Recognize this HCA recipe?
I recently realized that the HCA formula I've been using for some years (for prints) isn't in my list of HCA formulas that I show in my spreadsheet compilation.... I can't recall where I got it but remember in testing back then, that it was effective and I trust it. I had simply listed the recipe on the bottle that I mix it to. Does this look familar to anyone?
For 1 liter, diluted 1:9 for use.
Sodium Sulfite 200g
Sodium Bisulfite 40g
Sodium Citrate 10g
EDTA Tetra Sodium Salt 10g
I really shouldn't be too paranoid about this but I'm usually quite thorough in my record keeping and realize that I don't seem to have a trail on this one like I should. The recipes that I have are varied and generally show quite a bit less Sodium Citrate and EDTA if they are included at all. Lacking a concrete source now has me second-guessing my label recipe. Any thoughts?
2% Sodium Sulphite works just as well. The EDTA will help with some hard water. It's not that critical it's not a hypo eliminator just an aid for shortening wash times.
Last edited by Ian Grant; 09-15-2008 at 02:19 PM. Click to view previous post history.
It looks a lot like Richard Knoppow's "believed to be" close to the Kodak, but double strength (1+9 for working strength) instead of 1+4. I mix it double strength too, making it easier to store.
This quote either from rec.photo.darkroom or pure-silver:
<start of quote>The purpose of the sequestering agents is to eliminate a tendency of the sulfite bath so form a sludge with alkaline salts in the water, probably not necessary when the wash aid bath is not used to its capacity. You can make your own wash aid. The formula below is not official but is pretty close to what is in KHCA.
Sodium Sulfite, dessicated 100 grams
Sodium Bisulite 20 grams
EDTA tetra-sodium salt 1 gram
Sodium Citrate 1 gram
Water to make 1 liter
The above is a stock solution. For use dilute one part stock to four parts water.
<end of quote>
RK has said that there is some doubt in his mind about the citrate and EDTA levels. He said he didn't know if his figures for these were pre- or post- dilution.
The quantities of citrate and EDTA in your formula are different. Ryuji Suzuki also had a formula with different amounts of these two minor ingredients, and I think Wolfgang Moersch here at APUG had yet another. Maybe it can be found.
Last edited by john_s; 09-16-2008 at 04:46 AM. Click to view previous post history.
Reason: Probably makes more sense.
The formula suggested by Wolfgang Moersch is part of the way down this thread:
And from Ryuji Suzuki's web site a similar formula (working strength):
<start of quote>
A standard washing aid is:
sodium sulfite 15g
sodium metabisulfite 5g
water to make 1.0 l
target pH 6.5 to 8
When scum is formed on the solution or processed material, addition of about 0.5g/L of disodium or tetrasodium EDTA with about 1.0g/L of sodium citate is suggested. Stock solution including the EDTA and citrate tends to keep longer.
Kodak Hypo Clearing Agent contains EDTA and sodium citrate to reduce the calcium scum. With hard water, sulfite in the wash aid forms insoluble calcium scum unless EDTA is added. These are also useful in preventing precipitation of aluminium hardener that may be carried over from the fixer (if acid hardening fixer is used).
<end of quote>
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