Ken61, and others,
Thank you for your interest in this subject, I am a little disappointed that this thread has not taken off as you maybe would expect amongst enthusiasts.
When you consider that the task is labour intensive and many of us have time to spare and for free, why do not more of us learn this soon to be lost skill?
I do not think there is one book or article has ever been published with a step by step guide to barrel blacking or browning. All we ever read about is take care with problems , but none or few solutions to those problems.