Applying finish to wood should ideally be the last step of your project. But there’s a chance that the grain fibers might swell even after you apply your finish. That as a result, ruins its overall look and texture.
To prevent wood grain from raising, you have to raise the grain ahead of applying a coat of your finish. By raising the grain before, you can knock it down by sanding it lightly and then apply your finish. By following this technique you get an even layer of finish throughout and no grain raise whatsoever. One more way is to avoid using a water-based finish and use oils instead.
These days water-based finishes are pretty common and very much preferred by woodworkers. People love using polyurethane and stains with a water medium. They are much more convenient compared to oil finishes. But this convenience comes with its downsides in the form of raised grain.
Though it is nothing too big that you would avoid using water-based finishes altogether. There are multiple ways to prevent wood grain from raising that we will discuss throughout this article.
So let’s dive straight into it!
Preventing and Fixing Wood Grain Raising
The best way to completely avoid wood grain from raising is to use oil-based finishes instead of water-based ones. Oil, when absorbed by the wood does not raise grain, instead, it strengthens it. It replenishes the natural oils in the wood that have dried off with time. It also deepens the color of the wood, bringing out the natural beauty of its grain.
But the downside to that is it takes a long time to dry and cure. The time varies from 24-36 hours for the oil to fully dry off. If you don’t wait that long, you can feel the stickiness of the oil on the wood. That is because it has not absorbed the oil fully yet. Once the wood is completely saturated, it will leave droplets of oil on the surface. Just wipe them off and you are good to go.
However, this can be a major inconvenience for people who cannot wait that long. Water-based finishes offer you much better convenience as they dry about an hour later. Also, you might want to apply stain to the wood instead of the oil to darken its color.
But water-based stains and finishes will raise wood grain, so how to prevent that from happening?
Raising Wood Grain Ahead of Applying Finish
One surefire way of ensuring that water-based finishes do not affect your wood grain’s texture is to raise it before applying them. You can knock down the raised fibers with a light touch of high grit sandpaper. And then apply your water-based finish for much better results.
So first you need to prepare your wood for applying the finish. You sand the surface all the way up to 220 grits. With the wood smooth to the touch, you take a small foam and apply a coat of water to the wood. The quantity of the water you apply has to be equivalent to that of the finish you will apply. It can be slightly more or less but don’t completely soak it in water.
Once that is done, wait overnight or at least a few hours to let the wood absorb that layer of water. Now inspect closely, some fibers of the wood grain have popped up even though you sanded it down to smoothness before. You now need to knock it down again. To do so take high grit sandpaper and lightly rub it over the surface.
The reason for using high grit sandpaper is so you don’t break new fibers. You just need to get rid of the grain fibers that have raised due to the water absorption. If you break into the grain and new fibers, they will swell again when applying your water-based finish.
Lightly sand off the surface, just enough to remove the raised grain. Now touch it and see if it is even and now you can apply your water-based finish. Since the grain has already been raised before, it will not happen again.
What is the Reason Behind Wood Grain Raising?
Wood is what you call hygroscopic and its structure is very much like a sponge. And because it is just like a sponge it absorbs water into its pores.
Usually wood has two types of water content, one is the cell water, which is trapped inside the cell walls. Once that water dries off, it cannot be replenished, so this part is less important.
The second type of water content is in its porous structure, and that makes up most of its water weight. And so when the wood is dried after being freshly cut, it loses most of its weight because it loses the water outside the cell walls. But when the wood is again exposed to water it can absorb it and store it in that porous structure.
When you expose the wood to water again after it has dried, the wood expands as the water is stored inside the porous structure of the wood. Whenever the wood expands because of moisture absorption, the soft cells push the grain fibers up. This is what causes the raised grain in wood once you apply water-based finishes to it.
If you use wood that is dense and has pores that are either blocked off or the pores are too tight, it will not absorb a lot of water. White Oak is one of the best examples of such wood that is water-resistant thanks to its pores being blocked naturally. This is why white oak is the preferred wood of choice for outdoor furniture, wooden boats, and ships.
Sanding the Raised Grain
One way to get rid of the raised grain is to sand it down. The first thought everyone will have when sanding it would be to smoothen it down again. Though you should avoid sanding the piece too much just to knock down the raised grain. You just need to touch it lightly with sandpaper and get rid of the raised fibers only.
If you sand it in too deep, new fibers will spring out if they are exposed to moisture again. That is because you cut into fresh grain when sanding too much. So just sand it with a light touch and it should go back down without breaking the new fibers.
Also, another way to make sure you don’t overdo the sanding is to use high grit sandpaper. Usually, we advise people to not sand their pieces above 220 grits. That is because if you sand your piece too finely it will not accept the finish as good. But for this task use high grit sandpaper of 400 grits or more. Just lightly give it a rub and the fibers will get knocked down.
If you have applied a finish like polyurethane already then it is all the more important that you don’t end up sanding the finish off. Lightly sand between layers to knock down the raised grain and you will end up with a smooth and amazing finish.
The Grain Is Up and Nothing Helps, What Now?
If the wood grain has raised and nothing you do is working, then the only option is to choose the right finish. A finish that will not only take well to the raised grain but also look good even though the surface is not completely smooth.
In our case, we have found staining responds well to raised grain. It looks better than most other finishes in this situation.
FAQ – Frequently Asked Questions
Does oil cause raised grain in wood?
By avoiding water-based finishes altogether, you can ensure that there is no raised grain in the wood. Using oil-based finishes is the best in this situation as it expands wood as water does. Oils are generally a great finish to apply to the wood and enhance the beauty of the grain structure. Just be ready to give it the time it requires to cure and dry properly.
Why can’t you sand down the raised grain if it springs back after applying finish?
You can sand down the raised grain if you have used polyurethane. A light rubbing down with high grit sandpaper will knock down the raised fibers. But if you have applied a water-based stain, you can’t really sand it lightly either. Although it will knock the fibers that have popped out after the grain has absorbed water, it might also remove a little stain as well.
You can’t apply another layer of finish as it will darken the whole thing and might even create an uneven look. The best way to deal with it is to raise the wood grain and knock it down before applying the stain. Since the fibers that popped out because of the water have already been shaved off, the wood will remain smooth even after staining it.
What wood is best for preventing raised grain?
Non-porous woods are the best choice if you want to prevent wood grain from raising. Since the pores are either too tight or blocked off, the wood will not absorb water that well. So you are better off buying hardwoods if you are concerned about this problem.
What happens if you use low grit sandpaper to knock down the raised grain?
If you use more abrasive or coarse grit sandpaper to knock down raised grain, it might cut into fresh wood. If you break into the fresh grain it will swell up again when it comes into contact with water. To avoid that you have to use higher grit sandpaper like 400-500 grits. Also if you are sanding over a finish then you need to be extra careful as you might end up sanding it off.
Final Thoughts
If you are going through trouble with raised wood grain, then hopefully this article answers how you can prevent and fix it. If this has happened to you for the first time, don’t be afraid, you can always make it work. After all, woodworking is about experimenting and going through new experiences. Just make sure you follow the steps mentioned in this article properly, and you are good to go.
