Well, I've searched the web for alternatives, but most sites still give the old bleach formula that uses sulphuric acid and potassium dichromate. Here is another such:(posted 8860 days ago)ILFORD TECHNICAL DATA - REVERSAL PROCESSING OF ILFORD NEGATIVE FILM Reversal processing enables black and white transparencies to be produced directly from ordinary negative materials exposed in camera the normal way. The basic reversal process starts with development of the negative image. At this point the used silver halide is not fixed out as in normal film processing, but completely bleached away, using an acid bleach (see warning). This leaves the remaining silver halide ready to be light-fogged and then re-developed to form the final positive image. Between the various stages of the process, washes are used to prevent contamination of each new processing solution by the previous one. There is only one critical stage in reversal processing; the first development. The first negative image must "use up" just the right proportion of the emulsion, so as to leave behind the correct amount of silver halide to give the desired positive image at the end of the processing sequence.
RECOMMENDED FILMS The suitability of a negative film for reversal processing depends largely on its inherent contrast. Little can be done to change the contrast appreciably by changes in processing. So choose a film for reversal processing according to the ultimate contrast required in the final positive image. For this reason FP4/FP4 Plus is recommended for a moderately soft graduation image with pleasing tones. PAN F gives somewhat higher contrast and pleasingly bright positives. Particularly suitable for copy slides of photographs. We do not recommend reversing high speed films, as they are likely to be too low in contrast.
REVERSAL PROCESSING PROCEDURES These are two methods available to make transparencies from black and white films. These are Kodak's T-Max 100 Direct Positive Film Developing Outfit and a user prepared procedure. Each has its own unique quality, but work on the same principals. Black and white reversal processing involves six main stages: 1. First development - here the exposed image is developed to a negative. 2. Bleaching - here the negative image is completely bleached away. 3. Clearing - this is to clear away all traces of the powerful bleaching bath, and the slight stain it leaves behind. 4. Re-exposure - this is a total fogging exposure to make the remaining silver halide readily developable. 5. Second development - all the residual silver halide is developed fully, to form the positive image. 6. Final fixing - this is an optional stage which removes any last traces of silver halide that did not develop and leaves the image clean and fully transparent in the clear parts.7. Final washing and drying are quite normal. T-MAX 100 DIRECT POSITIVE FILM DEVELOPING OUTFIT When using this kit, we would recommend the following exposure modifications coupled with the corresponding development times. The times are given for first development and are a GUIDE ONLY. Modification may be needed depending on the output required.
FILM EXPOSURE (STOPS) FIRST DEVELOPMENT TIME PAN F +1 3 minutes FP4 Plus +1 6 minutes 400 DELTA* +2 6 minutes *May produce transparencies of low contrast. USER PREPARED REVERSAL PROCESSING PROCEDURE - SOLUTIONS REQUIRED A. Developer - Use either ILFORD Bromophen 1+1 with water or ILFORD Universal Paper Developer diluted 1+15 with water. To one liter of the working strength developer add Sodium Thiosulphate crystals (hypo) in the following proportion: PAN F 8g FP4/FP4 Plus 12g B. Bleach - Mix the following solution: Potassium Dichromate 10g, water 1 liter; when dissolved add, slowly and carefully, 10ml of Sulfuric Acid (concentrate). As you pour in the acid to the dichromate solution, much heat will be generated, so pour in the acid very slowly and carefully.
IF IN DOUBT, ASK A QUALIFIED CHEMIST TO MIX THIS FOR YOU. Protect your skin and eyes by using rubber gloves and protective eye wear. ********************************************************************** WARNING!! Concentrated Sulfuric Acid is DANGEROUS and HIGHLY CORROSIVE!! ALWAYS pour the acid into the water, and NEVER the water into the acid! KEEP OUT OF THE REACH OF CHILDREN!!! CAUSES severe burns. May be fatal if swallowed. DO NOT get into eyes or onto skin or clothing. Keep out of the reach of children. In case of contact: EXTERNAL: IMMEDIATELY flush with tap water, then water containing sodium bicarbonate. INTERNAL: DO NOT give an emetic. Give whites of eggs beaten with tap water, milk of magnesia or milk. GET MEDICAL ATTENTION AT ONCE
C. Clearing solution - Sodium Sulphite (anhy) 50g. Water to 1000ml. D. Second Developer - It is most exonomical to re-use the first developer over again. This is not ideal because of the added (but unwanted here) solvent. Ideally you would used the same developer, but without the added Hypo. E. Final Fix - Universal Fixer 1+9 or any other available fixer. THE REVERSAL PROCESS SEQUENCE 1. First development 12 minutes 2. Wash 5 min., perferably running water 3. Bleach 5 minutes 4. Rinse 1 minute 5. Clear 2 minutes 6. Rinse 30 seconds 7. Second exposure 30-60 sec to white light 8. Second development 6 minutes 9. Rinse 30 seconds 10. Fix 1 minute 11. Final wash 10 minutes 12. Dry This file was made available through the courtesy of Ilford Corp.