Hi Again:
Just a couple of more things I should have mentioned that are helpful to us. After we "paint" the cork roadbed with the white glue and before we apply any ballast it is imperative to make sure there is no glue on top of the track ties. Wipe them clean. If you don't, after you have applied the ballast and try to clean the ballast from the top of the ties, you will have a gooey mess.
Next, when applying the ballast, some of it will inevitably roll down the side of the cork and never be in a nice straight line along the base. We used to use a small paint brush to pull it back in place but have since found that the new "foam" paint brushes, the ones with a piece of foam cut to a sharp "V", work even better. Use one that is about 1" to 1 1/2" wide. It really works well in drawing the ballast back in place and helping form a nice contour with the cork board.
Dwight77