I understand the concept and pratical use of unsharp masking but, I'm curious, can anything actually be gained with this technique in a contact print? I've never heard of contact printers use this technique. Are there any? Is it worth the undertaking?
Unsharp masking in contact printing does have one benefit. That would be to reduce negative contrast in the event that a negative had been developed to an excessive density range.
Some time ago a member had sent me an 8X10 negative that had been developed to a DR of 1.90 (as I recall). I made an unsharp contrast reduction mask of .45 peak density. When these two films are printed in register this will bring the effective density range of the negative down to 1.45.
In this case this would allow the negative to print on Azo grade two where before masking it would not have printed because of the excessive contrast.
A second generation unsharp mask could also be used to increase total negative contrast if that were desired. The benefits of increased local contrast and increased perceived sharpness from unsharp masking are limited to negatives used in making enlarged prints.