I have a wood kitchen table I just purchased. The salesperson recommended sealing the wood with polyurethane as the table did not come with this seal. (It's a rustic looking table)

I used oil-based polyurethane on the first coat. It's now dry (it's been 4 days) and I need to sand that coat. I started sanding with 220 grit sandpaper and it looked like it was scratching the wood, not sanding the polyurethane. Meaning if I wipe away the dust from the sanded polyurethane, I will still see scratches and not a smooth surface.

I've seen various recommendations on the internet:

1) Use a higher grit sandpaper than 220.
2) Add another layer of polyurethane without sanding.
3) The scratches will disappear when the next layer of polyurethane goes on.

I'm scared to proceed sanding the whole thing down because I don't want to potentially ruin the stain. Curious what good wood-working folks would do.

(As for doing the seal I have kids and am pretty sure they would ruin this table if it's not sealed in some form or fashion)


Here is a picture. Looking at this now I wonder if I just went against the grain?

I feel like polyurethane application is a huge rabbit hole with many different opinions, but also a huge range of contributing factors:

Questions I'd be asking:

• What sheen of poly (gloss, semi-gloss, satin)? - The flatter the sheen, the more diligent you need to be with continuing to stir because of the suspended solids. Like stirring for 10 whole minutes before you start, and stirring periodically during application. Don't shake.
• What type of environmental conditions (humidity/temperature)? - The warmer and dryer, the faster the poly will cure which affects time between coats.
• What method (Brushing, wiping, spraying)? I've done all of them. I've grown to prefer wiping, but it takes more coats and needs to be thinned with solvent. I just found it to be more forgiving for bubbles and easier to coat items with both vertical and horizontal surfaces. If really complex, I'll probably consider spraying.
• How many coats? I've done a few table tops at 5 coats. There were multiple layers I didn't sand in between with good success. Thin layers are a must. Do not try to apply thick coats.
• How well are you controlling dust? You need to be extra diligent with keeping the area from stirring up dust, otherwise you'll be dealing with a lot of bubbles and bumps. Less dust = less sanding.

As mentioned above - you need to sand (and apply your poly) with the grain. I think people sand too hard in general. Sandpaper should do all the work. So when using 220 grit, don't force it into the piece. Basically "wipe" the piece with sandpaper, like you would a with dust-rag, and you don't need to wipe the piece in multiple passes. You're just knocking down the peaks. In my experience, I never sand that first layer of poly. There are so many pores in the wood that the poly soaks in pretty well, so there's not a thick layer on the surface and it still has a lot of surface irregularities.

I also think you should avoid waiting four days between coats. The bottom coat needs to be in a curing phase to form a good bond to the next layer. It still needs to be "dry", but that's not the same thing as cured. Where I am located it's very dry and I have good success with 2-3 layers of poly in a day. I don't think that's true in a more humid environment.

If I was in your shoes, I would try a very light sanding with the grain when you have scratches that cross the grain, but be watchful if it starts to take the stain off. I would put two very thin layers of poly, one within 24 hours of the next one. Then I might try a light sanding. Then repeat with a couple layers of poly, and final light sanding.

You might get 6 answers if you ask 5 different people, and all of them may have some validity, but that's my two cents.

Use a sanding block and very LIGHTLY sand with the grain with no coarser than 320 grit after the first coat. Water based poly is much easier to work and dries a lot faster. Multiple coats in a day.

Sanding block 400 grit worked like I hoped. Luckily the scratches are isolated to one small spot so it's recoverable. Stupid me for using a circle motion at first.