As promised, here are the results of the CPES vs. Urethane denting tests. The purpose of this test was to find out which one would dent the most and if I should sand the Urethane off my trim and recoat with CPES followed by new coatings of Urethane.
I cut three one foot pieces of trim board and sanded each. One was coated twice with CPES; one, twice with Spar Urethane; and one, twice with CPES followed by two coats of Spar Urethane. Each was given at least 4 hours between coatings and a final cure time of more than 48 hours. The one with both CPES and Urethane on it was given 24 hours between the CPES and the Urethane coatings.
First, I tried a pressure test. I laid them, equally spaced out on a weighing scale and applied the edge of a metal ruler to them, pressing on either side of the middle board, until the scale read 50 pounds.
Nothing happened! So, I tried 60 pounds and still couldn’t get as much as a whisper of a dent out of any of them!
Okay, on to the dreaded can test! Fearing this one could get messy (I was using a can of condensed milk), I took it outside:
I tested each board individually, rolling the can off or slipping the can off on its head from a height of 2 feet. I was able to get dents in all of the sticks this way.
Next, I put all the sticks together and compared the dents visually and by touch:
My conclusion? It made no difference. They all dented equally; so, I won’t be refinishing my trim to add CPES underneath the Urethane.