Survival Chemicals
From Silvergrain Research
There are some common household products that can be used as an ok source for photographic chemicals to mix processing chemicals. Needless to say, it is better to purchase photographic grade chemical stocks from photographic chemistry suppliers [1] or laboratory chemical supply houses, such as Sigma-Aldrich. There is also amateur chemical supplier [2] but their selection is limited and their shipping cost is high.
Emulsion making requires far greater degree of purity than those technical grade stocks, and it is preferred to use analytical grade stocks.
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Sodium hydroxide
Red Devil Lye is a reasonably pure sodium hydroxide, suitable for most darkroom purposes.
Sodium bicarbonate
Also called sodium hydrogen carbonate and baking soda. Arm & Hammer Baking Soda is USP (pharmaceutical) grade sodium bicarbonate and suitable for darkroom use.
Sodium carbonate
Based on my own tests, Arm & Hammer Super Washing Soda is monohydrate form of sodium carbonate. It is probably comparable to technical grade, but it is suitable for most darkroom applications including developers.
Very high quality sodium carbonate can be made from sodium bicarbonate by heating it in a crucible furnace, or more conveniently an enameled pot, with good stirring. The white powder will change its consistency and color during heating. Overheating is close to impossible with regular enameled pot on gas stove. If heating in oven is preferred, use 400F or higher and make sure the powder is exposed to this temperature for long enough. Heating in this procedure can be safely overdone, as long as the container is safe. The resulting sodium carbonate is anhydrous, which is more potent than monohydrate form. This form is hygroscopic, and also readily absorb carbon dioxide gas from air, so keep it in a air-tight container. If the anhydrous carbonate goes stale, you can reheat as above to get the anhydrous carbonate again.
Borax
Borax is a common name for sodium tetraborate decahydrate. 20 Mule Team Laundry Booster is pure enough for darkroom use.
Ascorbic acid
Vitamin C powder sold as nutritional supplement is USP grade L-ascorbic acid. Tablets should be avoided because they contain fillers and weigh more. Tablet fillers may not be inert in developer solution, and they are also hard to dissolve.
