I have a project that is made of Black Walnut and is about 7"x10". A small area of the surface has an epoxy ovel about 3"x1.75" and about 0.200 deep cut in it. I like the finish that I get using a gloss urethane from a spray can from Lowe’s on the walnut. I have found that the urethane provides a clear finish for the epoxy as well, reducing the amount of work required to finish the epoxy. What is anyone’s thought if urethane will be OK over time on top of the epoxy? I don’t want it to peel.
Cosmetically I have not had good luck with spray water based urethane over black cast acrylic.
The surface quality was no comparison to the original acrylic.
I use wipe (oil) based polyurethane over epoxy with no problems. After sanding a project with epoxy the epoxy looks dull as dish water but a few coats of wipe on poly and it shines up quite well. No need for a bunch of buffing the epoxy prior to the application of wipe on poly. Now water based may be a different story. Water based products tend to bead up over plastic and epoxy is essentially plastic. A water based sealer might help and the sealer would give some tooth for the topcoat of water based poly to adhere to. Unless there is a specific reason I would use oil based polyurethane over epoxy. Water based has less VOC but after both oil and water based polyurethane cures fully they are both food safe. As far as food safe I mean the poly touching food it is safe but polyurethane should not be used anywhere it will be cut because it can flake off and personally I would not like to eat polyurethane. But if the object is a toy a small child is subject to chew on it so I would not use any polyurethane on a toy of a child under about 10 years old. Older children generally do not chew on their toys like a small todler might.
Thank you for your reply James. I had not realized that the Minwax Urethane that I was using was water based. My big concern is that over time it will separate from the epoxy. Below Guy offers input about an oil-based polyurethane, where he has had good experiences using it over epoxy.
Guy -
I found this oil-based poly on Amazon. Is this what you are using?
You mention “wipe”. Are you spraying the poly on and then wiping it with a rag?
I use wipe on but the spray would work. I like satin but that isy personal preference. Gloss shows every imperfection and scuffs.
The reason I use wipe on is it does not get over spray. For me it is easier to control and on complicated cravings I use an acid brush to get inside things. As long as you control over spray spraying works. Spray poly dries to the touch faster but all poly takes a week or more to fully cure.