Re: pentahydrate or anhydrous?

thanks everyone for your help. I purchased some pentahydrate sodium
thiosulfate today. As far as amount to use, the 5% solution (50grams
to 1000 ml water) which seems fairly common,would apply to
pentahydrate hypo?

david

On 21-Nov-05, at 6:33 PM, Eric Neilsen wrote:

> Richard, I don't know if very hot is really needed. My first
> experience with
> it certainly lead me to use warm water, but that is all that I
> found helped
> in my situation. If you were trying to use it straight way,
> perhaps, very
> hot may be required. 110F should be fine to start with as one mixed
> and if
> they found that it was still too cold they could turn up the heat.
>
> Eric Neilsen Photography
> 4101 Commerce Street, Suite 9
> Dallas, TX 75226
> 214-827-8301
> http://ericneilsenphotography.com
>
>> -----Original Message-----
>> From: Richard Knoppow [mailto:dickburk@ix.netcom.com]
>> Sent: Monday, November 21, 2005 10:55 AM
>> To: alt-photo-process-l@sask.usask.ca
>> Subject: Re: pentahydrate or anhydrous?
>>
>>
>> ----- Original Message -----
>> From: "BOB KISS" <bobkiss@caribsurf.com>
>> To: <alt-photo-process-l@sask.usask.ca>
>> Sent: Monday, November 21, 2005 5:19 AM
>> Subject: RE: pentahydrate or anhydrous?
>>
>>
>>> Good question!
>>> The photo lab index seems to suggest that most formulae
>>> which call for Hypo
>>> or Sodium thiosulfate but do not specify which flavor are
>>> referring to the
>>> pentahydrate...is this correct?
>>> CHEERS!
>>> BOB
>>>
>>> Please check my website: http://www.bobkiss.com/
>>
>> Formulas from old books generally specify crystalline
>> hypo, i.e., pentahydrate. I think this is because the
>> anhydrous variety was simply not available. Anhydrous works
>> fine in these formulas providing the weight is adjusted. If
>> anydrous is used the amount is 64% of crystalline.
>> One other difference is that crystaline hypo is very
>> endothermic so its mixed with very hot water. Anhydrous hypo
>> has little heat of solution so should be dissolved in room
>> temperature water.
>>
>> ---
>> Richard Knoppow
>> Los Angeles, CA, USA
>> dickburk@ix.netcom.com
>>
>>
>

david drake photography
daviddrakephoto@sympatico.ca
Received on Mon Nov 21 20:43:24 2005