You can pick the perfect finish and still end up with a top that peels or feels rough to the touch. Nine times out of ten, that comes down to sanding and prep. Part 3 covers how far to sand, why going too fine causes problems, and the between-coat routine we use in our shop for a finish that feels as good as it looks.
The M2 Finishing Guide
- Film vs. Penetrating Wood Finishes
- Oil Finishes and Hard Wax Oils
- How to Sand for a Smooth Finish (you are here)
- How to Apply Wood Finish
It Has to Feel Smooth
Think about what happens when someone sees a nice piece of furniture: the very next thing they do is walk up and touch it. If the surface feels rough or textured, it doesn't matter how good it looks. A tabletop isn't a grippy stair tread. It doesn't have to be glossy, but it should feel smooth with a soft touch.
One thing I tell everyone who finishes in our shop: how it feels is just as important as how it looks. Everything in this post is about getting there without sacrificing protection.
Why Film Finishes Peel
When a film finish fails, it usually doesn't wear out; it peels. In most cases we've seen, that comes down to surface prep:
- Contamination. Oils, waxes, silicone and grime keep the finish from grabbing the wood. Make sure the surface is clean before you start.
- Sanding too fine. This is the big one, and it surprises a lot of people.
How Far to Sand Before You Finish
For film finishes: stop at 150 to 220 grit
A film finish (poly, lacquer, varnish, oil-based or water-based) doesn't soak into the wood. It lies on top. That first coat needs to soak in just a little to get a good grip. If you sand all the way to 600 grit, you've polished and burnished the surface glassy smooth, and there's almost nothing for the finish to hold onto. It will cure and harden, but its bond to the wood is weak, and down the road it can peel right off.
Our rule in the shop:
- 150 grit is where we usually stop when building furniture.
- 220 grit is the most we'd ever recommend before a film finish.
- If you're staining, going to 220 helps close up the pores a bit for more even color.
For oil and penetrating finishes: you can go finer
Penetrating finishes don't need to bond to the surface as a layer, so you can sand up to 600 grit before applying an oil or hard wax oil. They also don't raise the grain much, so they feel smooth after the very first coat. That's a big part of why people love them. The tradeoff is protection, which we cover in Part 1.
The Rough First Coat (and Why That's Okay)
Here's what throws people off with film finishes. Because you stopped sanding at 150 or 220, your first coat is going to feel rough. The liquid raises the grain, then hardens with those raised fibers locked in place. That's normal, and that's okay. It's exactly what the next step is for.
Sanding Between Coats
Every finish tells you to sand between coats, and this is why. Once the first coat is dry, sand it with a finer grit, around 400. It may feel like you're sanding the finish right back off, but you're not. You're knocking down the raised grain that's now stiffened with finish, leaving a smooth base.
You can almost do this with your eyes closed. Run your hand across the surface and feel for rough spots. If it feels rough, sand it.
Wait, didn't we say not to sand past 220?
That rule is for bare wood. Now there's a layer of finish on it. When you apply the next coat within the recoat window listed on the can, it bonds to the coat underneath, finish to finish, which is a much stronger bond than finish to bare wood. So now you can sand at 400 or even 600 grit for a smooth surface without risking adhesion.
Clean Off Every Bit of Dust
Before the next coat, get all of that sanding powder and dust off the surface. Vacuum it, blow it off with compressed air if you have it, then wipe it down with a tack cloth or a clean, lint-free microfiber cloth. Any dust left behind gets locked into the next coat and shows up as bumps you'll feel with your hand.
How Many Coats?
The second coat goes on and dries much smoother. With a good finish laid at the right thickness, two coats can be enough, but we usually end up doing about three. That gives us enough thickness for solid protection and a surface that feels great.
Don't Forget the Edges
This is one of the most commonly overlooked steps. Finish is naturally thinner on the edges and corners of a tabletop, so the edges usually feel rougher than the top. Picture sitting down at a table where the top feels perfect but the edge right in front of you feels rough. Check your edges every time, and don't be surprised if they need extra sanding or an extra coat. They're just as important as the tabletop.
The Takeaway
- Keep the surface clean, and stop at 150–220 grit on bare wood before a film finish so the first coat can grab.
- Oil and hard wax finishes can go up to 600 grit.
- Expect a rough first coat. Sand between coats with around 400 grit and recoat within the window on the can.
- Remove all the dust before every coat.
- Plan on two to three coats, and always check the edges.
Next up, Part 4: How to Apply Wood Finish: Wipe, Brush, Roll or Spray
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