Whether you wet sand primer or not depends entirely on what type of primer you're sanding. For latex paint primer (water, oil or shellac-based,) you don't need to wet sand, since the layer of paint will cover that perfectly smooth surface anyway. Auto-body primer, on the other hand, should be wet sanded.
All primer and filler coats must be thoroughly hard dry before any sanding and final preparation is carried out. Final sanding before applying colour coats is generally carried out wet using the appropriate fine grades of WetorDry abrasive paper.
The quick answer to the question, “Do I need to sand primer before painting my wall?” is YES. Primer should be sanded before you apply the paint. A primer is used to help cover up the existing color of your wall. It is applied to create a blank, neutral surface before you coat your wall with your chosen paint color.
For your finish to be vibrant and not dull sanding after primer will ensure that the finish is not excessively dulled when you apply your paint top coat. You will typically use finer grit sandpaper and aim to achieve a smooth wood finish so that you get a fine appearing wood finish when you apply your topcoat.
For best results, allow to Primer to dry for 1 hour before dry sanding. Test in an inconspicuous area to be sure Primer is dry enough for sanding. Block sand the area using 320-400 grit sandpaper.
My preference is to use 220 grit sandpaper and sand in the direction of the grain. You don't need to sand too hard, just enough to scuff up the surface and dull the shine.
Sanding a surface removes the top glossy layer, allowing the substance to receive the primer. Without sanding the surface in advance, the new coat of paint won't stick to the previous layer.
Sanding after applying primer should help keep your surface as smooth and flat as possible, eliminating brush marks, or extra little globs. Also when painting, like others have pointed out, can raise little fibers from the drywall, going over the surface with a sheet of sandpaper can help get rid of those lose fibers.
Essentially, wet sanding is the process of sanding a car with water. The water acts as a lubricant and vehicle to remove the paint dust that would normally just clog up the sandpaper and get in the way.
You will want to use 2-3 coats of primer to ensure there is a good bond between the new paint and the wall, and also to cover up any previous colors, especially if they are red, orange, or a strange outdated color. In short, you will typically need 2 coats of primer for most painting projects.
600 grit and 800 grit are used for sanding imperfections in the primer before applying the base coat/paint. Start with 600 grit and work your way up to 800 grit. You can use 1,000 grit or 1,200 grit over the base coat to remove imperfections.
Most latex primers dry to the touch in 30 minutes to one hour. But for best results, don't paint until the primer completely dries—which can take up to 3 hours, depending on temperature and humidity. Once the primer is completely dry, it's prime time for painting.
You can't paint over tacky primer, so sometimes you might want to speed up the primer's dry time. The drying time of an oil-based primer depends on the temperature, ventilation, and humidity level of the painted surface.
It may be necessary to sand down your car again after the primer is dried. Many times applying the primer can cause mounds or dips in areas and you want to smooth these out as much as possible.
Absolutely yes. Assuming you want a first class finish coat. Use a finer sandpaper than you did on the first coat of primer.
However, many professional painters do recommend sanding after all the coats of primer are done. Only after the primer as a whole has dried through its many coats, you could sand it to further ensure that the surface is completely smooth and free of debris.
A minimum of two coats of PVA primer is necessary when painting new drywall in order to prevent the paint finish from looking splotchy and uneven after drying. New drywall is like a sponge, and it's better to let it soak up inexpensive primer than expensive paint.
Choose fine sandpaper for the best results
We recommend 120-grit or 150-grit paper for the best results. Buy precut sheets made to fit your hand sander. It also fits half sheets of standard size paper.
Sanding your door well, before priming and painting, is the right way to do it. Sanding will create a smooth surface that will help your paint to look great.
If you're painting wood without a stain or finish, use a latex or an oil-based primer for the best results. Don't over or under apply the primer: You should aim to apply two coats of primer to your wood's surface. Brush the primer on, and allow the first coat to dry completely before adding the second coat.
As Phillips mentioned, you want to wait a full minute or more to allow the primer to dry completely before going in with makeup, as this will help to curb pilling or patchiness. Another mistake people make is choosing a primer that's wrong for their skin type.
Depending on how strong or bold the previous color is, it may be necessary to apply more than one coat of primer. However, it is not necessary to over apply the primer with so many coats. As long as the primer applies uniformly over the previous color, then one or two coats should be sufficient.