Hey guys wanted to get some input on a project I’m doing. This question is really for the experienced guys but any help is better than none. Here goes, my brother wanted me to epoxy an old wood wash tub that he got at an auction. He’s making it into a sink for his cabin he owns. I’ve layed two coats of epoxy 2000 from Surf Source on it so far, sanding in between the coats. I planned on putting a third on and got to thinking about if I could put it on without sanding again. Now I know from reading here on Sways that people have warned about problems when you don’t sand in between coats. But I’ve been told by an experienced epoxy guy that you don’t always have to sand in between coats. He told me that I could just rub down with denatured alcohol and coat away. Now I’m not sure if this only pertains to specific types of epoxy or just maybe a little secret. Or maybe it depends on what you’re putting epoxy on? I’m not a guy to cut corners or to not listen to experience but was very curious about this subject. I have little experience with epoxy, only glassed 7 SUP’s with it so far. The reason I brought this up is because this experienced epoxy friend happens to be my Battalion Chief. At his fire station they made a dining table of wood with a fire emblem and two axes inlayed in it. He used clear epoxy to coat the table and never once sanded in between coats, 8 so far. Thats when I questioned him about not sanding and thats when I got the “no sand needed” answer. My problem with the tub I’m doing is that I can only put thin coats on the tub due to the slope of the bowl. If I put too much on at once, it just runs down to the center. I have to baby sit it and keep running the brush around till it sets enough to not run which is a pain. These thin coats become a little thinner when I hand sand. Not much as I’m only scuffing it to get the shiny out and smooth a bit. But if there’s a way to just skip right to the 3rd coat without sanding, I’m all for it. Any tips, info, or plain ole “DON’T DO IT” would be great.
The issue is chemical vs. mechanical bonding – affected by time between coats.
If the epoxy has cured between coats, your bond strength is dependent on mechanical bonding (sanding).
For what its worth. Before and after first coat.
If compltely dry, must sand.
If you wait till still tacky, apply another coat.
I’d sand it.
Better safe than “SHIIIIIIIIIIITTTTTTTTTTT”!
+1 for Stoneburners comment.
I’d use the "thin layer work time’ in the product spec sheet as a guide, and apply the next coat just after the first coat has become a little too stiff for brush application. That way you get a primary bond (chemical bond). The more it has set, the more you need to introduce many microscopic tounge and groove situations to achive an interference bond.
I think that rubbing an incompletely cured epoxy with alcohol might soften the surface so much that the cloth introduces enough scratches in the surface. This might be 'sanding by other means". It would be interesting to compare microscope pictures of both methods.
Rather than learning on a finished product, you might think about trying all the different ideas on some scrap
Thanks for the help guys I ended up just sanding away like you stated. First and second coats were a few days apart so definitely didnt want to mess it up by doing a test like a idiot. Definitely want to do some test though with different ways with epoxy in future.