Do You Need Primer? How to Choose the Right Primer for Any Surface

Primer is the coat nobody sees, but it decides whether your paint sticks, covers evenly and lasts. It's also the step people most want to skip. Sometimes you can. Often you can't. And picking the wrong primer can be as bad as using none.

This guide explains when you really need a primer, what each type does, and which one to use for drywall, wood, stains, slick surfaces and big colour changes. It's for homeowners and painters alike.

What primer actually does

A good primer does one or more of four jobs:

• Seals. Bare drywall, patches and raw wood soak up paint unevenly, which leaves blotchy, uneven sheen (called flashing). Primer evens out the surface so the topcoat looks uniform.
• Sticks. Paint doesn't grip glossy, slick or non-porous surfaces well. A bonding primer gives it something to hold onto.
• Blocks. Water stains, smoke, marker, knots and the tannins in cedar and redwood bleed right through ordinary paint. A stain-blocking primer locks them in.
• Hides. A high-hiding primer covers the old colour, so you need fewer coats of your more expensive topcoat.

Which primer do you need?

Find your situation, then use the primer beside it.

Painting cabinets? Our kitchen cabinet guide has a primer table just for cabinets, including when you can skip primer with INSL-X Cabinet Coat.

The main types of primer

Water-based (acrylic)

Low odour, fast drying and easy soap-and-water clean-up. Today's acrylic primers handle most jobs, including many stains and glossy surfaces. Examples: Fresh Start High-Hiding, Aqua Lock Plus, Zinsser Bulls Eye 1-2-3 and KILZ Restoration.

Oil-based (alkyd)

The heavy hitters for stain blocking: heavy water and smoke damage, and tannin bleed on cedar and redwood. They have more odour and clean up with mineral spirits. Examples: INSL-X Prime Lock Plus, Zinsser Cover-Stain and Zinsser Odorless Oil-Base for indoor spaces where odour matters.

Shellac

The specialist for knots, sap streaks and odours. It dries very fast and seals almost anything, but it has a strong smell while wet and is mainly for interior and spot exterior use. Example: Zinsser B-I-N.

Bonding

Made to grip surfaces other primers slide off: laminate, tile, PVC, glass and galvanized metal. Example: INSL-X Stix, which also cures in cold weather. Read our Stix guide for painting slick surfaces.

Our primers side by side

Recoat times are at normal room temperature. Cool or humid weather takes longer.

Should you tint your primer?

Often, yes. A primer tinted toward your topcoat colour helps the paint cover in fewer coats, especially with deep reds, yellows and other bright colours. Fresh Start High-Hiding can be tinted, and Aqua Lock Plus, Prime Lock Plus and Stix can be lightly tinted (up to 2 oz per 3.79 L). For very deep colours, Aqua Lock Plus also comes in black. Tell us your topcoat colour when you order and we'll tint to match.

How to prime, step by step

1. Clean. Wash off dirt, grease and mildew. Primer won't stick to grime, and a degreaser is a must in kitchens.
2. Repair. Scrape off loose paint, fill holes and cracks, and sand patches smooth.
3. Dull glossy areas. A light scuff-sand helps even bonding primers grip better.
4. Remove the dust. Vacuum and wipe down so dust doesn't end up in your finish.
5. Apply one even coat. Brush, roll or spray, and follow the can's temperature range. Add a second coat for drastic colour changes or heavy stains.
6. Let it dry, then sand any nibs lightly with a fine sponge.
7. Topcoat once the primer is ready to recoat. Two coats of a quality paint give the best result.

Priming bare wood

Bare wood needs a little extra care, inside and out:

• Check the moisture. Painting wet wood is a recipe for peeling. As a rule of thumb, interior wood should be about 12 to 15% moisture and exterior wood no more than 15 to 20%. A moisture meter is cheap insurance.
• Remove sap. Scrape off any dried or oozing sap, especially on pine and fir.
• Spot-prime the knots with a shellac primer like B-I-N, or they'll bleed through as yellow-brown circles.
• Fill and sand. Use a quality filler like Timbermate, which won't shrink or crack, and sand with 150 to 220 grit, always along the grain.
• Prime the whole surface with the right primer for the job (see the table above).

Staining instead of painting? Skip the primer. Stain needs to soak into bare wood. See our deck stain guide for exterior wood prep.

What about paint-and-primer in one?

Paint-and-primer products work best over sound, previously painted surfaces in a similar colour. They aren't a substitute for a real primer on bare drywall, raw wood, stains, slick surfaces or dramatic colour changes. When in doubt, prime.

Common primer mistakes

• Skipping primer on new drywall. The mud and paper absorb paint differently, so the joints show through as dull or shiny patches.
• Using the wrong type. A general primer won't stop cedar tannin or heavy smoke stains. Match the primer to the problem.
• Priming over dirt or grease. Primer only sticks as well as the surface underneath it.
• Not tinting for deep colours. A white primer under a deep red can mean three or four topcoats.
• Waiting too long. Some primers have a window for topcoating. Check the can.
• Priming wood you plan to stain. The stain can't penetrate, so it sits on top and fails.

FAQ

Product details are from Benjamin Moore, INSL-X, Zinsser, KILZ and XIM. Always follow the directions on the can and the product data sheet.