[pure-silver] Re: Thiourea and Thiourea dioxide
- From: "Eric Neilsen" <ej@xxxxxxxxxxxxxxxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 24 Feb 2011 10:42:43 -0600
The lines in the figure indicate bonds. Two lines = double bond which means it
requires more energy to release. That OH group probably comes off easily or
easier than the other groups. With seeing the whole process, ions running
around, etc I won’t even go any further. Not that I am totally qualified to do
so either. pH can be a big issue in making toning happen as it put in motion
the bonding that will or can take place. The different CAS # may be ( just a
guess) due to a registration by the one company with its name. If the formula
calls for FAS – the later two, it may be a pH issue.
(NH2)2.CS from JT baker
The other two sources.
CH4N2O2S
· CH4 N2 O2 S
<http://www.lookchem.com/300w/2010/0621/4189-44-0.jpg> Molecular Structure of
4189-44-0 (Methanesulfinic acid,1-amino-1-imino-)
Good luck.
Eric Neilsen
4101 Commerce Street, Suite 9
Dallas, TX 75226
214-827-8301
<http://ericneilsenphotography.com/forum1> Let's Talk Photography
www.ericneilsenphotography.com
SKYPE ejprinter
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Gerald Koch
Sent: Thursday, February 24, 2011 8:37 AM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Thiourea and Thiourea dioxide
Sodium bisulfate (sodium hydrogen sulfate) can be substitued for sulfuric acid
in many photo formulas. It has the afvantage of being a solid and hence safer
to use than the acid. It can be obtained from many sources. It ir sold as
pH-Minus for adjusting the pH of swimming pools.
Jerry
_____
From: Eric Nelson <emanmb@xxxxxxxxx>
To: pure-silver@xxxxxxxxxxxxx
Sent: Thu, February 24, 2011 9:14:41 AM
Subject: [pure-silver] Re: Thiourea and Thiourea dioxide
I used the iodide version as I had the chemicals for that; I don't have
sulphuric for the other bleach. Using the iodide bleach once you see the image
starting to lighten, it's pretty much time to pull the print as the toner
doesn't add density in my case and perhaps it was because I was using RC paper.
Also the tip in Tim's book of re-bleaching (if I don't like the results of the
toner) and then putting back into a developer (assuming dektol etc was meant)
didn't work here either.
Of course looking at the chemical formula for TD vs my thiourea I see that they
look very different so thhat may explain a lot, but what that means chemically
I have no idea.
Eric
_____
From: "C.Breukel@xxxxxxx" <C.Breukel@xxxxxxx>
To: pure-silver@xxxxxxxxxxxxx
Sent: Thu, February 24, 2011 7:30:34 AM
Subject: [pure-silver] Re: Thiourea and Thiourea dioxide
Hi Eric,
I am surprised here: FSA is my favorite toner. I use it mostly on partially
toned prints, because the density gain is considerable (your image can get 1-1
½ stops darker on a completely bleached print, depending on the paper). I like
the flexibility of the different bleaches.
Redevelopment (FSA is not really a toner, see Tim’s book) in FSA is generally
very fast: 30 sec-1 min., exception is after the Iodine bleach, than
re-development takes a lot of time (by heart: 30 minutes or so)
Good luck,
Cor
Btw my FSA http://tinyurl.com/669jflo
Good luck,
Cor
_____
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Eric Nelson
Sent: woensdag 23 februari 2011 21:45
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Thiourea and Thiourea dioxide
It worked ok-ish in that I did get toning eventually; it's very slow, and if
you bleach too far tone doesn't come back as it does when sepia toning.
It is a totally different process, and I understand that. The color I got was
nice yellow-greenish brown.
What I'd really like to find is a toner (besides tea and coffee) that adds a
cream color to the paper. Presently just working with RC postcard paper so
extended toning and washes aren't a best choice although w/RC I assume longer
washes aren't necessary anyway. I'd just hate to send out a promo and have it
turn brown.. i.e. brown in a bad way!
Eric
_____
From: Ray Rogers <earthsoda@xxxxxxxxx>
To: pure-silver@xxxxxxxxxxxxx
Sent: Wed, February 23, 2011 11:50:52 AM
Subject: [pure-silver] Re: Thiourea and Thiourea dioxide
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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