bleaching prints w/ potassium ferricyanide

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Howdy, I've been having some problems with areas that I've given a lot of bleach to in my prints lately. Usually I will use a water/potassium ferricyanide solution on areas (such as eyes) that need to be brighten up, etc, and I've been getting yellow stains in the areas that I've really concentrated on lately. Different people have given me different explanations so I'm still kind of in the dark (forgive the pun)... I have been going from a two or three minute fix, giving the print a cursory wash off, and then bleaching. Should I increase wash time? Someone told me that the bleach is reacting with fix still in the emulsion. I don't know if I believe them or not. It is kind of inconvenient for me to go through the whole HCA, wash, etc. procedure before bleaching, becuase I like to work on it as I print and that way when I botch one everything is set up for the next print... you get the idea... What about farmer's reducer? Is there a good source (i.e. book/website) on this? I would appreciate any information y'all could give. Thanks

-- Frank Miller (fmiller4@gtwn.net), September 12, 1997

Answers

Bleaching prints.

Have you changed anything in your procedure, even slightly (ie temperature)? I have heard that you have to wash fairly well before using a reducer. I believe Farmer's is used alot for this purpose. I think the inconvenience of experimenting with a longer wash would be less than having to reprint.

-- Andy Laycock (pbrlab@unixg.ubc.ca), September 12, 1997.

Check out the Nov/Dec 96 issue of Photo Techniques. Bruce Barnbaum has an article on this subject. He also touches on it in his "The Art of Photography" book. have you changed papers? Some stain more readily than others. Anyway, check out the articles & I hope they help. Also, PT is an excellent magazine.

-- Dan Smith (shooter@brigham.net), September 12, 1997.

Re: bleaching prints

Use a NON-HARDENING fixer to avoid stains. The formula for F-24 is found in Steve Anchell's indespensible "The Darkroom Cookbook." In this book, you will also find formulas for bleach. A more dilute bleach will work more slowly, but must still be washed out COMPLETELY. But my real question is why are you bleaching areas like eye shadows? Try dodging, ala Richard Avedon. Much easier, cheaper, and controllable! No messy stains, either.

-- Michael D Fraser (mdfraser@earthlink.net), September 13, 1997.

response to bleaching

Hi Frank,

Sodium Thiosulfate (hypo, part B in Farmer's reducer) will help inhibit the "bleach" and help prevent over bleaching, which creates those stains. You can alternate the print between hypo and bleaching surface. OR you can mix both parts of Farmer's in 4 oz. h2O instead of 16 oz. (keep separate), which is 9.2 grams Pot. ferri. with 500cc H2O and 74 grams Sod. Thio. with 500cc H2O. Note: this is a very strong bleach that works well with Polymax but will have to be diluted with H2O for most other papers. Once the two parts are mixed together it will only remain potent for about 10 minutes. Email me if you have problems or questions. -Doug

-- Doug McSpadden (mcspadden@mcn.net), September 14, 1997.


bleaching

I use bleaching as an everyday tool in printing. There are many methods recomended. One that I dont is the use of Farmers reducer as a print bleach. Simply because its not truly constructed for that purpose. Your problem seems to simply be that you are mixing the PF much to strong. Either mix a much weaker solution or allow the mixture to "age" prior to use. I keep 3 mixtures set up at all times , one ,two & three days old. The older they get the greener they become, but also the weaker. Also ,I dont recomend that you wash at all prior to area bleaching. Perform this task during the fixing process It is also a good idea t not use a hardner in the fix.

-- jim megargee (mvjim@interprt.net), October 11, 1997.


I believe that bleaching with Farmer's Reducer may solve your problem. Farmer's Reducer has two parts, A and B. Part A is ferricyanide and part B is an anti-yellow stain chemical (I don't have any Farmer's Reducer handy and I don't remember the name of the chemical but I know that the purpose it serves is to reduce yellow stains). I would suggest mixing each part in a ratio of 1 part chemical to 4 parts water, rather than the 1 - 16 suggested in the instructions. 1 - 16 is quite weak. Also make sure that each part is mixed in equal quantities - if you err at all, err on the side of getting too much part B - too much part A will tend to result in a yellow stain, which is what you are trying to avoid. I don't offhand know of any websites relating to bleaching but there is a fairly long article on bleaching by Bruce Barnbaum in the November/December, 1996 issue of the magazine "Photo Techniques."

-- Brian Ellis (bellis@fowlerwhite.com), December 04, 1997.

In my previous response I forget to mention one other point concerning your staining problem. Some papers are more susceptible to staining than others. For example, Ilford MGIV fiber base tends to stain quite easily in my experience.

-- Brian Ellis (bellis@fowlerwhite.com), December 04, 1997.

staining is a common problem when post processing B&W prints. It is always very important to thoroughly wash prints between use of ANY chemicals on your papers. This is vital. Stains can be eliminated by usinga solution of Thiorea (Thiocarbamide) and Citric Acid. About 10% solution of the former and 5% solution of Citric. These are readily available and should be in your range of chemical s for toning. Thiorea toning gives a range of colours through browns, and yellow browns to chocolate....in this case of toning it is much easier than sulphide toning and not smelly. When toning a base is added to the thiorea, sodium hydroxide, instead of the acid.

As a stain remover it cannot be beaten. Again do wash thoroughly (..as the vicar said to the showgirl.)

-- david Strachan (strachan@cww.octec.org.au), January 28, 1999.


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