Re: Cyanotype II & Citric Acid

Hi Michael,

Soaking for 10 minutes in a 1-2% citric acid bath after exposure will
strengthen shadow values and extend the contrast range slightly
(approximately 1/2 stop). There are some indications, via Dr. Ware, that a
citric acid bath will cause fading and he now recommends using a 1%
hydrochloric or nitric acid bath instead.

As a side note, a solution of 40% citric acid (40gm in 100ml) can be added
directly to the sensitizer at ther rate of 1-5 drop(s) per ml of solution
for increased tonal (contrast) range of up to 2 stops. If you experience
problems with the sensitizer reacting adversely to a certain paper, adding
citric acid directly to the sensitizer before coating will help. I have
found that just 1 drop of 40% citric acid per ml of sensitizer allowed me to
print on papers where the sensitizer turned blue within 5 minutes of coating
(before drying).

Hope this helps, Scott

----- Original Message -----
From: "Michael Koch-Schulte" <mkochsch@shaw.ca>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Tuesday, March 08, 2005 1:57 PM
Subject: Cyanotype II & Citric Acid

> I'm using citric acid as my clearning agent for Cyano version II. In broad
> general terms what changes should I be seeing if I'm adding too much or
too
> little just before coating? More contrast? Loss of contrast? Fogging? etc.
> Currently, I'm adding .25ml for every 2 ml of sensitizer.
>
>
Received on Tue Mar 8 16:16:16 2005