lee said:
thanks Murry for the info
lee\c
Just another word on this. In the 30s and 40s it became common practice to put a super coating of hardened gelatin (*on top of the emulsion layer*) on papers to reduce the risk of stress marks. Since the carbro reaction depends on 100% contact of the bromide printer with the sensitzed carbon tissue the super coating interferes with the process, especially in the highlights, since the tanning action takes place in the hardened super-coating, which is not image area, rather than in the silver image. This results in loss of highlight detail.
When carbro was popular there were several brands of special non super-coated papers available on the market. These papers more or less disappeared in the 50s. The fact that there are now at least two different non super-coated papers on the market should be of interest to anyone seriously thinking of making carbro prints.
Sandy King