The inverted acetype process was spawned out of my experiments with the regular acetype process, and the conventional black and white reversal processing procedure.
To begin with, a black and white slide must be made using the standard development sequence which looks something like this:
Detailed instructions can be found on the Ilford pdf sheet found here.
The main difference, and the last remaining step, is to then paint the film chrome or silver, so that the slide becomes an image viewed by reflected light, as with a standard acetype, except that this time it is a silver positive with chrome (or whatever colour you choose to paint) highlights. In effect the inverted acetype process allows us to make positive images that are entirely made up of different shades of silver instead of black and grey.
As with an acetype, a relatively thin image is needed and can be achieved in a number of ways. The first is to overexpose the film by somewhere in the region of 4 to 6 stops. The image below was exposed in steps at 0.75 to 6 iso and developed normally, although at the time it was produced I was still making the same mistake of painting over the emulsion side, instead of behind it.
The problem with overexposing so much is that contrast is greatly reduced, which may not actually be a problem at all depending on how you want your photos to look.
The second method is to expose and develop normally at first, but to carry out the second development by inspection, preferably in a more dilute solution, so that the density can be periodically examined and development stopped before the image becomes too dark.
The third method is to re-bleach the positive after carrying out the entire reversal process, using a dilute bleach that acts very slowly on the remaining silver. Passing the film back and fourth between the bleach and a water bath for inspection should also help minimise loss of density in the darker areas. Each method will produce different results, so it is important to test to see what it right for you in terms of convenience and aesthetic. Combinations of some or even all of the above are possible.