I made some dry plate glass negatives once with Rollei Black Magic (RBM) emulsion. See:

RBM is available in 3 different emulsions, two graded and onevariable contrast emulsion. There is also gelatine, etc. from Black Magic for coating undergrouds, etc.
Tech info & How To, click here (also about how to modify gradation, ...).

Among others, also available at macodirect.de

What type of Safelight is suitable:
* RBM23: red or yellow green
* RBM33: red or light brown, no yellow green

I hope this helps ...