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  #1  
Old 18th March 2012, 01:29 PM
robinb robinb is offline
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Default need some Sodium thiosulphate pentahydrate

Hi

I am trying to make a low bromide version of Dektol for reversal processing RA4 paper

Silverprint have everything I need except for 0.2g of Sodium thiosulphate pentahydrate
I have found a swimming pool supply company that will do me a 25kg bag but thats a bit more than I need ...

Can anybody direct me to somewhere that sells in much smaller quantities

regards

robin
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  #2  
Old 18th March 2012, 01:44 PM
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Richard Lee Richard Lee is offline
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Hi Robin,

I would suggest you try HERE. Good luck.

Regards,

Richard
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Old 18th March 2012, 01:53 PM
Mike O'Pray Mike O'Pray is offline
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Pity that it is only sold in what is still relatively large quantities for your needs. Even 1 Kg is 5000 processing sessions .

Mike
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Old 18th March 2012, 03:01 PM
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Domingo Domingo is offline
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Is its formula Na2O3S2.5H2O ? If so, I have some; how much do you need?
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Old 18th March 2012, 04:09 PM
robinb robinb is offline
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thanks for the replies

on further investigation it seems that Sodium thiosulphate pentahydrate is a crystaline version of Sodium thiosulphate
and that the 2 can be substituted so i will get some from silverprint
just need to remember that Sodium thiosulphate pentahydrate is weaker so will have to put less in

next problem is how to weigh such small quantities
my scale only go down to 1 g

robin
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Old 18th March 2012, 05:01 PM
Luis Luis is offline
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Quote:
Originally Posted by robinb View Post


next problem is how to weigh such small quantities
my scale only go down to 1 g

robin
Dissolve that g in 100ml, then use 20ml of this. This solution won't stand long, 1 or 2 days.

Last edited by Luis; 18th March 2012 at 05:07 PM. Reason: Cos I can
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Old 18th March 2012, 05:23 PM
Mike O'Pray Mike O'Pray is offline
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If you have need of scales for very small amounts of other stuff then apart from Muihlinn's suggestion use the FADU search facility. There was a thread on scales.

Silverprint sells scales which measure down to as little as 0.1g as well

Mike
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Old 22nd March 2012, 05:50 PM
Kat Barnett Kat Barnett is offline
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I bought some Digital Pocket Weighing Scales (0.1g-1kg or equivalent ounces) available as 'buy it now' from an online auction site. They cost 8.08 including the batteries and p&p. They do the job
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Old 22nd March 2012, 06:18 PM
Dave miller Dave miller is offline
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Quote:
Originally Posted by Kat Barnett View Post
I bought some Digital Pocket Weighing Scales (0.1g-1kg or equivalent ounces) available as 'buy it now' from an online auction site. They cost 8.08 including the batteries and p&p. They do the job
How did you check their accuracy?
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  #10  
Old 23rd March 2012, 08:25 AM
Luis Luis is offline
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most of such scales have an accuracy of 0.1, but they start counting much over it, so you'll have to use weighted weighting cups
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