Over-sanding after polyurethane

So I was finishing a pine wood cover for a project, we can just assume its a box for this discussion. I stained it to my satisfaction and then applied the first layer of polyurethane. I have not done this a lot, so YouTube told me to wait 24 hours and sand between poly coats. I used a sanding block at 120 and within a few strokes, the stain started to come off and expose the bare wood in a corner spot. I am in shock that I went though all the poly and stain so rapidly. Do I need to sand down everything and start over, or can I risk applying another coat of stain and see where it fills in? Thanks!

In my experience, it is best to apply at least 2 coats before sanding. Sometimes the first coat gets absorbed into the wood fully. I also wouldn’t sand with anything less than 220 once you get to poly stage. Remember, all you’re trying to do is get the finish flat and smooth. Also, humidity and temperature can play a big role in the wait time.

As for the repair, I would touch up the stain, then re poly the entire surface and start from there.


Seconded on 220 being the biggest to use at this point. I tend to go for 400, and use a very gentle touch.


Touching up the stain is extremely unlikely to make things worse, so you might as well try it and see how it looks. Worst-case you’d just have sand and re-finish like you were going to anyway.

I would expect a touchup to look just fine, but sometimes things take stain weirdly.

I almost always sand with >=220 after the first coat, but I usually use water-based poly that raises the grain a bit more than solvent finishes. Gentle touch is definitely what you’re going for.

Thanks for the replies. I’ll try to touch up the stain and see how that goes. No more 120 thats for sure!