shakti v. Posted October 7, 2006 Share Posted October 7, 2006 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. Link to comment Share on other sites More sharing options...
ann_clancy6 Posted October 7, 2006 Share Posted October 7, 2006 you have the pentahydrate version. anhydrous is powder. you have to convert the amounts if a formula calls for one type and you have the other. when using pentahydrate and the formula indicates anhydrous multiply by .64 Link to comment Share on other sites More sharing options...
larrydressler Posted October 7, 2006 Share Posted October 7, 2006 Ann My thought as soon as he said BIG. Larry Link to comment Share on other sites More sharing options...
shakti v. Posted October 8, 2006 Author Share Posted October 8, 2006 Thank you so much for your help. I have posted another question about fixers. I hope you will read also. Link to comment Share on other sites More sharing options...
john_stockdale2 Posted October 10, 2006 Share Posted October 10, 2006 Crystals would indicate pentahydrate. Also, when the pentahydrate is dissolved in water, a lowering of temperature is observed. You could use this as confirmation. The pentahydrate contains "water of crystallization" and hence is less concentrated than the anyhydrous. If a recipe calls for anyhydrous, and you have crystalline (pentahydrate) you need more. Multiply the amount in the recipe by 1.56 (in other words, divide by 0.64). I'm not sure if that was expressed clearly in a post above. Link to comment Share on other sites More sharing options...
shakti v. Posted October 10, 2006 Author Share Posted October 10, 2006 John, thank you. I got that. Yes, I have penta. I also used the conversion to make ammonium thiosulphate= 600 g ammonium chloride + 1406g sodium thiosulfate (using division by 0.64; 900g in anhy), in 1.5 L of water. To those interested, I made a post about my process in making TF-3 alkaline fixer. Please post comments and suggestions on that thread. Gracias. Link to comment Share on other sites More sharing options...
profhlynnjones Posted October 13, 2006 Share Posted October 13, 2006 Teh answer is 64%. We always bought anhydrous at 64 lb bags to be equivalent to 100 lb of penta. I used to be lab supervisor for a Kodak licensed motion picture lab and learned lots of neat stuff. Lynn Link to comment Share on other sites More sharing options...
andrew_hoi Posted September 23, 2009 Share Posted September 23, 2009 <p>Hi Shakti,<br> I aslo buy sodium thiosulfate (pentahydrate ) from china.<br> Can you mixed the fixer normally ?<br> Also can you give me the recipe of the fixer in detail ? I am newby and interest in this topic.</p> <p>THX</p> <p>Andrew</p> Link to comment Share on other sites More sharing options...
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