Re: Chrysotypes and humidity

[Lukas Werth <lukas.werth@rz.hu-berlin.de>]

At 11:45 14.08.01 +0200, you wrote:
>Last weekedn I gave chrysotype printing a try, using the protocol of
>Tony McLean had genereously send to this list in 1999.
>
>Ther first attempts worked quite nice, the only problem beeing the
>humidity. It seems that Chrysotypes are very sensitive to humidity (just
>as Ziatypes), and it happens thta the colour scheme which intersts me
>most: maroon/purple/blue only "happens" when the humidity is around 50%,
>not around 95% as it is currently in Holland... When drying with forced
>air I could shift the colour schem a bit from black/grey/bleu towards
>violet/blue., but I am not there yet.
>
>Do people have experience with humidity chambers? I know that a chamber
>with beaker of stuarated CaCl2 should have a humidity of around 35% or
>so.
>
>I am wondering: how long would it take for a coated Chrysotype to reach
>this rel. hum. from say 80 to 35%?
>
>Would it help to have the paper before coating as dry as possible? (even
>heat it?)
>
>Cor
>


Cor,

I have cat litter trays with saturated solutions in them for humidity
control. Ammonium chloride for 85%, calcium nitrate for 65%, calcium
chloride in powder form ca. 10%, in sat. sol. ca. 40-50%(?), all ideally 20
C, which means for me room temperature. The paper is taped on the lid (a
laminated fiber sheet). I usually dry the paper first over calcium chloride
powder, and then bring it to the desired humidity over the other solution
(over each between 1/2 h and 1 h).

Lukas