RE: Gums a la Demachy and Puyo and all sorts of other things including cyanot...

Are you kidding?
 
Classic Cyanotype:
 
Two solution sensitizer (you mix equal parts just before coating - that's an
extra step compared to new cyanotype).
 
Solution A is Ammonium Iron(III) Citrate (an ill defined compound; for
instance, I never managed to mix Vandyke or Argyrotype without precipitation
with mine - B&S stuff - but Mike W. says he doesn't get precipitation with
his stock from another supplier), optionally one can add small amnt. of
Sodium Benzoate, Formaldehyde ect. for mold/fungus growth prevention (not an
issue with new cyanotype)
 
Solution B is Potassium Ferricyanide.
 
Making stock solutions consist of weighting necessary amnt. of compounds and
mixing them with water (two separate solutions). 5 minutes... BTW, weighting
Ammonium Iron(III) Citrate is harder compared to Ammonium Iron(III) Oxalate
because is very hygroscopic, tends to stick everywhere especially when RH is
high, also you have to weigth in bigger containers since its volume per
weight is high / it gets airborne quite easily. Weighting Ammonium Iron(III)
Oxalate is very easy, it's in crystal form (doesn't stick to the container's
sides / plastic spoon ect) and it's quite heavy (doesn't get airborne).
 
 
New Cyanotype:
 
One solution sensitizer. Making stock solution consist of weigthing
necessary amnt. of compounds, heating water to 70C, mixing the compounds
with water (two separate solutions), mixing the solutions. This takes 10
minutes... Then you wait around 1h to let the solution cool, you filter the
solution (slowly pouring to a new container also works since the precipitate
is quite heavy), add water to make up the final volume and voila (an extra 5
mins lets say)...

There's not much difference apart the 1h waiting time. Procedure with
classic formula takes 5 minutes, procedure with new cyanotype is 15 minutes
(I don't count the 1h wait because usually one does other things instead of
watching the solution while it cools). The 10 minutes difference will even
out later when you make prints - because you don't have to mix two solutions
before every coating operation with new cyanotype, you also don't have to
occasionally filter the mold if you don't use any preservative for classic
formula solution A)...
 
Compounds used are Ammnium Iron(III) Oxalate and Potassium Ferricyanide.
(Optionally one can add small amnt. of Ammonium Dichromate for long-term
preservation and contrast control)
 
 The remaining steps are the same for both processes: Coat, dry, expose,
wash in water, clear (in citric acid - if the paper needs it, that is),
optional peroxide bath (for seeing dark blues earlier) and dry.
 
So?

Loris.

________________________________

From: TERRYAKING@aol.com [mailto:TERRYAKING@aol.com]
Sent: 19 Temmuz 2006 Çarşamba 00:52
To: alt-photo-process-l@usask.ca
Subject: Re: Gums a la Demachy and Puyo and all sorts of other things
including cyanot...

Given your experience, it would be helpful if you could set out the method
and the chemistry of the 'new cyanotype' and the 'classic' method, side by
side so that we can make a comparison.
Received on 07/19/06-01:13:03 AM Z