You should sand after the first coat of water-based stain to flatten any wood grain the water raised, but it's unnecessary after that. You don't need to sand between coats of gel stain or oil-based stain.
However, keep in mind that if you sand too much, you are going to lose the color and protective nature of the layer of stain that you just put on. It is best to sand very lightly, using very fine sandpaper like 220 grit.
The way to get the smoothest and best-feeling finish is to “rub out” the last coat using sandpaper and abrasive compounds. Methods of doing this are written about often. It's a mechanical procedure that doesn't differ all that much from sanding the wood.
Originally Answered: Should you lightly sand stained wood before applying a polyerthane coat ? Yes, lightly sand with 400 grit sand paper and use a tack cloth to remove any dust. If you do not have one, spray a clean rag with a little clear lacquer.
Sand to a coarser grit. To get a darker coloring with any stain when you are wiping off the excess, sand to a coarser grit. More of the colorant will lodge in the sanding scratches, producing a darker effect.
Most stains should be sealed to prevent bleeding. After smoothing the stained wood, apply a sealer coat of thinned shellac, sanding sealer, or other appropriate sealer. Do not use shellac with NGR or water-base stains. If you plan to finish the piece with polyurethane, make sure the sealer is compatible.
If you don't sand between layers of polyurethane, the surface may become streaky or discolored. This formula prevents chemical solvents from bonding to it. Once the first layer of paint is dry, you can apply a second coat to make sure everything remains. Each coat of oil-based polyurethane finishes is applied on top.
Light sanding will remove darkness from wood stain.
While staining creates a rich, deep color that highlights natural wood grain, it does not provide long-term protection. Without a protective top coat, wood can be damaged easily due to contact with water, food, or sharp objects. A polyurethane top coat protects the wood from scratches, stains and water damage.
Whenever water or any stain or finish that contains water comes in contact with wood, it causes the wood fibers to swell, which is called “grain raising” or “raised grain.” After the water has dried the wood feels rough to the touch, and thinly applied finishes also feel rough.
Sealing stained wood with Polycrylic
Polycrylic is a very popular sealant for wood projects. It is inexpensive and easy to apply. It provides strong coverage and is, in general, a great choice.
The best option is to use a varnish or lacquer to give the wood a high gloss finish. While varnish can be sprayed or brushed on, lacquer is best applied by simple spraying.
Water-based stains usually take 4 to 6 hours to dry, while oil and gel-based stains can take up to 12 to 24 hours.
Before you even finish your wood project with wood stain or paint, for best results, make sure that it is sanded well and has a smooth surface. This is extremely important for not just the polyurethane top coat, but for the best wood stain or paint application too!
Stains lighten as they dry, then return to their damp color when a finish is applied. So the quick method of seeing the color you'll get with the finish applied is to look at the stain while it is still damp. If you're using a satin or flat finish, however, you need to factor in the impact of the flatting agent.
Start by sanding your piece down to the raw wood. This is extremely tedious and time consuming on a large piece. However, it will give you the best outcome if you're looking for a very raw and organic color in the end. Begin with 60 or 80 grit sandpaper to take off the finish as quickly as possible.
The surface can discolor or dry streaky if you don't sand between coats of polyurethane. The formula inhibits the bonding of chemical solvents. And when its initial layer of paint has dried, a second can be applied to ensure everything stays.
To give the subsequent poly layers something to bond to, sand lightly between coats with 320-grit sandpaper wrapped around a hard block.
As a general rule of thumb, you should apply at least two coats of polyurethane. If you are working on furniture or floors, you should apply at least three coats. You may even use spray paint for the wooden flooring. A water-based polyurethane could be applied for up four or five coats.
Add a Protective Coat
After the stain has dried and you like the result, apply a protective coat. Remember, the top coat should be the same as your pre-stain and stain – oil-based to oil-based, water-based to water-based. This example uses a clear coat polyurethane for the finishing coat.
We always recommend two coats of stain for any wood project, but you should only apply as much stain as the wood can absorb. Extremely dense hardwoods may only be able to absorb one coat of wood stain. The general rule of thumb is to apply only as much deck stain as the wood can absorb.
Depending on the type of stain you are using, most stains are dry and cured within 24 hours to 48 hours. After that time, it's safe for additional coats or to apply polyurethane or the sealer of your choice.