Fulgencio Martinez Posted February 6, 2004 Share Posted February 6, 2004 I´m starting myself into home processing. Wonder if anyone has tried developing B/W reversal without the bleach. Are the results similar to the color neg bleach bypass. Will i have more contrast, grain and speed or just ruin my film. Thanks, Fulgencio Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted February 7, 2004 Premium Member Share Posted February 7, 2004 There IS no bleach step in processing b&w film anyway so in effect you are always "bypassing" it. Do you know what the bleach step does in the first place? When you expose color film, the silver halides grains that receive light become "developable" -- i.e. hold a latent image. When color film is developed, an equal amount of color dye is formed along with the metallic silver. To then remove the silver, the bleach step reconverts it to silver halide, as if it were never exposed (all the unexposed areas of the frame remain silver halide.) The fixer and wash steps then removes all the unexposed silver halide, leaving only color dye. So skipping the bleach steps leaves the metallic silver unconverted to silver halide and therefore it never gets removed by the fixer and wash steps. Link to comment Share on other sites More sharing options...
Fulgencio Martinez Posted February 7, 2004 Author Share Posted February 7, 2004 Hi David, I´m talking B/W reversal and there is a Bleach step in it´s processing Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted February 7, 2004 Premium Member Share Posted February 7, 2004 Wouldn't you essentially be cross-processing it then -- not "reversing" the image? Link to comment Share on other sites More sharing options...
Fulgencio Martinez Posted February 7, 2004 Author Share Posted February 7, 2004 Regular process for b/W reversal is. Developer-Bleach-rexposure-developer-fix The bleach bath involves sulfuric acid. I wonder if taking the bleach out will give similar results in contrast like when you do it in a color process. Maybe not doing the bleach will cause bad rexposure. Did anyone try before? Link to comment Share on other sites More sharing options...
Mitch Gross Posted February 7, 2004 Share Posted February 7, 2004 You can do it and essentially turn your B&W reversal stock into a negative stock, but it will be very contrasty since the stock was designed with projection contrast gamma, not neg. contrast. It won't be particularly grainy, although in trying to get a print through that high con neg. you'll probably introduce a lot of grain. I did this once as an experiment years ago. The results were not particularly useful. Link to comment Share on other sites More sharing options...
Fulgencio Martinez Posted February 7, 2004 Author Share Posted February 7, 2004 I know what a cross process is but i´m not interested about since i want a positive image. I´d like to know the result from doing: dev+rexposure+dev+fix that´s skipping the bleach but staying in a reversal method. maybe it works, but i´d like to know if anyone tried before thanks Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted February 8, 2004 Premium Member Share Posted February 8, 2004 I believe the bleach is essential in reversing the image into a positive one, by allowing the initial density created by exposure to be removed, leaving the reverse levels of density of silver halide, which is then exposed and redeveloped. So if you skip the bleach step, you never remove the first layer of silver so you end up with a negative image. Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted February 8, 2004 Premium Member Share Posted February 8, 2004 Paraphrasing the Filmmakers Handbook: About reversal processing: The developer converts the exposed silver halide of the latent image into metallic silver. Whereas in negative processing, at this point the unexposed silver halide would be removed by the hypo (fixer) and wash, instead with reversal processing, the metallic silver is removed instead by immersing the film in a bleach, leaving the unexposed silver halides, which are still light sensitive, in the emulsion. The silver halides are exposed to light and then redeveloped again, and fixed in the hypo. So if you skip the bleach step, you will not end up with a "reversed" image -- i.e. it will stay a negative image. Link to comment Share on other sites More sharing options...
Fulgencio Martinez Posted February 8, 2004 Author Share Posted February 8, 2004 Thanks guys, It seems like a bad idea to skip-bleach in reversal. Does anyone know if i can use E6 bleach solution. It seems to be the only bleach sold already mixed. Else i´ll need to play at home with sulfuric acid. should i be scared about this? Link to comment Share on other sites More sharing options...
Mitch Gross Posted February 8, 2004 Share Posted February 8, 2004 George, you want to field this one? Link to comment Share on other sites More sharing options...
Sam Wells Posted February 11, 2004 Share Posted February 11, 2004 What is it you are you trying to achieve ? -Sam Link to comment Share on other sites More sharing options...
Premium Member John Pytlak RIP Posted February 13, 2004 Premium Member Share Posted February 13, 2004 Eliminating the bleach step in a B&W reversal process will leave ALL the silver in the film, in other words, no image --- the film will come out of the process BLACK. :wacko: Here is the process sequence: http://www.kodak.com/US/plugins/acrobat/en...h2415/h2415.pdf http://www.kodak.com/US/plugins/acrobat/en...ssing/H-661.pdf If you are not familiar with safe chemical handling, weighing, and mixing, better and safer to buy the prepackaged chemicals. And read and follow all the safety instructions. Link to comment Share on other sites More sharing options...
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