[alt-photo] Re: further cyanotype observations

[Christina Anderson]

Loris and Henry,

I use 20% A to 8% B 1:1, which if I do the calculations of Alberto's mix/your mix, Loris, I should be at 20%A to 9.6% B so I could up the B a bit.

I got tremendous bleeding with 2A:1B and that was when the conversation started a couple years back and Alberto was such a saint to explain it to me why.

When I went back to this testing spate to 1A:1B I was expecting quite a bit longer exposure times for all my papers (a stop I figured) but that is what surprised me so much--that my exposure time on even FAEW is 8 minutes!! In fact, with a 30% humidity, my exposure times range from 2.5-10 minutes on all papers.

My surmise is that humidity is a great factor.

I have not used Tween in any of these tests, preferring to start from square one.

The only question I have remaining is this: is it possible that an old solution of cyanotype A and B increases in speed over time. My solutions are about a year old, not freshly mixed. Stored in light tight bottles in cool, dry temps.

But "as for me and my house" I will turn on the humidifier in my dimroom always. Even in summer humidity here is severely low.

Chris


Christina Z. Anderson
christinaZanderson.com

On Feb 28, 2012, at 8:12 AM, Henry Rattle wrote:

> Loris - does A:25%, B:12% mean you take a solution of 2A:1B and then dilute
> further with about 2 volumes of water?
> 
> 
> 
> 
> On 28/02/2012 14:44, "Loris Medici" <mail at loris.medici.name> wrote:
> 
>> Dear Christina,
> 
> Could be by both... (BTW, I now exclusively use Alberto's
>> A:25%,
> B:12%.) I was using Ilfotol (a wetting agent) with some papers - when
> I
>> first started. (You use Tween there...) I guess it's a matter of
> finding the
>> optimum balance between the coating volume, wetting agent
> and application
>> method. (BTW, Masa usually takes less emulsion than
> other thicker papers;
>> something like 0.2ml per 10 sq. in. But that
> depends on the size of the print
>> too; I noticed that larger prints
> require slightly more emulsion - maybe
>> because using larger brushes
> and longer application
>> times...)
> 
> Regards,
> Loris.
> 
> 
> 28 Şubat 2012 16:18 tarihinde Christina Anderson
>> <zphoto at montana.net> yazdı:
>> Dear Loris,
>> From something Alberto said a
>> while ago, I wonder if the bleed is due to the ratio
>> of A to B also. But I
>> have seen bleed in both pt/pd and cyanotype when the
>> solution sits on the
>> paper and does not
>> absorb.
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