The technique consisted of creating a mould by exposing to light a photograph of the image covered with gelatine bichromate.

The three negatives were then printed on thin sheets of bichromated gelatin containing carbon pigments of red, blue, and yellow, the complementary colors of the negatives.

In 1872, his son adapted the process to the handling of photographic images (a), produced either by using asphalt or by use of bichromate gelatine on a zinc reserve base.