Even we woodworking hobbyists want our projects to have a professional look when we’re done. We want the corners to be square; we want the tables to be level; we want the finish to be even and blotch-free; and we want a smooth surface.
All of this requires work, but since it’s work, we love, we don’t mind. We measure carefully, we assemble well, and we prep the wood the way it should be prepped for the finish we have chosen, whether paint or stain. Part of that prep is sanding the wood surface to make it smooth.
We sand before we begin the finishing process with the first coat of stain, working our way up the ladder to the highest grit sandpaper we believe the wood needs.
At that stage of our project, several questions must be answered, and the answers depend on the first coat of stain applied. We devoted an article recently to addressing a blotchy stain application and how to fix it. The next question to be addressed is whether we should or need to sand after the first or subsequent coat of stain.
Wood Stains and Their Purpose
We know that wood stains add color to the wood. They are like a type of paint we use to add that color and enhance the appearance of the wood grain. They are composed of a colorant (a pigment) and the medium in which it is dissolved or suspended, along with resins and additives.
That medium, usually referred to as a “vehicle” or “volatile”, will be either water or oil, and each has its place and appeal in the woodworking shop.
While paint will simply lie on the surface of the wood, as will gel stains which we will get to later, a liquid stain will actually penetrate the wood and be absorbed into it. Staining the wood will seal the pores, and although the wood will not be made waterproof, staining it adds water resistance.
Wood stains have 4 primary ingredients, as we noted: a pigment, a volatile, resins, and additives. The volatile will evaporate as the stain dries, leaving just the pigment, resin, and additives on and in the wood.
With the consistency of thin oil or water-based paint, stains are easy to apply either with a brush (bristle or foam brush) or a cloth (for the liquid stains); gel stains need to be brushed on, and a foam brush will work just fine.
All excess stain not absorbed by the wood after a short time should be removed with a clean cloth. Failure to remove any excess stain could result in a blotchy and uneven appearance.
Types of Wood Stains To Use
We have choices to make about the type of stain we’ll use. Two are liquid, and one is pudding-like.
Water-based wood stains
With water as the vehicle, pigment is dissolved/suspended in it. Easy application, resists mold and mildew, and is easy to clean up after – it’s water-based, so a little warm water and soap will take it off your hands easily. It also dries quickly and won’t slow down your project.
Oil-based wood stains
Oil is the vehicle, and it adheres well. However, it also contains chemicals that can be harmful, as well as VOCs (volatile organic chemicals), and you should be wearing a respirator when you are applying an oil stain. The room where you are working should also be very well-ventilated and have good air circulation.
Even with that, though, some of the gas emissions will linger after the stain dries, so keep the air moving even then.
Oil stains do not dry as quickly, and clean up is not as easy, requiring mineral spirits or paint thinner to do so.
Gel wood stains
And now for something completely different, as Monty Python used to say. Gel stains are an oil-based varnish, like polyurethane, with pigment. Gel stains have a pudding-like consistency and must be painted on rather than wiped on with a cloth. As with a liquid stain, any excess should be removed with a clean cloth.
But unlike liquid stains, which are absorbed into the wood, gel stains simply sit on the wood surface (like paint). Since gel stains do not penetrate wood, they tend to provide a more even color and permit the wood’s natural beauty and texture to show through.
To Sand or Not To Sand After Each Coat of Stain
We know we sand between coats of polyurethane topcoats and usually apply at least 2 coats if not 3. We wrote an article about this a while ago, even. But sanding between coats of stain is standard practice, as well, or at least should be.
The Benefits of Sanding
It will give you a more professional-looking project, especially if you have chosen to use a water-based stain. This is because water-based stains raise the wood grain more than oil-based stains do, and we want a smooth surface.
Oil-based stains do not raise the grain, so we suppose sanding between coats when using an oil stain is less necessary, although we still recommend you do sand.
Sanding between coats also improves the appearance of the stain. The application process can lead to bubbles and bumps on the wood surface, and sanding will remove them to leave a better-looking stain job.
Sanding will also help each subsequent coat of stain to bond better with the previous coat. Even the light scruffing up of the earlier coat of stain will create enough of a microscopic rough surface for the next coat of stain to have something to adhere to when applied.
How To Sand or Buff Between Each Coat
When we talk of sanding between coats of stain, we’re not talking about machine sanding or even rough sanding. We used the term “microscopic rough surface” advisedly, as the “roughness” will not be visible to the naked eye.
You won’t be reaching for your random orbital sander for this task. Instead, choose a fine-grit sandpaper and use your hand or a block, but in either case, be gentle. By fine-grit sandpaper, we mean something in the range of 220-grit to 240-grit, as these are the fine-grit sandpaper for the job between coats. They will not gouge or scratch, and your hand touch will be light, also.
Keep in mind that one of the reasons you are sanding is to remove bubbles and bumps, not stain. So, be light and gentle. You’re creating something of a very mildly scuffed surface for the next layer of stain to adhere to when applied. As an alternative, you can also use very fine steel wool to buff the wood’s surface.
Steel wool will remove those bubbles and bumps, as well as a fine-grit sandpaper, and a 0000 grade is an ultra-fine steel wool, perfect for this task.
After sanding or buffing with steel wool, clean the surface well with a clean cloth before applying the next coat. A clean cloth should remove any dust created, and the wood will be ready to receive the next coat.
Which Stains Need Sanding or Buffing?
We’ve already mentioned that a water stain will tend to raise the wood fibers in the grain. These will require some attention before the next coat is applied, whether with that fine-grit sandpaper or the ultra-fine steel wool.
So, sandpaper between coats or steel wool should be the rule – light and gentle to smooth out the bubbles and bumps and to prepare the stain coat for the
Oil stains do not raise the grain of the wood, but there is still the possibility of bubbles or bumps forming during the application of the stain. Since removing them creates a better and more professional final appearance, we do recommend sanding or buffing.
We see no reason not to sand or buff between coats of gel stain except for a bit of laziness. Yes, it’s not necessarily fun, but it is professional, and we do want a good outcome for all of our work. We recommend sanding or buffing between coats of gel stain, too, for all of the same reasons we mentioned for water stains and oil stains.
Video Demo on The Process of Sanding Between Coats of Stain
Short, simple, and direct. This fellow gets it, and in under 2 minutes, what it took all these words to explain.
Go the extra step. Sand between coats of stain, and your project will have a better outcome.