[Alt-photo] tannic acid
ravene at gmail.com
Thu Jun 15 05:32:43 UTC 2017
Different bleaches do change the tone!
If you use baking powder to bleach then green tea you get a rather nice
I found that tannic acid didn't work as well as green tea for me. And
coffee stained the paper more than toning the image.
On Wed, Jun 14, 2017 at 10:22 AM, Bob Cornelis via Alt-photo-process-list <
alt-photo-process-list at lists.altphotolist.org> wrote:
> Thanks Christina
> I am embarking on a "survey" of toning techniques, many of them from your
> book! I've done lots of tea toning in the past - I'm not a big fan because
> of the heavy staining in the highlights. Recently I've had better success
> in that regard with coffee toning. I'm curious if straight tannic acid
> gives me more control than tea bags and perhaps less staining.
> I've got some other chemistry on its way, like glacial acetic acid and
> playing with different bleaches as well.
> It's not clear to me in my reading whether different bleaching solutions
> give different tones or results at the end of the process, or whether they
> all basically do the same thing.
> On Wed, Jun 14, 2017 at 9:20 AM, Christina Z. Anderson via
> Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org>
> > Bob,
> > You do not need purified tannic acid to tone cyanotypes. You can tone
> > cyanotypes with brewed strong tea as well, e.g. 5 teabags to a couple
> > of water. You can use green tea. You can use walnut husks. etc. etc. and
> > the list goes on. Anything with tannic and gallic acid.
> > I have used both the scientific grade tannic (and gallic), which actually
> > smells like tea (a very fine powder) and regular tea as have all my
> > students for over a decade.
> > It doesn’t get used up very fast so if you were to buy scientific grade,
> > get a small amount.
> > Chris
> > > On Jun 14, 2017, at 9:48 AM, Bob Cornelis via Alt-photo-process-list <
> > alt-photo-process-list at lists.altphotolist.org> wrote:
> > >
> > > I'm looking for a good, inexpensive source for tannic acid to do
> > cyanotype
> > > toning. Does it matter greatly whether I buy this from a
> > > chemical/photography supply company or some place like the following:
> > >
> > > http://www.dharmatrading.com/chemicals/tannic-acid.html
> > >
> > > Much cheaper, but I'm not sure what kind of purity/control I really
> > > for this. Any experience or suggestions?
> > >
> > > I can get 100gms at Photographers Formulary for about $29, but am
> > > for something in greater bulk and cheaper.
> > >
> > > Thanks!
> > > Bob
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