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  #11  
Old 1st June 2021, 08:15 AM
Nat Polton Nat Polton is offline
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With the water test I appear to have pentahydrate.
Not what the label reads on the container.
Just a warning to anyone that has this on their shelf.


http://www.film-and-darkroom-user.or...1&d=1622535184


http://www.film-and-darkroom-user.or...1&d=1622535184


Cheers.
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  #12  
Old 1st June 2021, 08:21 AM
Nat Polton Nat Polton is offline
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Correction....

For the test, put a teaspoon of the sodium thiosulphate into a small glass and add a small amount of water to dissolve it.
Watch the temperature change on your thermometer.

I missed a few words out in the original text.

Cheers.
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  #13  
Old 1st June 2021, 04:54 PM
Michael Michael is offline
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That's disappointing, for a firm with Bellini's current reputation.
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  #14  
Old 2nd June 2021, 12:05 PM
Terry S Terry S is offline
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Quote:
Originally Posted by Nat Polton View Post
"This is available in two forms: crystalline (sodium thiosulphate pentahydrate) and anhydrous."

As mine is crystalline and cools when water is added I have the pentahydrate.

Well worth testing to see what you have before working out your quantities to use...
Totally unaware of the difference, as I only use hypo very rarely, I was curious to check if my two amounts from different sellers were in fact labelled correctly.

A small amount left in a tub from a Silverprint, did as said, rise in temperature, something I've never checked i.e. not known before, and yes it was labelled correctly as anhydrous.

A more recent order states it's purity and use, including photographically, but nothing else. It is in a lovely crystal form so fits the description given by Nat and the Darkroom Cookbook, which also states that the temperature should noticeably lower. Probably because I only used a small amount, the temperature seemed to stay the same.

My supplies are now marked, which will encourage me to look in the Darkroom Cookbook again when I use either of them, if my markings make no sense to me in the future.

I love the way I still learn new things when reading posts on FADU.

Terry S
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  #15  
Old 2nd June 2021, 12:16 PM
Lostlabours Lostlabours is online now
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Well I can buy 25kg of Sodium Thioslphate Pentahydrate for £110, where as 2.5 kg Sodium Thiosulphate is £203 nearly 20x as expensive.

Someone has miss-labelled the Thiosulphate at Bellini.

Ian
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  #16  
Old 2nd June 2021, 07:04 PM
Nat Polton Nat Polton is offline
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Why all the fuss? some may wonder.

From my old Rayco formula booklet,

Conversion rates.

Sodium thiosulphate
100 ANHYDROUS = 160 PENTAHYDRATE (CRYSTAL)

62.5 ANHYDROUS = 100 PENTAHYDRATE (CRYSTAL)


Important when mixing your own chemicals.

Cheers.
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  #17  
Old 2nd June 2021, 08:16 PM
Lostlabours Lostlabours is online now
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I wrote an updated Formulae booklet for Rayco some years ago, later I tried to buy the business, it had been sold the day, before,it wasn't a company by then rather a side part of a Pharmacy and the shop owners wanted the space for something else. While it had already been sold but never traded again.

At one time in the dim and distant past almost all pharmacies/chemists shops here in the UK sold phot chemicals etc. Boots were the largerest and even had their own Wood and Brass cameras, Jessops and Jacobs where both Leicester pharmacists first before becoming photographic chain stores.

I can remember in my youth buying film. paper and developer in a chemists shop in MAlvern, the gir gave me a special Universal developer to process my first 120 film - D163. Grain the sixe of bullets it wuld have been FP4, I had finer grain with FP3 in Promicrol, but hey you believed the selleer

Ian
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  #18  
Old 6th June 2021, 03:23 PM
Molli Molli is offline
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Quote:
Originally Posted by Nat Polton View Post
Why all the fuss? some may wonder.

From my old Rayco formula booklet,

Conversion rates.

Sodium thiosulphate
100 ANHYDROUS = 160 PENTAHYDRATE (CRYSTAL)

62.5 ANHYDROUS = 100 PENTAHYDRATE (CRYSTAL)


Important when mixing your own chemicals.

Cheers.
Thank you for that. While it was incredibly obvious that my thiosulpate was most definitely crystalline in nature, ergo pentahydrate, I did the temperature test 'just to see'. From 15°C to 9.4°C in a scant few minutes.
The labelling on my tubs doesn't specify either way, but the CAS number is different to yours. I've only just now opened one of the containers from an order placed last May. 2020, so it took five months to arrive from an hour up the road.
I was more concerned with its stated expiry date of May 2021 than checking to see which type I had.
Your original post, photographs, test and measurement conversions are all extremely helpful. Thank you.
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  #19  
Old 6th June 2021, 06:35 PM
Nat Polton Nat Polton is offline
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Thank you Molli and everyone else that helped.



Cheers.
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