor beneath
the sheets is covered with paper to catch any drips. 

The gelatin is left on the griddle with a glass cover plate to coat the next
batch if there is one. Otherwise the gelatin gets poured into the trash and
the pyrex beaker is moved to my darkroom for cleaning. Leaving the gelatin
to cool and dry makes cleanup really a chore so I deal with that right away.

For the record I follow the same procedure for Fabriano EW or Traditional
White and Rives BFK which is my favorite gum paper.

Don Bryant