Sodium thiosulfate--anhy or penta?colourless crystalline

I just bought sodium thiosulfate from a chemical store. The label did not
indicate whether it was anhydrous or pentahydrate. I asked the store and they
said it was not indicated either. The chemical is from China. The detail is
only: sodium thiosulfate, 99% photo grade.

What I have here are big colourless crystals/granules. Does anyone here have
an idea whether this is anhy or penta? What are the differences in appearance
between sodium thiosulfate anhydrous and sodium thiosulfate pentahydrate?

I am still researching, but it will be a great help if someone here could
give me their advice. I hope someone can answer this question.

Thanks.

--
+Adelle ~

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QueenAdelle via PhotoKB.com wrote:

I just bought sodium thiosulfate from a chemical store.


The penta will chill the water when dissolved. Test
with a tbl spoon in 1/2 cup of room temperature water.
I think a drop of as much as 20 degrees F might be
expected. Dan

"QueenAdelle via PhotoKB.com" u15922@uwe wrote

I just bought sodium thiosulfate from a chemical store.
The label did not indicate whether it was anhydrous or
pentahydrate. The chemical is from China. The detail is
only: sodium thiosulfate, 99% photo grade.

Anhydrous chemicals are not all that common for photographic/
general use as they absorb moisture from the air and cake up.
If the chemical is to be added to water anyway there is no
reason to use the anhydrate, as such 'photo grade' will be
hydrated.

A good indicator is the packaging it comes in: if it is
a plastic bag/paper box/LDPE jar it is hydrated [or
soon will be].

What I have here are big colourless crystals/granules.

That's the normal hydrated photographic 'hypo'. Just
use it wherever hypo/thiosulfate is called for.

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation
http://www.nolindan.com/da/index.htm
n o lindan at ix dot netcom dot com

You have pentahydrate sodium thiosulfate, based on the physical description.

Try it in a fixer formula on that assumption. If fixing time is grossly
shorter than expected, then assume it is anhydrous, but I think not. It's
been a few years since nearly every photo store sold brown bags of the
pentahydate out of bulk as fixer, but it has a granulaer character you don't
forget.

"QueenAdelle via PhotoKB.com" u15922@uwe wrote in message
news:67662ed50109f@uwe...
I just bought sodium thiosulfate from a chemical store. The label did not
indicate whether it was anhydrous or pentahydrate. I asked the store and
they
said it was not indicated either. The chemical is from China. The detail
is
only: sodium thiosulfate, 99% photo grade.

What I have here are big colourless crystals/granules. Does anyone here
have
an idea whether this is anhy or penta? What are the differences in
appearance
between sodium thiosulfate anhydrous and sodium thiosulfate pentahydrate?

I am still researching, but it will be a great help if someone here could
give me their advice. I hope someone can answer this question.

Thanks.

--
+Adelle ~

Message posted via PhotoKB.com
http://www.photokb.com/Uwe/Forums.as...kroom/200610/1