sanking said:
Tom,
Are you mixing Michael Smith's Amidol formula as a concentrated stock solution and then diluting with water to make the working solution? I have read your previous description of this but am still a bit confused as to exactly how you are mixing the stock and working solutions. I would really appreciate it if you would describe this again as I would like to try this myself as it sounds like a much better way of working than having to mix the developer from scratch every time.
Thanks in advance.
Sandy
Sandy, this formulation has been evolving. Here is my current procedure:
The basic formulation is Michael Smith's Azo contact paper developer formulation, so: 30 grams/liter sodium sulfite, 3 grams/liter citric acid, 2ml 10% KBr/liter. Michaels Azo formulation calls for 8 grams/liter Amidol.
I have determined that I can dissolve 8 grams of Amidol in 250 ml of Propylene Glycol (PG) at 140 to 160 degrees F. A very small amount of undissolved Amidol debris (typically a fraction of a gram) will be left that will eventually settle to the bottom of the container. This Amidol debris is water-soluble and has not affected the end results with the working developer. I have raised the PG temperature to 250 F and the debris remains insoluble however, the debris dissolves easily in water at room temperature.
I mix the Amidol stock solution under a vented laboratory hood on a combination hot plate/magnetic stirrer.
MS Amidol Concentrate Solution A
Propylene Glycol at 160 deg F --------------------------900 ml
Amidol --------------------------------------------------32 grams
Stir until dissolved (some undissolved residue is normal)
Propylene Glycol to -----------------------------------1000 ml
MS Amidol Concentrate Solution B
Water at 125 deg F -------------------------------------800 ml
Sodium Sulfite ------------------------------------------120 grams
Citric Acid -----------------------------------------------12 grams
10% KBr stock solution ------------------------------------8 ml
Water to ----------------------------------------------1000 ml
For working developer: Mix 1 part A + 1 part B + 2 parts water