Here's another good resource about japanning. This person collects woodworking hand tools and has two methods of japanning. The first is very similar to Glenn's method. It's a more a up to date process, using modern paints, etc. (Note that he uses auto engine paint.) The second method is the more traditional way. It concerns me that he actually uses a brush to apply the asphaltum paint. Anyway, it think that it's very informative and right on target with Glenn's advice, so I'm following that Glenn; although, I think I'll try the engine paint for my base coat.
https://home.comcast.net/~rexmill/pl.../japanning.htm
~ Cindy