I have had good success by applying black dope first, usually a
couple of coats are needed. Then apply epoxy thinned with denatured alcohol (available at Lowe's, Home Depot, etc).
I usually thin with about 1/4 alcohol and 3/4 epoxy. Be sure and
mix the epoxy thoroughly before thinning with the alcohol.
I found it sets quicker if you do. Note: if you are using thin epoxy,
you may want to add less alcohol. I look for a consistency like
clear dope out of the bottle. Good luck!