I was about to lay the second coat of lacquer stain on my wife’s drawer. But I wasn’t sure if I needed to sand the first coat before doing that. So I made some research and here is what I found out.
You don’t need to sand between coats of stain. This is because multiple coats of stain will adhere. So paint bonding isn’t a problem.
However, to achieve a perfectly bonded and smooth finish, sanding between coats is needed.
Also, oil-based stains don’t usually need sanding between coats. But water-based stains do. This is because water-based stains tend to raise the wood grain and cause bumps in the coating.
How Long Should Stain Dry Before Sanding?
The coat of stain has to dry till the stain cures before you can sand.
It takes between one and 24 hours for stain to dry enough for sanding. On average, most stains will cure and can be sanded in 6 hours provided the stain was applied correctly and at room temperature.
Sanding stain that hasn’t cured or dried enough will ruin the stain and make the finish appear amateurish. The finish will also be tacky and uneven.
Before you can sand stain regardless of the type, the existing coating should have cured first.
Stain coating will cure when the solvent in the paint particles is evaporated. The reason for waiting till stain coating cures before sanding is to prevent ruining the finish.
It usually takes longer for oil-based stains to cure than water-based stains. This is because oil-based stains contain natural and synthetic oils as well as a large volume of chemicals that will take hours to leave the stain coating.
Water-based stains on the other hand usually dry within 3 hours because the stain doesn’t contain oils or as many chemicals as oil-based stains. Water-based stains use water as the solvent and water evaporates quicker than oil.
So for water-based stains, you can often sand the first coat after 3 hours. But for oil-based stains, you’ll need to wait longer before sanding.
Overall, the time it takes before you can sand the stain that you applied depends on the manufacturer’s instructions which are indicated on the stain’s container.
Should I Sand Between Coats of Oil-based Stain?
You should sand lightly with very fine sandpaper between coats of oil-based stains. Oil-based stains don’t usually need to be sanded between coats.
This is because the oily nature of the stain gives it enough time to cure and harden. This makes it easier for successive coats of the oil-based stain to adhere. However, sanding between coats of oil-based stain will produce a smoother and perfectly bonded finish.
Oil-based stains like lacquer, gel, wax, and polyurethane don’t need sanding between coats for different reasons.
For starters, oil-based stains have good bonding qualities. This is because oil-based stains are the most common choice of stain. As a result, oil stains are usually designed with great bonding qualities to allow use on several types of surfaces.
Also, oil stains take very long to dry due to the oil-based nature of the solvent. This prolonged drying time helps the stain coating dry properly to previous coatings without the need to sand.
However, sanding oil stains is advised to achieve a perfectly bonded and smooth finish. Here is why – oil stains take a long time to dry.
Though this prolonged drying time helps the stain to dry properly, it also allows dust nibs and debris to settle on the stain while it is drying.
So sanding between coats of oil stain helps to remove these dust nibs and grain. This will result in a smoother and fine oily finish.
Should I Sand Between Coats of Water-Based Stain?
You should sand between coats of water-based stain. This is because water-based stains tend to raise wood fibers as the stain dries. These raised wood fibers will become splinters and cause bumps in the stain coating after it has dried.
So, before applying the next coat, these raised fibers have to be sanded off to create a smooth surface for the next coat to adhere to.
Also, water-based stains are not usually as thick as oil-based stains. This means the raised wood fibers in addition to causing a rough finish will not allow proper paint adhesion.
So, you need to sand between coats of water-based stain to create tiny marks and scratches that the next coat can soak in and adhere to. This improves the durability of the water-based stain.
Related Read: How To Apply Stain With a Roller?
Do You Have To Sand The Last Coat of Stain?
You don’t need to sand the last coat of stain. The last coat of stain regardless of the type of stain shouldn’t be sanded. This is because sanding the final coat of stain will damage the stain.
Sanding between coats of stain is usually advised to improve paint bonding and smoothness. While applying multiple coats of stain, sanding will help to smoothen out the stain coating so paint adhesion is improved.
However, the final coat of stain shouldn’t be sanded. This is because you are not going to apply any stain or coating on the final coat. So there is no need to improve paint adhesion.
Also, sanding the final coat of stain will blur the finish. When you sand, you create tiny scratches and sanding dust on the final coat of the stain. These sanding marks will damage the smoothness of the final coat.
The sanding dust will also make the finish blurry or cloudy especially for clear stains.
Eventually, you’ll be left with an amateurish finish.
What Happens If You Don’t Sand Between Coats of Stain?
If you don’t sand between coats of stain, then the new coat will not adhere to the existing coating properly. Also, the resulting finish will not be perfectly smooth and clear. This is because of dust nibs, splinters, and debris that appeared on the existing coating after it dried.
These imperfections settle and dry on the existing coating of stain 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.
When it comes to staining surfaces especially wood, DIYers tend to just put on the finishing coat of stain without sanding between coats. The belief is the clear coat doesn’t require sanding. Another reason is they believe sanding will ruin the finish. Both statements are false.
Related Read: Do You Need To Sand Polyurethane Paint Coats?
What Grit Sandpaper Should I Use To Sand Between Coats of Stain?
You should use ultra-fine grit to sand between coats of stain. This includes grit of 320 and above. Fine grit sandpaper will work too but it requires caution. Coarse grit and medium-grit sandpaper will ruin the stain. This includes sandpaper from 150 grit downwards
When sanding between coats of stain, you need the finest grit possible. This is because coarse sandpaper will remove the entire coating. Medium-grit sandpaper will also ruin the finish but might not remove it entirely.
Stain is applied in light and thin coats. Thick coats will be difficult to control. The thinness of the stain coating makes it very vulnerable to coarse sandpaper. Ultra-fine sandpaper on the other hand will sand the stain smoothly.
What Grit Sandpaper Should I Use Before Staining Wood?
For fresh wood, painters advise you to start with medium-grit sandpaper and then work your way up to fine-grit sandpaper. Very rough timber can be sanded first with 100 grit sandpaper.
The medium-grit sandpaper will seal holes and gouges in the wood. It will also remove bumps and paint pimples if there is any on the wood.
Then the fine-grit sandpaper will even out grain and smoothen the wood before the stain or primer is applied.
Tip: Remember to sand in the direction of the wood grain.
Before wood is stained or painted, there are usually a lot of foreign objects and imperfections in the wood.
Furniture especially is usually riddled with glue, pencil marks, nail holes, splinters, and the sort. All of these objects and imperfections come from the carpenter’s shop while the furniture was being made.
If you apply paint or stain on fresh wood without sanding, the result will be ugly.
Related Read: Do You Need To Sand Paint Before Applying Polycrylic?
Overall, it’s important to note that not sanding between coats of stain is still okay to do, for a rough task that is. If you are finishing a wooden decor, furniture, or any other surface that requires a fine finish, sanding between coats of stain is necessary.