Kodak H.C.A. Formula
Kodak's list of chemicals on a package of Hypo Clearing Agent
75-80 Sodium sulfite (007757-83-7)
15-20 Sodium metabisulfite (007681-57-4)
1-5 Sodium citrate (000068-04-2)
1-5 Ethylenediaminetetraacetic acid tetrasodium salt (E.D.T.A.)
To Make 1 Gallon/ 3.8L of H.C.A. Stock (to be mixed 1/4 with water for the working solution):
Assuming that Kodak didn't want to reveal its exact formula, the company listed the chemicals with varied percents. By roughly adding the ingredients to make 100, this is what I mix to make a stock solution. The amount of E.D.T.A. is significantly increased. The stock is diluted 1/4 to use for processing film or prints.
Into 3 quarts/ 2.8L of water (120°F / 50°C) add each ingredient, stir until dissolved. After all the chemicals have been added and in solution add water to total volume, 1 Gallon/ 3.78L.
Sodium Sulfite 360 grams
Sodium Metabisulfite 65 grams (Opional)
E.D.T.A. 50 grams
Sodium Citrate 25 grams
Many chemical suppliers don't carry Sodium Metabisulfite. Photographer's Formulary does but here's an alternative formula that I have also used for years when I couldn't find Sod. Meta. in Finland.
Sodium Sulfite 425 grams
E.D.T.A. 50 grams
Sodium Citrate 25 grams
Photographer's Formulary Link - http://stores.photoformulary.com/