[alt-photo] Re: coffee and cyanotype

[Francesco Fragomeni]

Loris,

This is probably a matter of perception here. A slight staining of the
paper base is generally expected with tea toning and tannic acid toning and
many people look for it as an effect of the toning process. For my
particular purposes I was working on a way to get the toning without any
staining to the paper base so my perception is most definitely skewed. Any
stain beyond only the most imperceptible hue is significant to me. If I can
visually see a lowering of my highlight values I'm unhappy and measurements
confirm (using densitometer) that even a slight stain accounts for
substantial density in the paper base which for me is something that is
visually unappealing (again for my purposes, I like it a lot in other
people's work). Sorry, didn't mean to be confusing or inaccurate in my
language. You're correct that there are ways to minimize the stain but even
in those cases the stain is too much for me or it doesn't yield enough
toning effect.

-Francesco


On Fri, Jan 13, 2012 at 7:30 AM, Loris Medici <mail at loris.medici.name>wrote:

> Francesco, the "bringing down the paper base significantly" issue doesn't
> reflect my past experience with tannic acid at all. Yes, there would be a
> slight veiling or warming (when compared to unprocessed paper, *side by
> side*) of the paper base, but to me it' was far from being significant. My
> workflow was: expose, wash / rinse (a couple of changes), clear in mild
> citric acid (1-2%), wash / rinse again, bleach in mild sodium carbonate (a
> dessert spoon into 2000ml), tone for 3-5 minutes in weak tannic acid (a
> dessert spoon into 2000ml), wash / rinse again. Depends on the sizing
> strenght of the paper; hard sized papers such as COT 320 are quite
> resistant
> to staining by tannic acid.
>
> Regards,
> Loris.
>
>
> -----Original Message-----
> From: alt-photo-process-list-bounces at lists.altphotolist.org
> [mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf
> Of
> Francesco Fragomeni
> Sent: 13 Ocak 2012 Cuma 16:18
> To: The alternative photographic processes mailing list
> Subject: [alt-photo] Re: coffee and cyanotype
>
> Toning in coffee is indeed different then tea toning or pure tannic acid
> toning. There are a number of different components in coffee which act
> differently on the paper and iron in a cyanotype. Depending on the coffee
> and duration of toning time, coffee toning can actually yield a more grey
> to
> black tonality with less stain to the paper base then can be achieved with
> tea toning and tannic acid which are notorious for bringing down the paper
> base significantly.
>
> -Francesco
>
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