Home Improvement Interior Remodel Walls & Ceilings Drywall

Drywall Primer Basics and Application

Priming is a required first step before many painting jobs. Many surfaces, especially those that are in poor condition, benefit from a full coat of primer. Bare drywall, straight from the manufacturer and recently installed, doesn't seem like a poor surface, though. Does drywall need a primer? If so, what type of drywall primer and how should it be applied?

primer for drywall

The Spruce / Margot Cavin 

Is Primer For Drywall Necessary?

New, unpainted drywall requires priming with a drywall primer before painting. Painted drywall may or may not require a primer, depending on the condition of the paint.

Unpainted Drywall

Bare drywall is defined as drywall with unpainted, unprimed face paper, as shipped from the factory. Since it is installed, it also has taped seams covered with drywall compound (mud). In addition, its fastener holes have been filled with mud, Paint manufacturers usually recommend a primer.

Priming drywall is fast, inexpensive, and effective. Along with a dedicated drywall primer, there are a number of other easy ways to prepare drywall before painting: flat latex paint, hiding paints, and skim-coating with drywall compound.

Painted Drywall

Painted drywall may not need a primer if the surface is clean and in good condition. Glossy surfaces may require a primer. When changing from a dark paint color to a lighter paint color, primer reduces the number of color coats needed.

Drywall Primer Options
Product Features
Drywall primer-sealer Designed specifically for sealing drywall paper surfaces
Flat latex paint Inexpensive option for priming drywall
Hiding paint High-build paint designed for problem surfaces
Skim coat Drywall compound applied with a drywall knife smooths the surface but isn't a primer substitute

What Drywall Primer Does

Drywall primer helps the paint's color coat begin with just one color, instead of several colors, by standardizing bare drywall's variegated color scheme. Primer sets another kind of standard: porosity. With added primer, drywall soaks in the paint at one speed, not several speeds.

Primer Equalizes Color

Primer equalizes colors of drywall mud and paper so that the paint colors laid over it can truly shine without interference. Primer's color sets a base standard for all of the other colors to work off of.

With newly finished drywall, there are two base colors: the color of the paper (gray, off-white, or green) and the color of the drywall compound or mud (white or off-white). One coat of primer or even an inexpensive neutral-colored paint will go a long way towards covering up these colors. A better quality (thicker) drywall primer, also known as a hiding paint, will cover them up completely.

Primer Equalizes Porosity

Drywall primer soaks into the paper, scuffed paper, and mud—the areas of differing porosity—and creates a uniform surface to which the finish paint can adhere.

If you have ever looked at a painted wall from a sharp angle and seen the finished joints show through, this is an effect called joint banding or flashing. Drywall primer will significantly reduce or completely eliminate that effect.

Primer Products

The most common way to prime bare drywall is with a 100-percent acrylic drywall primer-sealer or with a PVA primer.

Drywall Primer-Sealer

A coat of 100-percent acrylic primer-sealer is recommended for new drywall. Drywall primer-sealers come in water-based (latex) and oil-based (alkyd) forms.

Choose between standard sealers, which are appropriate for perfectly smooth and well-finished walls, or high-build primer-sealers that fill in rough or uneven drywall finishing. The high-build products cost quite a bit more, but they may be worth the expense, especially when preparing a drywall surface that is rough. 

Tip

To improve coverage and quality, primer-sealers can be tinted before applying, so that the primer coat is a closer match to the color of the finish paint. Paint stores may be able to add pigments to the sealer-primer, sometimes for a small additional fee. 

PVA Drywall Primers

PVA (polyvinyl acetate) primers create a synthetic, rubber-like thin film that effectively seals highly porous drywall paper. PVA primers grab onto drywall paper better than latex paint does.

PVA primers are used for many porous surfaces before paint application: brick, stone, all masonry, but not wood.

PVAs are sealers that aid with adhesion more than they are color blockers. PVAs may incidentally cover stains and discolorations but that's not their job. As such, stains may lightly show through.

Flat Latex Paint

Using flat latex paint is another inexpensive way to prime drywall before painting. Even pros sometimes opt for cheap latex paint as a primer when the surface has been so well finished that the surface is perfectly smooth without flaws. Some drywall manufacturers even recommend plain flat latex paint as one type of drywall primer.

The cost of a gallon of basic flat latex paint is usually considerably less than that of top-quality finish paint. As with the primer-sealer, one can tint the flat white latex paint to more closely match the finish color.

Hiding Paints

Hiding paints take the concept of flat latex paint one step further. This product is still a flat latex paint, but it is slightly thicker and has better color-hiding properties than plain latex paint.

Choose a hiding paint that is compatible with unfinished drywall. Hiding paints may cost up to twice as much as ordinary flat latex paint.

Cost Savings

Drywall primers will cost $20 to $25 per gallon. Premium paints cost $60 to $100 per gallon. Drywall primers cost three to four times less per coat when compared to premium-paint color coats.

How Drywall Primer Helps Color Coats

New, freshly finished drywall is difficult to paint directly because the surface presents three different textures, each with its own rate of absorption.

  • Taped and mudded seams and screw holes have been covered with drywall compound (mud) and they tend to absorb paint.
  • Drywall is faced with paper. Because paper is porous, it absorbs paint.
  • Overly sanded drywall paper—often, the areas near the mudded seams—may have a scuffed, fuzzy surface that also tends to absorb paint.

The result is that when you paint directly onto bare, finished wallboard, these different rates of absorption will produce a mottled, streaked look where certain areas show through, a condition called flashing.

This unevenness only disappears after multiple layers of expensive paint. Depending on the color and glossiness of the paint, it can sometimes take three or even four coats before the painted surface is uniform. 

FAQ
  • Can you skim-coat instead of use a drywall primer?

    Skim-coating is the process of using a drywall taping knife to scrape drywall compound on the drywall and then immediately off. Skim coating cannot be done in lieu of priming; a prime coat would still be needed over a skim coated wall.

  • What kind of primer do you use on drywall?

    Use either a dedicated drywall primer or a PVA sealer on bare, unfinished drywall.

  • How many gallons of drywall primer do I need for new drywall?

    One gallon of drywall primer covers 250 to 400 square feet of new drywall.