Cyanotype & VDB/ was Van Dyke Help Sought

SCHRAMMR@WLSVAX.WVNET.EDU
Sun, 15 Sep 1996 19:12:12 -0400 (EDT)

Judy,
Sorry I do not remember where I read that about keeping in seperate
bottles but I did accuratly copy the formulas and the sensitizer is
mixed in three parts. The sentence, "Combine parts A,B and C just before use"
is appended to the formula. Why that statement? What not combine A, B and
C at the beginning? I am not questioning your observations which I believe,
just letting you know where I got the idea.
I have kept my cyanotype formula in two seperate bottles for at least
six (6) months and have not noticed any deterioration of the image, but as
you say, the change may be subtle. Nevertheless, I hate to give up my
oxalic acid as I really believe I get better clearing in the highlights.
I am going to try the tartaric acid VDB formula however.
Last night I mixed some cyano sensitizer from my two bottles which
were about a month old at this point and made three prints. I coated some
extra sheets of paper (Strathmore 100% rag- no size) dried them and put
them in a light tight box. Today, about 12 hours later, I got the sheets
out to try and make some more prints, same neg, same exposure. I noticed
that the nice even yellow-green color had turned light prussian blue.
Made a print anyway. Result: very little contrast, muddy, can not get the
highlights to clear.
This could indicate two things. First, the oxalic acid is doing something.
I believe oxalic acid is pretty reactive. Second, the twelve hour interval
allowed the cyanotype sensitizer to get itself very firmly attached to the
paper fibers and a lot of washing may be necessary. For the record, the
wash was 10 min. I have tested my wash water it is slightly acidic. I mix
all sensitizer solutions with distilled water.
When I get time I'm going to do a more thorough comparison test of
the two formulas for cyano and VDB.
Finally, I saved some of the mixed cyano sensitizer in a small brown
bottle which I put away in a dark, cool cupboard. I will get it out in
a few months (Xmas vacation) and try it out.

Just kidding about the NY water. Actually, you tap water may be better
than ours. Ours comes from the Ohio river. All the local land fills drain
into creeks which drain into the river. Also there is all kinds of
opportunities for manufacturers from Wheeling to Pittsburgh and south
to Morgantown along the Monongehala river to have "accidental" spills.
We have an activated charcoal filter on the drinking/cooking water tap.
Some mornings the shower water smells odd.(there are all kinds of...)

Bob Schramm