Measure small amounts of raw chemicals for revesal processing

[Hans Borjes]

I would like to create bleach and clearing bath from raw chemicals. According to what I can read on the web it will not be possible to store the bleach for a sufficient time.

So, in real life I would create stock solution for the bleach and discard it anyway before fully used.

Does anyone make bleach as a single shot working solution from potassium permanganate powder? Given the amount of powder for 1 litre stock solution I had to measure about 250mg for one film.

Any practical approach to handle that would be helpful, e.g. measuring powder in ml.

 

[eumenius]

Hans,
my own experience tells me that it's a good idea to make two stock solutions for your bleach - one with permanganate (dichromate in my case), one with acid. They keep well, and you can make them, for example, 10X concentrated. That means that to get 1 liter of working solution, you take 1 part (100 ml) of permanganate solution, add 1 part of acid stock, and 8 parts of water. After using it, you simply discard it, and make a fresh one from stock solutions each time. The relatively large amounts of chemistry to make stocks eliminate the need in weighing out the small quantities, and it's very convenient to measure out stocks.

 

[eumenius]

Oh, I found out that even the Ilford reversal datasheet recommends making stock solutions of acid and permanganate - just take their formula, and it should be OK.

Regards, Zhenya

 

[Donald Qualls]

A scale made for reloading cartridges (for guns) is generally capable of measuring down to about 6 mg on the divisions (0.1 grain, at 15.4 grains per gram -- powder charges being almost universally quoted in grains for historical reasons). These can be had in perfectly usable form for under $25. A 250 mg quantity of permanganate should be easy for such a scale; I used to routinely weigh charges of 2.7 grains that had to be within 0.1 grain of correct with mine.