Loris,
Well here is my
method for pre-shrinking FAEW or FAT.
First I pre-shrink
parent sized sheets 10 at a time in our garden sized bath tube for several
hours with luke warm water. Initially each sheet is immersed and allowed to
become saturated with water. After all of the 10 sheets are in the tube I will
inter-leave the sheets slowly over a period of several hours. I handle the
sheets with care to prevent scuffing of the paper surface. After 5 or 6 hours
(by that time the water is cold). I’ll pull the sheets and hang to dry
completely. After the sheets are dry I will repeat the process. Over a period
of days I will pre-shrink a batch of 100 sheets.
After the second
pre-shrink cycle I size the sheets with gelatin hardened with glutaraldehyde.
Those are hung to dry and after drying are stacked carefully in one of the
drawers of my flat file cabinet. The stack is weighted to help flatten the
stack.
I print cyanotype on
the sized paper and never have a problem doing so. Printing the cyanotype on
the sized paper makes for a sharper image, IMO. I register negatives by eye
for gum exposures by laying the coated sheet on a light box with a sheet of
glass lying on top of the negative. The negative is taped in place once the
registration is achieved and then exposed to UV. I never have any problem
registering negs 11x14 or smaller.
For gum over
palladium I acidify the paper in Oxalic acid (5% for 20 minutes) though I
don’t do this with parent sized sheets. I’ve never had a problem with the so
called calcium carbonate deposits coating the paper surface after the oxaclic
acid bath. I also have concerns about using an inorganic acid such as HCL
affecting the archival qualities of the paper, even a dilute solution.
After the palladium
layer has been printed then I size the paper with gelatin hardened with glut.
I have done as many as 5 to 6 gum layers, though typically it’s 3 or 4 gum
layers with different dichromate dilutions with different pigment colors. I’m
not much into gum over cyanotype unless I do tri-color. I never have a problem
with staining, my prints look sharp.
So, there is more
than one way to skin the gum cat. I am concerned about the pH of the paper
after clearing in sodium metaborate as a result I wash the prints well. I have
a high chlorine content to my tap water so I’m sure my prints aren’t pH
neutral after the wash. But I soilder on never the less.
Don
Bryant