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Photo Forum / Film Photography / Darkroom / January 2005silver deposits
my developing tray has a fair amount of silver deposits on it. will that affect developing time at all, or is it still good?  Signaturehttp://www.neopets.com/refer.phtml?username=moosespet > my developing tray has a fair amount of silver deposits on > it. will that > affect developing time at all, or is it still good? The deposits may be metallic silver or silver sulfide. They generally do no harm. They can be removed with a couple of bleaches. The old standby is Potassium dicromate and Sulfuric acid. Ready mixed cleaner used to be easily available but is no longer because of the hazardous nature of the ingredients. You may have good luck using plain household bleach followed by fresh hypo, followed by a water wash. Developers vary in their tendency to make such deposits. Dektol generally does, Agfa's Neutol Plus does not deposit silver. Give the bleach a try and let me know if it works. For those interested in the old style cleaner here it is: Kodak Tray Cleaner TC-1 Water 1.0 liter Potassium dichromate 96.0 grams Sulfuric acid, concentrated 90.0 ml Add the acid slowly to the water with constant stirring. Sulfuric acid evolves a lot of heat when dissolving and can splatter if added too quickly. Both the acid and the dichromate are very hazardous and must be handled with great care. The mixed solution is much less hazardous but you should avoid coming in contact with it. Use full strength. Pour some in the container to be cleaned and swirl it around until the silver stains disappear. Then rinse well with water. The cleaner can be re-used until it stops working. I've used it until it was black and it still did a good job. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com Richard, you could know this without much head-scracthing... what's the best way of separating silver from the developer? i've got some pretty large volumes of old developer from the times when my father was doing loads of darkroom work and i'm trying to find out the best idea of disposing them :) i know yields would be pretty low to be profitable... but i would have some fun at least and maybe the final products might be more safe to dispose thanks :) Signaturedeejay <... >Richard, > >you could know this without much head-scracthing... what's the best way of >separating silver from the developer? Why not try electroplating it out? Signatureregards from :: John Bartley 43 Norway Spruce Street Stittsville, Ontario Canada, K2S1P5 ( If you slow down it takes longer - does that apply to life also?) I know that Porter's canera carries an electrostatic precipitator kit. It even has an envelope to send the collected silver to a recycler for $$. http://buyporters.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=PCS&Product_ Code=22-1063&Product_Count=&Category_Code= >>Richard, >> >>you could know this without much head-scracthing... what's the best way of >>separating silver from the developer? > > Why not try electroplating it out? heh, a nice idea... i think i'll give it a thought or two porter's is u.s.-based though Signaturedeejay >I know that Porter's canera carries an electrostatic precipitator kit. It >even has an envelope to send the collected silver to a recycler for $$. [quoted text clipped - 6 lines] >> >> Why not try electroplating it out? > you could know this without much head-scracthing... what's > the best way of separating silver from the developer? There is no silver in developer. There is image silver and what silver remains is left in the fixer. Dan sorry, a occassional result of my multithreading :) typing sent to background process so i could think of something else during that... sometimes the two processes interfere though... i of course meant the fixer Signaturedeejay >> you could know this without much head-scracthing... what's >> the best way of separating silver from the developer? > > There is no silver in developer. There is image silver > and what silver remains is left in the fixer. Dan >> my developing tray has a fair amount of silver deposits on it. will that >> affect developing time at all, or is it still good? [quoted text clipped - 4 lines] > easily available but is no longer because of the hazardous nature of the > ingredients. [snip] Richard, Tetenal markets a product here in Europe called EXARGENT, a 5 - 10% Thiourea and 1 - 5 % Sulfamic Acid solution. I used it on some silver deposits (metallic by the looks of it) left behind in a Ilford CAP-40 processor and it was very effective. What would be your recommendation on something like this? Seems to be less of a hazard than the dichromate. Jim >>> my developing tray has a fair amount of silver deposits >>> on it. will that [quoted text clipped - 19 lines] > > Jim I have no experience with this but just about any packaged product is less hazardous than the ingredients for the tray cleaner. Other suppliers of color processing chemicals also offer system cleaners which are likely the same thing although some of them are our old friend dichromate. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com Ephraum's book on b&w suggesting using citric acid. Haven't tried it yet, but considering how easy it is for me to get, I will give it a try. If a friend did not have some to give me, I would just use a bottle of lemon juice, or check with a homebrewing shop. PSsquare > my developing tray has a fair amount of silver deposits on it. will that > affect developing time at all, or is it still good? > Ephraum's book on b&w suggesting using citric acid. > Haven't tried it yet, [quoted text clipped - 9 lines] >> on it. will that >> affect developing time at all, or is it still good? Rapid fixer with citric acid added is a mild silver solvent. The mixture recommended by Kodak for removing dichroic fog from film is film strength rapid fixer with citric acid added at the rate of 15 grams/liter. This may not be strong enough to remove silver from trays and tanks but its worth a try. Probaby rapid fixer stock with the citric increased in proportion would be better. Again, its certainly less hazardous than dichromate cleaner. The only cleaner I am not in favor of is the mild abrasive kind now popular. Eventually these will destroy the shiny surface of plastic trays causing a much worse staining problem. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com > my developing tray has a fair amount of silver deposits on it. will that > affect developing time at all, or is it still good? I find that if I wash out the trays with hot water after every developing session (i.e., never leaving it in overnight), I never get silver deposits. Signature.~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 12:40:00 up 15 days, 2:00, 3 users, load average: 4.20, 4.10, 4.09 ... >I find that if I wash out the trays with hot water after every developing >session (i.e., never leaving it in overnight), I never get silver deposits. ... jan1505 from Lloyd Erlick, Cleanliness is next to ...?? Since I've been working single-tray, this is an automatic consequence. However, I am not godly about it. regards, --le Signature________________________________ Lloyd Erlick Portraits, Toronto. voice: 416-686-0326 email: portrait@heylloyd.com net: www.heylloyd.com ________________________________ -- On 1/14/2005 9:02 PM Jon Pike spake thus: > my developing tray has a fair amount of silver deposits on it. will that > affect developing time at all, or is it still good? My suggestion is to take the easiest way here: don't worry about the deposits. They don't affect development in the least, as they are precipitates that don't go back into solution. Unless they really bother you esthetically, just ignore them. SignatureToday's bullshit job description: • Collaborate to produce operational procedures for the systems management of the production Information Technology infrastructure. - from an actual job listing on Craigslist (http://www.craigslist.org) |
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