Paint Primer Guide

Primer doesn't get talked about much, but it's the reason some paint jobs look flawless and others look patchy after six months. It seals surfaces, blocks stains, and gives paint something to grab onto. That said, you don't always need it.

When You Absolutely Need Primer

• New drywall: Bare drywall soaks up paint unevenly. Primer seals it so you get uniform coverage.
• Dark to light color change: Navy to white without primer? You'll be on coat number four wondering where your weekend went. Primer blocks the dark color and saves you paint.
• Stained walls: Water stains, smoke, crayon, markers — primer blocks them so they don't bleed through.
• Glossy surfaces: Paint won't stick to semi-gloss. A bonding primer gives it something to hold onto.
• Wood or metal: These need specialty primers — oil-based or shellac.

When You Can Save the Money

• Repainting over the same or similar color on previously painted walls.
• Using a good paint-and-primer combo on well-prepped surfaces.
• Light-to-light color changes (beige over off-white, for example).

How Much Primer?

Primer covers 200–300 sq ft per gallon — less than paint because it soaks into the surface. For a 12×12 room, figure about 1.5 gallons. Always buy a little more than you think — running out of primer mid-job is just as annoying as running out of paint.

Types of Primer

• Water-based (latex): Good for drywall and previously painted surfaces. Low odor, easy cleanup with water.
• Oil-based: Best for wood, stubborn stains, and adhesion. Stronger smell. Clean up with mineral spirits.
• Shellac: The nuclear option for stains. Covers smoke, water damage, and wood knots. Dries fast but stinks to high heaven.