Photogtaphy Forums

Photography Forums > Photography Newsgroups > Photography Archive > Darkroom Developing and Printing > Sodium thiosulfate--anhy or penta?colourless crystalline

Reply
Thread Tools Display Modes

Sodium thiosulfate--anhy or penta?colourless crystalline

 
 
QueenAdelle via PhotoKB.com
Guest
Posts: n/a

 
      10-07-2006, 08:15 AM
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

 
Reply With Quote
 
 
 
 
dan.c.quinn@att.net
Guest
Posts: n/a

 
      10-07-2006, 10:02 AM
RE: 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

 
Reply With Quote
 
 
 
 
Nicholas O. Lindan
Guest
Posts: n/a

 
      10-07-2006, 01:40 PM
"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


 
Reply With Quote
 
Randy Stewart
Guest
Posts: n/a

 
      10-07-2006, 03:34 PM
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
>



 
Reply With Quote
 
 
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Question: Shooting under sodium vapor lights PTravel Professional Video Production 55 07-06-2006 08:16 AM
Sodium Lighting Andy Photography 4 10-16-2003 11:47 PM
FG-7 w/Sodium Sulfite Craig Schroeder Darkroom Developing and Printing 7 08-11-2003 01:11 PM
Sodium carbonate solution - how long does it keeps? Jorge Omar Darkroom Developing and Printing 12 07-22-2003 03:15 PM
Sodium Ascorbate ATIPPETT Darkroom Developing and Printing 7 07-11-2003 01:25 PM