Zinsser

Zinsser primer is what goes on a water-stained ceiling, a mildewed bathroom wall, a bleeding pine knot or a slick old cabinet door before the paint, so the problem stays sealed under the finish instead of creeping back through it. Match the primer to the problem: water-base Bulls Eye 1-2-3, oil-base Cover Stain, shellac-base B-I-N, or one of the specialty cans built for a single job, like Mold Killing Primer and Gardz. Contractors and homeowners use all of them.

William Zinsser founded Zinsser in 1849, and the company has been part of Rust-Oleum Corporation since 2008. It’s known for two firsts: B-I-N, the first shellac-based primer-sealer, and Bulls Eye 1-2-3, the first water-based universal primer. Its primers come in four families, water-base, oil-base, shellac-base and specialty, with the specialty lines built around single problems like odor, stains and mold.

Pick the base by the stain

Each Zinsser base is made to stop a different problem. Bulls Eye 1-2-3 seals grease, oily stains and graffiti, and hides handprints and pet grease. Cover Stain seals water, smoke and nicotine stains and stops tannin bleed from wood. B-I-N seals all of those plus ink stains, knots, sap streaks and pet odor. Put simply: water stains, smoke and nicotine go to Cover Stain or B-I-N, pet odor goes to B-I-N, and mold goes to Bulls Eye 1-2-3 or Mold Killing Primer.

The water-base can is tempting when people are living in the house, because it’s low odor and cleans up with soap and water. On grease and handprints, use it. On a water stain, reach for Cover Stain or B-I-N, not Bulls Eye 1-2-3. A water-base primer over a brown leak ring tends to let the ring bleed back through the topcoat, and then the ceiling gets primed and painted twice. The oil or shellac smell fades once the primer dries and the paint goes over it, so on a water stain, open the windows and use Cover Stain or B-I-N.

Mold Killing Primer for bathrooms and basements

Mold Killing Primer does something no ordinary primer does: it kills the mold it goes over. It’s a water-based, EPA-registered fungicidal coating that kills existing mold, mildew, moss, fungi and odor-causing bacteria, and it keeps new mold from growing on the paint film afterward. You paint it straight over the mildew without scrubbing the wall down first, as long as the growth isn’t wet, slimy or heavy. It’s made for non-porous surfaces inside or out, including bathrooms, basements, attics, window frames, baseboards, wall cavities and sub-floors; the one thing it isn’t for is new or unpainted aluminum, metal or vinyl siding. It takes any topcoat, with Zinsser’s Perma-White mildew-proof paint the natural match on top.

It dries to the touch in 30 minutes and takes paint in an hour, and it cleans up with soap and water. A gallon covers roughly 400 to 450 square feet. It comes in quart, gallon and 5 gallon, plus a 13 oz. Mold Blocking Primer spray for a window frame or a corner of a closet.

Two things to know before it goes on. Fix the moisture first, whether that’s a bath fan that doesn’t vent or a basement that took on snowmelt in April, because no primer holds back mold on a wall that keeps getting wet. And it needs the air and the wall at 50°F or warmer, so in a cold basement or unheated space, bring the heat up for the day. Where a heavy water stain sits under the mold, kill the mold with this first, then seal the stain with B-I-N or Cover Stain.

Bulls Eye 1-2-3 for everyday priming

Bulls Eye 1-2-3 is sealer, primer and stain blocker in one, with a flexible acrylic formula that grips and levels well. It goes on drywall, plaster, stucco, cement board, brick and concrete; bare wood, plywood and particleboard; galvanized metal, aluminum, iron and steel; PVC and vinyl; glazed ceramic tile and suspended ceiling tiles. It gets paint to stick on glossy surfaces and over old oil or latex paint, which makes it the primer for repainting shiny enamel cabinets. The primer film resists mold and mildew, and it inhibits rust.

Clear bare wood takes 1-2-3 fine, so there’s no need to buy shellac for every bare-wood job; save B-I-N for the knots.

The gray version belongs under a medium or dark topcoat, where a gray base covers in fewer coats of paint than bright white. Bulls Eye 1-2-3 also works down to 35°F, so a cold garage or unheated addition can still be primed in a Montana fall.

B-I-N for knots, pet odor and the worst stains

B-I-N is shellac-based and dries fast into a rock-hard coat, which is what lets it seal knots, sap streaks, pet urine odor, smoke and musty smells. It sticks without sanding to bare wood, drywall, plaster, metal, PVC and old oil or latex paint, and it’s made for the extreme stain and adhesion problems standard primers struggle with. It’s an interior primer with spot exterior use, like a knot in siding or a patch of trim.

Because it dries so quickly, work fast and keep moving. Soap and water won’t touch it: drips come up with denatured alcohol, and tools wash out in one part household ammonia to three parts water right after use. It’s hard on a good brush all the same, so plenty of painters run cheap brushes and rollers in it and throw them out.

B-I-N comes in a 13 oz. spray, pint, quart, gallon and 5 gallon. The spray is the one for sealing a few knots in pine trim or a single ring on a ceiling without opening a can.

Cover Stain for wood, siding and water damage

Cover Stain is the oil-base primer-sealer painters use on wood siding, trim and cabinets for its grip and stain blocking. It stops tannin bleed in cedar, redwood and other woods, seals exterior wood, and goes on inside or out: masonry, concrete, some brick, metal doors and railings, plaster, drywall, high-moisture areas and glossy or stained wood paneling. On cedar or redwood siding it’s the pick over B-I-N, which is for spot exterior work only.

It blocks ceiling stains from water leaks and smoke damage. Water-stained ceilings and walls after a flood are Cover Stain or B-I-N work. Low-VOC versions dry slower than the regular can, so give them extra time before the topcoat.

Bulls Eye Shellac and SealCoat for wood finishing

Bulls Eye Shellac is where Zinsser started: created in the early 1900s, it popularized shellac as a wood finish and sealer, and it comes in clear and amber, in cans and a spray. It’s a finish in its own right, and Zinsser does not recommend it as a sealer under polyurethane. For that job, use Bulls Eye SealCoat Universal Sanding Sealer. SealCoat is 100% dewaxed shellac, and with no wax in it, it takes any clear topcoat over it, oil- or water-based polyurethane, lacquer or more shellac. It also works as a pre-stain sealer and wood conditioner.

Taking down wallpaper and fixing the wall behind it

Zinsser makes the whole wallpaper job. Run the scoring tool over the paper with light pressure so the remover can soak in without gouging the drywall face. Spray or roll on DIF remover (the gel clings on walls where the liquid runs), let it soak about 15 minutes, and scrape with a wide knife. Wash the old paste off with warm water before you prime, or the paint will crack over it.

Where the drywall paper tore, roll on Gardz before you patch. Mud or paint on raw drywall paper bubbles, and Gardz soaks in and dries to a hard, clear, paintable seal that stops it. It also locks down leftover wallpaper adhesive, skim coats and spackle, it’s water-based and low odor, and it spreads far and dries fast. Hanging new paper? Put Shieldz clear wallpaper primer on first, and the next removal comes off clean.

Prep for every Zinsser primer

Every one wants a surface that’s clean, dry and free of loose or flaking paint. Cover Stain and B-I-N both smell strong, so open windows and run a fan while they go on, and let either one dry thoroughly before a latex topcoat. On anything slick or unfamiliar, like PVC trim or glazed tile, spot-test a small patch and check the grip before priming the whole run.

Zinsser primers side by side

	Bulls Eye 1-2-3	Cover Stain	B-I-N	Mold Killing Primer
Base	Water	Oil	Shellac	Water
What it seals	Grease, oily stains, graffiti	Water, smoke, nicotine, wood tannin	Water, smoke, nicotine, tannin, ink, knots, sap streaks	Kills mold, mildew and odor-causing bacteria
Odor	Low odor	Strong odor, ventilate	Seals pet, smoke and musty odors; strong odor, ventilate	Water-based; ventilate
Where it goes	Drywall, plaster, masonry, wood, metal, PVC, vinyl, glazed tile, glossy paint	Interior and exterior; wood, siding, masonry, metal, plaster, drywall	Interior and spot exterior; wood, drywall, plaster, metal, PVC	Non-porous surfaces inside and out; bathrooms, basements, attics, window frames, baseboards, sub-floors
Drying	Touch 30 minutes, topcoat 1 hour; works down to 35°F	Touch 30 minutes, recoat 1 hour	Dries fast; keep moving	Touch 30 minutes, topcoat 1 hour; apply at 50°F or warmer
Cleanup	Soap and water	Mineral spirits	Denatured alcohol, or ammonia and water	Soap and water

Frequently Asked Questions

How do you use Zinsser Mold Killing Primer?

Fix the leak or condensation that grew the mold first. Then brush, roll or spray the primer straight over the mildew, coating the whole area generously; there’s no need to scrub the wall down unless the growth is wet, slimy or heavy, in which case clean that off and let it dry. Apply it at 50°F or warmer, and put the topcoat on after an hour and within 72 hours for the best protection.

Is Zinsser Mold Killing Primer safe?

It’s an EPA-registered product, and it’s water-based and cleans up with soap and water. It still kills living organisms, so follow the label, keep the room ventilated while it goes on, and wear eye and skin protection and a NIOSH-approved respirator, which Zinsser recommends. If the wall is old enough to have lead paint, don’t sand or scrape it without the lead precautions on the label.

Is Zinsser 123 the same primer as Bulls Eye 1-2-3?

Yes, it’s one water-base primer called by two names at the counter. Besides the cans, it comes in a 13 oz. spray, which is handy for a patched spot or a length of PVC trim.

What is Zinsser Gardz used for?

Gardz is a clear, water-based sealer for problem surfaces: drywall where the paper tore when wallpaper or tape came off, leftover wallpaper adhesive, skim coats and spackle. It soaks in and dries to a hard film you can paint or patch over without bubbles. Roll it on liberally, but don’t flood it.

Is Zinsser Bulls Eye Shellac dewaxed?

No. The regular clear and amber Bulls Eye Shellac is not the dewaxed one, and Zinsser doesn’t recommend it as a sealer under polyurethane. The dewaxed shellac is Bulls Eye SealCoat Universal Sanding Sealer: it’s 100% dewaxed, and with no wax in it, oil- or water-based polyurethane, lacquer or more shellac goes right over it.

Can Zinsser Mold Killing Primer go on wood?

Yes, on painted or sealed wood: window frames, baseboards, sub-floors and table tops are all on its list of uses, along with bathroom and basement walls. It’s made for non-porous surfaces, and the only ones it rules out are new or unpainted aluminum, metal and vinyl siding.

Does Cover Stain come in a spray?

Yes, Zinsser’s oil-base primer comes in a 16 oz. spray for spot work, like one ring on a ceiling or a few tannin streaks on cedar. The spray has the same strong odor as the can, so open a window even for a small job.

Is B-I-N real shellac?

The regular white B-I-N is real shellac, and that’s why it dries so hard and seals so well. For clear sealing over wood, the Bulls Eye clear shellac and SealCoat are the cans to use.

Can Zinsser primer be used as paint?

Don’t leave it as the finish coat. A primer is built to seal and grip, not to take scrubbing, sun and weather the way a topcoat does, so it scuffs, stains and chalks if you leave it bare. Prime, let it dry thoroughly, and then put your paint over it.

What is Zinsser Perma-White?

Perma-White is a water-based interior paint, not a primer, and Zinsser sells it for its mold and mildew resistance. It’s the finish coat for bathroom and basement walls where mildew keeps coming back, and it’s the paint Zinsser pairs with Mold Killing Primer.