I have a jar sitting next to me: "Kodak Abrasive Reducer" cat. 146 4395
It is a small 30 gram container, basically a brown paste that you rub
on the emulsion side of the negative where it scours off thin layers of
the image. Sort of like rubbing compound. Since you control the amount
of reduction by pressure and how long you buff an area, you have a
lot of control.
Many years ago a student turned me on to it. He was doing some amazing
things to his negatives, bascially distressing them in various ways.
Where he worked with the abrasive reducer, the effects ranged from
subtle tonal changes to very interesting black holes.
A few years later I noticed that he was working with dye transfer
matrix film and doing the same thing. The effect of changing the
density on one layer of color only was remarkable.
Carson
carson@ileaf.com