The silver content of albumin and silver halide in gelatin is judged and adjusted in a different manner in each case.

In the Kahn formula, when coated by the dip method as in albumen, the content of silver cannot be judged or adjusted. When coated in a normal manufacturing process, it can be.

Therefore, to coat the Kahn formula, you have basically 2 options. You use a brush or you use a coating blade. In either case, the goal is to spread about 12 ml of the emulsion over each square foot of paper. This works out to about 500 mg of silver in each sheet of 8x10 paper. With a brush this may require from 1 - 3 applications, and with a blade it requires a gap of 0.005".

This is silver rich, but that is an artifact of early emulsions. Only a small part of the silver was used in the imaging. The rest was washed out in the fix.

In addition, the old emulsions were rather low in gelatin wrt silver but high in overall amount per square foot.

The overall combination gave old prints a rather velvety look, especially on the old baryta papers or untreated papers which had less surface repellancy.

PE