Hi,
Since hypo clearing agent is not very stable, and can only be used for one printing session, I want to make my own from scratch, rather than buy concentrate. Is sodium sulfite the only component? What concentration is hypo remover usually used at?
Fred
Most commercial wash aids are a mixture of sodium sulfite and sodium bisulfite, likely proportioned to give neutral pH. Plain sulfite works fine, though, and will leave the emulsion in a slightly alkaline state which can further enhance the washing rate (especially important for fiber prints). I use 20 g/L sodium sulfite in filtered (ion exchange filter, made for drinking water) or distilled water, nothing else, and discard after one session. Takes only a couple minutes to mix the sulfite into the water at room temperature; less time than required for the hypo crystals to dissolve for my fixer.
If a contact print at arm's length is too small to see, you need a bigger camera. :D
Here is a formula that supposedly is similar to Kodak Hypo-Clearing Agent:
Hypo Clearing Agent
Water 1 Liter
Sodium Sulfite 20 g.
Sodium Bisulfite/Metabis. 0.2 g
This works out to roughly one Tablespoon of sodium sulfite plus a pinch of bisulfite of metabisulfite per liter. While I am a stickler for accuracy when mixing most developers from scratch, the spoon recipe for hypo-clear is more than accurate enough and saves me from having to drag out the scales.
The sodium bisulfite/metabisulfite is only in the formula to lower the ph to 7-7.5 to prevent softening of the film. I often use just the sulfite, since it works just as well, and most modern films are pre-hardened anyway.
Note: A stock solution can be made by adding ten times the dry ingredients to 1 liter water. This is then diluted 1:9 for use. However, I find one-shot spoon recipe use to be easiest.
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