[pure-silver] Re: Thiourea and Thiourea dioxide
- From: Ray Rogers <earthsoda@xxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Wed, 23 Feb 2011 09:50:52 -0800 (PST)
Correct... not all sites show a difference.
I think the FSA or thiourea dioxide toner is more for a special effect. Since
you read about it in Tim's book, did you get the result you were after, even
though it was slow in working?
I suspect you didn't, in which case you might need to spring for it, if that is
really a look you are after....
Ray
--- On Wed, 2/23/11, Eric Nelson <emanmb@xxxxxxxxx> wrote:
From: Eric Nelson <emanmb@xxxxxxxxx>
Subject: [pure-silver] Re: Thiourea and Thiourea dioxide
To: pure-silver@xxxxxxxxxxxxx
Date: Wednesday, February 23, 2011, 3:57 PM
I looked it up myself and found these for t. dioxide with the 2 different CAS
#'s:
http://www.lookchem.com/cas-418/4189-44-0.html
http://www.thiourea-dioxide-fas.com/ <--CAS# 1758-73-2
This is what I found for my thiourea:
http://www.jtbaker.com/msds/englishhtml/t3107.htm
I won't pretend I know anything about what's on those pages as I'm just looking
for the practical application of the compound with this toner.
I used my thiourea anyway as I was in a testing mode yesterday and did get
toning, albeit very slowly, of the prints I had bleached with the
ferricyanide/pot. bromide combo. That may be my "practical" answer right
there, but since I work w/chemicals w/o getting into molecular structures and
formulas, I'm hoping someone who does might know the answer if it's 'worth'
looking into getting the t. dioxide or not.
Eric
From: Ray Rogers <earthsoda@xxxxxxxxx>
To: pure-silver@xxxxxxxxxxxxx
Sent: Wed, February 23, 2011 4:45:55 AM
Subject: [pure-silver] Re: Thiourea and Thiourea dioxide
Sources I looked at gave different yet presumably equvilant structures for
those two cas #s
Thiourea is different.
???
Thiourea sulfoxide?
Did you mean thiourea dioxide rather than sulfoxide?
(Can you supply the CAS # for that?)
Ray
--- On Wed, 2/23/11, daniel <daniel.bouzard@xxxxxxxxxx> wrote:
From: daniel <daniel.bouzard@xxxxxxxxxx>
Subject: [pure-silver] Re: Thiourea and Thiourea dioxide
To: pure-silver@xxxxxxxxxxxxx
Date: Wednesday, February 23, 2011, 7:01 AM
Hello,
CAS 4189-44-0 and 1758-73-2 are both for thiourea dioxide under different
names. CAS 62-56-6 is for thiourea.
Several years ago I tried toning with thiourea sulfoxide following Tim book and
it worked very well.
Daniel Bouzard
Le 22/02/11 23:25, Eric Nelson a écrit :
I'm working from Tim Rudman's toning book and am playing with the FSA toner.
In it he lists thiourea dioxide to be used in the toning bath. Now I have
thiourea that comes from TechChem down in Missouri and called them to see what
flavor of thiourea I have. Bob called back and he found something odd in the
CAS listings.
TechChem's thiourea is CAS# 62-56-6
Thiourea dioxide has TWO CAS #'s which he says is "unheard of".
CAS# 4189-44-0 and CAS# 1758-73-2
Since Tim has been known to hang around these parts and others here may be more
familiar with the CAS catalog system, I'm wondering if these 3 compounds are
interchangeable or what?
Thanks
Eric
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