I prepared the sensitizer as indicated in the article including grinding
with morter and pestle, using heated distilled water, filtering, etc.
Everything went as stated in the article.
Initially I used Strathmore paper. This resulted in a number of funny little
spots which appeared unpredictably in the prints. I then switched to my
favorite cyanotype paper, Rives BFK. I can't say that the spots all disappeared.Every third print a funny little dark spot would appear somewhere.
All coating was done with a new foam brush.
The first observation was that this process is much faster, as was stated
in the article. A negative that took 10-12 minutes to print with the old
process took 2-3 minutes with the new process using my light source.
I made prints with the same negative using my old formula and the new
formula. The article states that there is an increase in Dmax. I did not
observe this. With my old formula the whites clear nicely with just
water. I found I had to soak prints made with the new formula in hypo
clearing agent to get them to clear. This caused some fading of the image.
I did discover that prints made with the new formula responded well to
both lead toning and Seigel toning. Of course my old formula does this
also.
In preparing the sensitizers I notice both my old formula and the new
formula contain ammonium dichromate in about the same amount. My old
formula contains oxalic acid. The article suggests that citric acid
could be added to the new formula to help in clearing. I didn't have any
so I could not try that. Perhaps that explains why I had trouble clearing
prints made using the new formula.
In summary, the only advantage I can see to using this new sensitizer
is speed. It has been mentioned that the new process results in prints
that are more stable. I did no tests on this. In my opinion, there are a
number of disadvantages. This new formula is more toxic. Mixing the
sensitizer is more time consuming. I had some clearing problems and
still have not determined what caused the mysterious dark spots to
randomly appear only in the new process prints.
I am not finished with this. The article states that the sensitizer works
better after it ages a few days. So right now we are doing that (ageing).
Bob Schramm