Been trying the carbon process as per the Bostick & Sullivan PDF. The most pressing issue is fog - I can't get a totally white white. I'm guessing the most likely cause is the sensitizer - potassium dichromate. I mixed a batch of 3% and dilute it down to 1% on a print by print basis - but at 1% I need a really contrasty negative. I made 1 litre but after the first week it's turned more of a coffee colour rather the the fresh "cherry" colour when I first made it - stored in the dark, but room temperature - 72 - 75F. I originally was storing in the refrigerator but it seemed to precipitate out. In any event I'm going to make a fresh batch @ 2% and see if that helps - certainly the first couple of prints I made had less fog than recent ones. Any other ideas? Thanks.