Ammonium thiosulfate teaspoon amount for TF-3?

greenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread

I have ammonium thiosulfate (anhydrous?) crystals, and I want to make TF-3 Alkaline Rapid Fixer. The recipe calls for a 57-60% solution of amm. thio. which I believe I would make by adding 57-60g to a liter of water. But I don't have a scale, and the metric/teaspoon conversion isn't listed in THE COOKBOOK. So does anyone know how many grams equal one teaspoon? Also, has anyone successfully modified the recipe to lessen the ammonium

-- TJ Black (tjtexas@hotmail.com), April 21, 2002

Answers

The last sentence should read: Has anyone successfully modified the recipe to lessen the ammonium odor

-- TJ Black (tjtexas@hotmail.com), April 21, 2002.

I can't help the teaspool measure part. Ammonium thiosulfate is said to be unstable in dry form, so I usually keep 60% solution. The odor can be reduced by removing sodium metaborate and adding boric acid (and some borax if needed - I don't use borax). If you don't mind a bit of acetic acid smell, you can use sodium acetate buffer. Unless you need absolutely high pH to keep the stain from staining developer, target at pH of 6 to 7. For quick efficient wash and negative stability, you don't have to go too alkaline. But before trying all these, I recommend finding a decent scale - check out www.balances.com. Also, decent sets of pH test strips are handy and good for sanity check before using the solution too (one for pH of 4 to 8 range for fixers and another for pH of 8 to 12 for developers would be good).

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), April 21, 2002.

"The recipe calls for a 57-60% solution of amm. thio. which I believe I would make by adding 57-60g to a liter of water."

Hey! One liter of water is 1000 grams, and 60% of 1000g is 600g, not 60g. 60g is only 6% of 1000g.

-- Patric (jenspatricdahlen@hotmail.com), April 21, 2002.


Moderation questions? read the FAQ