[alt-photo] Multi coat Gum -3rd+ coats tends to wash off

[pfriedrichsen at sympatico.ca]

Has anyone experienced the following problem?

When doing three or more separate coats of gum, I find that the third 
(and all subsequent)coats have a tendency to wash off. The wash off 
occurs only where the previous undercoats remain. In areas where the 
paper remains uncoated (highlights), the top coat will anchor. I am 
guessing that the fibers, voids, etc are being filled in and the top 
coat has little left to anchor to.

There must be something that I do not have right but am unsure of 
what that might be. When I tested the individual coats on clean 
paper, they adhere well and do not flake or wash off and produce an 
image with good scale.

Any ideas?

Peter Friedrichsen