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Photo Forum / Film Photography / Darkroom / May 2006Concentrated HCA From Powder
I've got a big 454g packet of Kodak HCA. I don't exactly have room for the 5 US gallons that it will produce. I've contemplated just weighing out 20 per cent and making 1 gallon. Is it possible to make the whole packet into a concentrate similar to other manufacturers' (e.g. Agfa 4-in-1), then dilute 1:31? Thx. You can mix it as a one gallon or 1.25 gallon concentrate and then dilute 1+4 or 1+3 for use. The liquid concentrates (with the 1+31 dilution) use a different composition. To get the 1+31 dilution ratio from concentrate you would need to dilute the whole package in 20 ounces of water (someone check my math it's still early here).  Signaturedarkroommike > I've got a big 454g packet of Kodak HCA. I don't exactly have room for the 5 > US gallons that it will produce. I've contemplated just weighing out 20 per > cent and making 1 gallon. Is it possible to make the whole packet into a > concentrate similar to other manufacturers' (e.g. Agfa 4-in-1), then dilute > 1:31? Thx. > I've got a big 454g packet of Kodak HCA. A pound of KHCA. Four one liter bottles should make for an easy fit. That stuff oxidizes quickly at working strength. Dilute at time of use only as much as needed. Bottles should be kept full. Perhaps do as I do and split to smaller full bottles as it is used. Considering the significant roll HCA plays in processing it needs to be treated with greater care. Keep your powder dry. If that pound were a homogeneous mixture you could spoon up a working strength just prior to use. Dan > I've got a big 454g packet of Kodak HCA. I don't exactly > have room for the 5 [quoted text clipped - 5 lines] > 4-in-1), then dilute > 1:31? Thx. This package is for 1 gallon of stock solution, the 5 gallon figure is for the working solution. Since the working solution has a very short lifetime its best to mix it as a stock solution and dilute it at the time of use. KHCA is mostly Sodium Sulfite, dessicated. The saturation at room temperature (70F) is about 270 grams per liter, the packaged product probably contains about 100 grams per liter in the stock solution. However, there are other chemicals in it. You could probably mix it at double the stock concentration if its kept at around room temperature. As Sulfite oxidizes it becomes Sodium Sulfate. Sulfate will do no harm but is inferior to Sulfite as a wash aid. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com > > I've got a big 454g packet of Kodak HCA. I don't exactly > > have room for the 5 [quoted text clipped - 10 lines] > solution has a very short lifetime its best to mix it as a > stock solution and dilute it at the time of use. As I turn...the package...over and read...the instructions...I now understand this...;^) (it's been two years since I mixed KHCA, I'd switched to Agfa...until recently) What is/was in Agfa's 4&1 stock solution? It was much more concentrated at 1:31. > KHCA is mostly Sodium Sulfite, dessicated. The > saturation at room temperature (70F) is about 270 grams per [quoted text clipped - 3 lines] > the stock concentration if its kept at around room > temperature. So maybe, if I'm lucky, I could have a 1.7 litre solution stock solution and then dilute 1:9 or there abouts. Too complicated. I'm thinking a heaping tablespoon (say, weight out 23.9g) in a litre for when I need to process film might be the way to go. Is it ok to just tightly reseal the packet as use as needed? > As Sulfite oxidizes it becomes Sodium Sulfate. Sulfate > will do no harm but is inferior to Sulfite as a wash aid. Thanks Richard. Alan Smithee spake thus: > So maybe, if I'm lucky, I could have a 1.7 litre solution stock solution and > then dilute 1:9 or there abouts. Too complicated. > I'm thinking a heaping tablespoon (say, weight out 23.9g) in a litre for > when I need to process film might be the way to go. Is it ok to just tightly > reseal the packet as use as needed? You might consider doing what I do, which is to simply use the main ingredient (sodium sulfite), in which case it's easy to do exactly what you proposed. I mix concentrate, but since the power is a single compound, you can measure it out dry as needed. I get mine from the local photo shop in resealable bottles from Lauder Chemical. You don't really need the other stuff that's in HCA. SignatureI hope that in a few years it [Wikipedia] will be so bloated that it will simply disintegrate, because I can't stand the thought that this thing might someday actually be used as a serious reference source. Because in its current form, it's not to be taken seriously at all. - Horst Prillinger (see http://homepage.univie.ac.at/horst.prillinger/blog/archives/2004/06/000623.html) Alan, I think you have a ONE gallon size package although the amount in it is a bit different from the bag I have in front of me now. Mine, bought only a couple of weeks ago, weighs 502 grams according to the label. It makes ONE gallon of stock solution which is then diluted 1 part stock to 4 parts water to make the working solution. You do NOT have a package for 5 gallons of _stock_ solution, rather this will produce 5 gallons of working solution when diluted at time of use. I would not try mixing only part of the powder for anything because the components are not always evenly distributed. In any case you don't need to do this. According to Kodak literature the life of the stock solution in a capped, filled bottle is about 2 months. Kodak is usually pretty conservative in their life estimates. Working solution does not last that long. Its good for perhaps 8 to 12 hours in an open tray and perhaps a week in a tank with a lid on it. Since there is no sign of oxidation (like turning brown) one can't tell if the stuff is good or not without some chemical analysis, too much trouble to bother with. For those with the materials on hand and desire to make their own the approximate formula for KHCA is: Wash Aid Stock Solution Water 750.0 ml Sodium Sulfite, dessicated 100.0 grams Sodium Bisulfite 20.0 grams EDTA Tetra Sodium Salt 5.0 grams Sodium Citrate 5.0 grams Water to make 1.0 liter Dilute 1 part stock to 4 parts water for use Target pH is 7.0 -- Richard Knoppow dickburk@ix.netcom.com I suspect also that Kodak's figure is more for a one gallon bottle, if you sub-divide the stock solution into smaller quantities, use glass bottles completely filled and use either good caps or cheap caps with a layer of "Saran" wrap PVDC (polyvinylidene chloride), (the new Saran wrap is not as good they changed the formula to LDPE but still seals pretty good). Signaturedarkroommike > Alan, I think you have a ONE gallon size package although the amount > in it is a bit different from the bag I have in front of me now. Mine, [quoted text clipped - 30 lines] > Richard Knoppow > dickburk@ix.netcom.com > ... if you sub-divide the stock solution into smaller quantities, > use glass bottles completely filled and use either good caps > or cheap caps with a layer of ... OR, pour or spoon up an appropriate amount of sodium carbonate at time of use. Agfa's recommended hca for many years; washing soda. Abandon all that hassel associated with a multi-component perishable hca. Off and on I've been testing the wash water with potassium permanganate looking to optimise the all-post-fix routine including the hypo clearing step/steps. As has many times been pointed out the permanganate test is not a test of the paper itself. It is though a test for the end or near end point in so far washing will achieve. The way I look at it now, the paper, baryta, and gelatin are distantly akin to the resins used in water softeners. Thiosulfate and argentothiosulfate ions attach to the three print components. A study by Martin Reed showed the baryta layer to be the slow to come clean component. If it were just paper and gelatin the wash would be done much sooner. As for testing the paper, the HT-2 test is the at home test. It is not sensitive enough to indicate AT archival levels. BUT, if the HT-2 test shows Zero stain it does indicate that archival levels have been approached. That is my reading. Dan dan.c.quinn@att.net spake thus: >> ... if you sub-divide the stock solution into smaller quantities, >> use glass bottles completely filled and use either good caps [quoted text clipped - 4 lines] > years; washing soda. Abandon all that hassel associated with > a multi-component perishable hca. What "hassle"? Only a hassle if one is a compulsive do-it-yourselfer like yourselfer, someone who evidently considers going into a photo shop and actually *buying chemicals* a sign of defeat or lack of manhood or something. Not a problem for the rest of us. SignatureI hope that in a few years it [Wikipedia] will be so bloated that it will simply disintegrate, because I can't stand the thought that this thing might someday actually be used as a serious reference source. Because in its current form, it's not to be taken seriously at all. - Horst Prillinger (see http://homepage.univie.ac.at/horst.prillinger/blog/archives/2004/06/000623.html) You missed the point, original poster already has a bag of HCA and wants to make it last but doesn't want to mix it to 5 gallons of working solution all at once. My suggestions had nothing to do with substitutions for HCA but with a way that OP could use the HCA he already has. When my stock of cheap HCA is gone (bought a few large bags on eBay a while back) I'll examine alternatives and will probably go to a dilute sodium sulfite solution, most of the other stuff in KHCA is to make it dissolve easier or keep longer in the jug. Signaturedarkroommike > > > > ... if you sub-divide the stock solution into smaller quantities, [quoted text clipped - 21 lines] > the HT-2 test shows Zero stain it does indicate that archival levels > have been approached. That is my reading. Dan > You missed the point, original poster already has a bag > of HCA and wants tomake it last but doesn't want to mix > it to 5 gallons of working ... I did not miss the point. You missed my first post this thread. Your and my posts addressing the OP's question are in agreement. My second post this thread broadened the subject some. My point is why put up with a perishable hca when washing soda, Agfa's recommended hca, is so close at hand and at time of use no problem to mix; a one ingredient hca. I'm quite sure Agfa makes/made that recommendation on some sound basis. Quite frankly I can't understand why anybody bothers with a perishable hca. I'd have to see some hard data supporting any contention that some other hca does a better job then sodium carbonate. Then I'd weigh any short comings against it's non- perishable character. Likely we are in the dark. I've found no hard data and it likely does not exist. Dan Hey Dan: Can you point me to some technical info about how much soda to use, times, final washes etc... Any difference between rc & fb? TIA -Lew > Hey Dan: Can you point me to some technical info about > how much soda to use, times, final washes etc... > Any difference between rc & fb? TIA - Lew From a quick Google search I found that Agfa recommends a 1% solution strength. I've not found much in specifics but a 20 minute wash after a 3 minute Agfa alkali soak was mentioned. I've not yet found the article but recent research by Michael Maunder published in issue 31 of Ag+ Journal does look to be worth reading. I'm not very trusting of research results from the 40s and 50s. Emulsion incorporated hardeners are now days the norm. According to Mr. Knoppow, Kodak's sulfite based KHCA was compounded, at least in part, so as not to interfere with the acid fixers and their included hardener. The two are carried forward to a pre-rinse or to the hca. Today most fixers are without hardener. At least Troop's TF-3 and 4 are very alkaline. Users of a carbonate hca aren't so rare as I had thought. Agfa was still recommending such when they closed up shop. Dan >My point is why put up with a perishable hca when washing soda, >Agfa's recommended hca, is so close at hand and at time of use no >problem to mix; a one ingredient hca. May 30, 2006, from Lloyd Erlick, I agree, but with a slight additional point. Many water supplies are on the hard side, so a small amount of Calgon (sodium hexametaphosphate or potassium citrate) or EDTA before adding the carbonate helps a lot. Even here in Toronto, where the water is not particularly hard, I get a bit of cloudiness if I attempt to dissolve sodium carbonate in tap water (I assume it is calcium carbonate precipitating). I'm quite sure Agfa makes/made >that recommendation on some sound basis. Richard Knoppow has addressed this question directly. He said Agfa's recommendation was quite old, dating from a time before the use of sodium sulfite was known to be superior as a washaid. Carbonate is OK, sulfite is better. I tend to use both, whichever is at hand. I bought a large bag of sodium carbonate for a very attractive price some time ago, so I guess I just use it. For some reason I use sulfite for film and often carbonate for paper. I wonder what Ansel Adams used before 1940?? regards, --le ________________________________ Lloyd Erlick Portraits, Toronto. website: www.heylloyd.com telephone: 416-686-0326 email: portrait@heylloyd.com ________________________________ |
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