Sanding removes imperfection and dirt from surfaces and helps the paint stick better. So, do you have to sand between coats of stain?
Sanding between coats of stain isn’t necessary, but it’s recommended. That’s because the stain has good adhesive qualities, so paint bonding isn’t a problem. However, to get a perfect and smooth finish, you must sand between stain coats.
Also, oil-based stains don’t need sanding between coats but, water-based stains do. This is because water-based stains raise the wood grain and cause bumps in the coating.
Stain Dry Time Before Sanding
The stain must be dry before you sand it. It takes stain between 1-24 hours to dry enough for sanding. On average, you can sand stain within 6-8 hours.
However, the stain dry time depends on the humidity, temperature, and type of stain. For instance, water-based stain dries faster than oil-based stain. That’s because water-based stain uses water as its solvent, and water evaporates faster than oil.
If you sand before the stain is dry, you will ruin the finish. That’s because the paint particles of the stain haven’t hardened yet, so the stain will be sticky and wet. Once you use sandpaper over the wet stain, you will remove most of the stain and create a messy finish.
Use the sandpaper trick to know if the stain is dry enough for sanding. Swipe fine-grit sandpaper over the stain — if the sandpaper gets clogged while sanding, the stain isn’t dry enough. If the sandpaper moves smoothly over the stain, the stain is dry enough for sanding.
However, check the stain container to know the exact dry time before sanding. Usually, the stain dry time (with the best practices) is written on the stain container.
To sand between coats of oil-based stain, use a fine-sandpaper. That’s because oil-based stains don’t need a lot of sanding.
Oil-based stains use synthetic or natural oils as their solvent. Since oil takes a lot of time to evaporate, the stain has enough time to harden and cure. This allows the oil-based stain coats to stick better. However, sanding can improve stain adhesion and produces a smoother finish.
Also, if you take too long to apply another coat of stain, then sanding is necessary. That’s because, while the stain is drying, dust and debris settle over the stain coating. So, if you don’t re-coat the stain for a while, the stain coating will be full of dirt. However, sanding removes the dirt, debris, and any imperfections the stain has, and allows the next coat to stick to a smooth and even coating.
You must sand between coats of water-based stain. That’s because water-based stain tends to raise the wood fibers as the stain dries. The raised wood fibers will become splinters and cause bumps in the stain coating. These bumps will prevent stains from sticking properly.
Also, the water-based stain is thin, so the raised wood fibers will affect the water-based stain more than the oil-based stain. But, sanding will remove these bumps from the stain coating and leave a smooth surface behind for the next stain coating to stick to.
Sanding will also create tiny scratches and marks so the next coat can soak in and adhere. Again, this improves the durability of the water-based stain.
Related Read: How To Apply Stain With a Roller?
Don’t Sand The Final Coat of Stain
You shouldn’t sand the final coat of stain. The final coat of stain gives the wood a unique color and beautifies it, so if you sand it, you will damage the stain and ruin the wood color.
Sanding between coats of stain is advised to improve paint bonding and smoothness. While applying multiple coats of stain, sanding will help smoothen the stain coating so paint adhesion is improved.
However, the final coat of stain shouldn’t be sanded. That’s because you will not apply a stain over the final coat. So, there’s no need to improve paint adhesion.
Sanding the final coat of stain will blur the finish. When you sand, you create sanding dust and tiny scratches over the final coat of the stain. These sanding marks will damage the smoothness of the final coat. The sanding dust will make the finish blurry or cloudy, especially for clear stains.
Eventually, you’ll be left with an amateurish finish.
If You Don’t Sand Between Coats of Stain:
If you don’t sand between coats of stain, the new coat won’t stick properly. Also, the finish won’t be smooth or clear. That’s because the dust nibs, splinters, and debris will affect the quality of the finish.
Dust, debris, and splinters will settle and dry on the existing stain coating, making it difficult to have a smooth and perfectly bonded finish. This is why it’s required to sand lightly between coats of stain, regardless of the type.
Sanding removes imperfections, dust, debris, and splinters from the stained surface. This allows the next stain coat to stick better and last longer.
Use Fine-Grit Sandpaper
You must use ultra-fine grit sandpaper for sanding between stain coats. This includes grit of 320 and above. You can also use fine-grit sandpaper, but you must be careful.
However, you shouldn’t use coarse and medium-grit sandpaper for sanding stained wood. That’s because coarse and medium-grit sandpaper will remove the stain instead of smoothing it out. This includes sandpaper with a 150-grit and below.
You must apply stain in thin coats because thick coats will be difficult to control. So, if you sand thin coats of stain with coarse or medium sandpaper, you will ruin the finish.
When sanding between coats of stain, you need fine-grit sandpaper. That’s because you only need to remove the imperfections, dust, and debris from the stain coating, not the entire coating.
However, before staining wood, you must use medium-grit sandpaper. That’s because unstained wood has a lot of imperfections, bumps, and dirt on the surface, and medium-grit sandpaper will remove all of these. For rough timber wood, you can use 100-grit sandpaper.
Also, most wood furniture are riddled with glue, pencil marks, nail holes, and splinters. All of these things can affect the quality of the stain finish. So, you must use medium-grit sandpaper to remove all.
Fine-grit sandpaper won’t remove the large imperfections, pencil marks, or dirt from the wooden surface. You can only use fine-grit sandpaper if the wooden surface is smooth and even before staining.
Tip: Sand in the direction of the wood grain.
You must sand between coats of stain, and before applying stain. Sanding will help remove bumps from the surface and leave a smooth surface behind for the stain to stick to.
If you don’t sand between coats of stain, multiple stain coatings won’t adhere, and you will end up with a sticky stain. However, sanding after staining isn’t required, the final coat of stain must be as clear as possible.