From: Sarah Van Keuren (svk@steuber.com)
Date: 04/30/00-08:09:29 AM Z
>
>
>> A simple toning process that I have used and taught
>> for years consists of
>> bleaching a cyanotype in dilute household bleach
>> (NaOCl) and bringing back
>> whatever got bleached away in tannic acid.
>>
>>......
>>
>> Sarah Van Keuren
>
> The instructions I followed called for Amonia. Has
> anyone done a side-by-side comparison? Bleach/Amonia
> then to Tannic Acid. I guess both are a base are they
> not. Its been 5 years since I had a Chemistry course.
>
> Thanks.
>
> Jonathan Long
> jon@jonlong.com
>
Yes, I have used ammonia too. Its bleaching effect on the cyanotype seems
less definite, more mutable in the shifting of hues. I settled on bleach for
that reason and because it may be slightly less noxious in terms of fumes
than bleach but I have not done a side-by-side comparison of results.
Ammonia may be less destructive of the paper fiber and easier on the
environment. I don't particularly emphasize this way of working because of
these issues and aesthetic reservations. I'd rather print in gum if I'm not
doing a blue cyanotype.
Sarah Van Keuren
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