[alt-photo] Re: coffee and cyanotype

[Loris Medici]

Francesco, I would agree that it highly depends on perception / goals.
In any case, for sake of being clear: The veiling / warming I
experienced was only noticeable when comparing treated vs. non-treated
paper.

In case you may want to try it again, let me describe my stragety,
maybe you'll find it useful somehow:
* Slightly underexpose (in contrary of the common advice to overexposing...)
* Wash / clear well before bleaching/toning (tannic acid will tone
not-well-cleared specular highlights...)
* Use papers well / hard sized papers with a tight structure / surface
* Little bleach (for more controlled bleaching, especially when you
want to split-tone) and little tannic acid is more than enough. (What
you get is not what you see in the toning bath; there's consiredable
coloration / dry down / darkening / curing while the print dries...)

Regards,
Loris.


2012/1/13 Francesco Fragomeni <fdfragomeni at gmail.com>:
> 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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