Here is my formula calculator:

http://www.apug.org/forums/forum37/1...alculator.html

Let me know if any further clarification is necessary. If you have trouble pinning the values, use the Goal Seek functionality in Excel, and do it in the order: p-Aminophenol - sulphite - hydroxide. The target value must be 1 (or 100%) in each case. It takes me about twenty seconds to find the quantities for any combination of feed materials and any volume. If you are stuck, PM me and I'll work it out for you.

This thread provides some additional insight and examples.

http://www.apug.org/forums/forum37/1...e-insight.html

The formula as above is in use in all its permutations, and all of them work consistently and reliably. I suggest you try to obtain pharmaceutical grade raw paracetamol. You may resort to Tylenol capsules (or whatever your local brand name is - here it is Panado), but they contain additional materials (nano silica??), probably to improve the flow properties of the bulk material, which is very light/fluffy and gets airborne by the slightest breeze. It sticks to static surfaces with a tenacity that is hard to describe. To work with pure paracetamol is almost like herding cats. But in larger quantities it is cheaper and once dissolved, is easy to work with and provides a much clearer product. I have paid ZAR210 for 2kg. That translates to roughly US$11.50 per kg. That quantity makes a lot more than five liters of Rodinal concentrate, and one uses on average about 10 ml per film. Some go to 4 ml per film for 1:100 stand development.