I have a project that is chestnut and epoxy.
I want to sand for an oil polyurethane finish.
I read that to poly on epoxy they say 400-600. ( these are some grit ranges I hear from my research )
But wood they say ( 180 - 220 )
So this makes me think
Do I have to meet in the middle, stay low or can I go to high on the grit ? (I’m thinking about adhesion )
I don’t think you should have any issues with adhesion, as long as the epoxy is clean and dry. I find using denatured alcohol works well for this purpose.
I would still take it to at least 600 grit, if not 800-1000. I don’t think epoxy is very forgiving when it comes to showing sanding marks or scratches. If you want a super glossy finish, like the epoxy looks right after pouring/drying, I have had the best results with automotive 2K clear coat out of an airbrush. Even car wax and a buffer wheel was still too dull looking. Also, using this automotive clear coat, I have only needed to sand up to 600 because the clear coat fills in most if not all of the small scratches. I posted about using this here: https://forum.onefinitycnc.com/t/anyone-had-experience-wet-sanding-to-poloshing-epoxy/16777/2
Thanks for the help this puts me at ease. Luckily the epoxy is died rich purple so scratches are hidden by the orbital quite well (unlike a clear pour) even at 180 grit
but I had no round discs for 220 so I went in by hand dry . Looked like a cat had been on it. Goes to show how good random orbit sanders are. I have some disks that will take me much higher on the way.
So it should be pretty sweet by the time I’m there on the grit. Hopefully the poly will bring it back to life 2
I’ll put a before and after in here with the steps I took. Won’t go crazy it’s not a paid job.
Chestnut natural and epoxy currently at 180 grit no poly (obvs) . Shell from vectric clipart.
400 grit 50percent poly 50 percent white spirit