I’ve found an exceptional third source for this process which includes all of the ins and outs of making your own emulsion.
http://www.unblinkingeye.com/AAPG/DPlate/dplate.html
It’s based upon a workshop that was given through the Austin Alternative Process Group. Would have loved to attended the workshop!
http://unblinkingeye.com/AAPG/index.html
For what it’s worth, this looks like a great group as well. I was just in Austin over the holiday. Will definitely look them up next time I’m passing through.
Best!