With fresh drywall, the substrate actually absorbs a coating really well, like a sponge. However, because it absorbs so well, without a primer coat, you'll experience uneven coverage, especially along drywall seams. This means you'll need to apply more paint to finally get an even coat.
In many cases, your interior or exterior walls will become flaky and start peeling off. This is one scenario when using primer will help before using paint. Primer not only creates a strong bond between the building materials, it also binds the paint to the wall surface should you choose to paint your wall.
Without primer, paint soaks into the porous surface, weakening it and requiring more coats to get the desired color. Primer is cheaper than paint, so by priming first, you're actually saving money (and time!) from the additional coats of paint you'd need to do to get the same effect.
On new drywall, you will use 3 coats of the finish material instead of a primer coat plus 2 coats of finish. Most projects where you're going over a previously-painted surface do not require the use of a primer.
You probably don't need a primer. If the current wall is smooth, clean and covered with the same type of paint (both are oil-based for example), you can head straight for the paint. You need to fill holes, spackle and sand*, maybe even cut a new piece of drywall in to the existing wall.
Chalk Paint
Like mineral paint, you also don't need to use a primer beforehand. It's another paint type that binds to just about every material or surface, both indoors and outdoors. If you use chalk paint to paint furniture without sanding, adding a top coat finish is recommended.
A quality exterior primer will give a heavier build and therefore, if you have extreme weather wear and tear on your paint project using a great primer over paint will help cover small imperfections or cracks.
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.
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.
A thickness of primer of more than 30 microns is not considered satisfactory as it may diminish its adhesive properties. To obtain a thickness of up to 100 microns, for instance, each coat (one of primer and two of paint) may be around 30–35 microns.
In general, the only time a primer is not needed is if you're re-painting a surface that's in good condition. Your neighborhood Sherwin-Williams paint expert can provide additional advice about selecting and applying the right primer for your project.
If the wall surface is smooth, you can skip the primer step. However, if there are textured areas or wrinkles on the wall, you'll need to prime it first. If your wall has been previously covered in wallpaper, you should definitely plan on using a primer before painting.
Primer will hide the old color so it won't compromise your new shade, and it helps the new color to adhere for solid and even coverage. Self-priming paints will not provide sufficient coverage when there is a drastic color change, so if you don't you prime the walls you'll probably need a third coat of paint.
Primer is often referred to as a base for Foundation or a Foundation primer. They are most commonly used to achieve a controlled matte finish. It isn't necessary to use a Primer before foundation, yet there are many benefits to adding this product into your makeup bag.
In short, you will typically need 2 coats of primer for most painting projects. Apply primer liberally and allow to dry fully before applying your final coat of interior paint. To get more painting advice for your next painting projects, click the link below.
Oil-based primer
The average time for oil-based primers to cure is about 24 hours. The paint will be dry to the touch in a few hours, but it will take longer than that for the primer to harden completely (cure). That's why not a lot of people prefer this type of primer, as it can take longer to dry.
Paint peeling only usually happens when you're trying to paint over an unprimed or poorly primed surface. For those who aren't sure, give yourself a primer drying time of at least 1 hour, or simply leave your model in a dry and clean place overnight.
Too much primer causes a different set of problems. Too many layers or an excessively thick layer increases the risk of the primer cracking, crazing, or chipping. It also takes longer to dry, slowing down your redecorating work. In the worst case scenario, it can damage drywall by causing it to bubble and peel.
Usually one coat of Kilz will be enough to cover any texture issues, stains, previous colors, and odors.
This water-based primer offers enhanced hiding, making it ideal for changing colors and helping to lessen the number of coats of paint required. When painting to hide a previous color, KILZ® Primer reduces the need for multiple coats of paint to allow truer, richer color from your topcoat.
Primer for interior walls is usually a specific type of water-based paint. For new plaster it generally contains good old PVA glue to help seal the wall. An alternative is just to water down the paint you're using to add a light primer coat (mist coat). Especially crucial on new plaster - it drinks the stuff.
On a new wall, you'll want to follow the rule and apply two coats of paint after primer. Follow the same standard for drywall. If you're repainting a wall, you'll only need one coat if you're using the same color and it's a quality paint.
Can you paint over a primer without sanding? Yes, but you shouldn't. Skimp on the sanding results in a rough finish and paint blemishes. However, there're still some specially formulated epoxy primers are not meant to be sand.