Flex Seal Primers

Flex Seal Stain Blocking Primer Stop the stain before you paint.

This fast-drying spray primer seals water, smoke, tannin, ink, and grease stains so they won't bleed through. Paint-ready in as little as 1 hour.

Buy Now —$9.99

  • Blocks Tough Stains

    Helps stop stains from bleeding through paint.

  • Paintable

    Compatible with latex and oil-based paints.

  • Fast Drying

    Dry to the touch in 15–30 minutes and paint-ready in 1 hour.

  • Interior & Exterior Use

    Great for walls, ceilings, wood, masonry & more.

Why It Works

Tough on Stains. Easy to Use.

Spraying Flex Seal Stain Blocking Primer over a brown water stain on a ceiling

Blocks Tough Stains

Helps prevent stains from showing through your new coat of paint. Seals water, smoke, nicotine, tannin, ink, and grease stains.

Wood trim board primed bright white with Flex Seal Stain Blocking Primer, ready for paint

Paint the Same Day

Dry to the touch in 15–30 minutes and paint-ready in as little as 1 hour.

Spraying an even coat of Flex Seal Stain Blocking Primer into the corner of a wood cabinet

Easy Spray Application

Great for spot priming, trim, corners, and hard-to-reach areas. No brushes or rollers to clean.

Stains It Blocks

See the Stain Disappear.

Choose a stain, then drag the slider to see the results after priming with Flex Seal Stain Blocking Primer and painting.

Ceiling after priming with Flex Seal Stain Blocking Primer and painting: clean, bright white Ceiling before priming: brown water stain

Found onCeilings, drywall and plaster

After photos show the surface primed with 2–3 thin coats, left to dry, then painted.
Results vary by stain and surface.

Gloved hand spraying Flex Seal Stain Blocking Primer onto wood boards on sawhorses

How It Works

How to Apply

Prep your surface, spray the primer, then let it dry before painting.

  1. Prep

    Make sure the surface is clean, dry, and free of grease, wax, and peeling paint.

  2. Spray

    Shake the can for 1 minute. Hold it 12 inches from the surface and spray side to side in an even motion, applying 2–3 thin coats. After use, turn the can upside down and spray to help prevent nozzle clogs.

  3. Let Dry & Paint

    Dry to the touch in 15–30 minutes and paint-ready in as little as 1 hour. Topcoat with latex or oil-based paint.

Flex Seal Stain Blocking Primer, white, 12 oz aerosol can
Flex Seal Stain Blocking Primer can: blocks tough stains, prevents bleed-through, paint-ready in 1 hour, interior and exterior use
Spraying Stain Blocking Primer over a water stain: stop stains before they show
Before and after: wood trim primed with Stain Blocking Primer
Works on new and repaired drywall, bare and painted wood, plaster and ceilings, masonry, brick and stucco
How to use: 1 prep, 2 spray, 3 let dry and paint
From the makers of Flex Seal: tested and proven, millions sold, satisfaction guaranteed

Flex Seal Stain Blocking Primer

12 oz · Flat finish · Covers 6–8 sq ft

$9.99

Color: White

White, Stain Blocking Primer, selected Gray, Metal and Auto Primer

Gray is our Metal & Auto Primer →

12 oz Flat finish Covers 6–8 sq ft

$9.99

  • Blocks water, smoke, nicotine, tannin, ink and grease stains
  • Paint-ready in as little as 1 hour
  • Works under latex or oil-based paint, indoors and outdoors.
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Details

Flex Seal Primer with Stain Blocker is a fast-drying, oil-based alkyd spray primer that seals and primes interior and exterior surfaces before finish painting. Its powerful stain-blocking formula blocks most heavy stains, including water, smoke, nicotine, tannin, ink, pencil, felt marker and grease. It dries to a bright white, flat, paint-ready base for spot priming, stain isolation and full-surface paint prep.

Use on: New and repaired drywall and plaster, bare and previously painted wood, paneling and hardboard, wallpaper, masonry, brick, concrete, stucco, metal, vinyl siding, soffits, moulding and fascia. Scuff-sand glossy surfaces first.

Not for: Floors, decks, or surfaces that sit in water or get prolonged water contact.

Specifications
Size12 oz (340 g) aerosol
Color / finishBright white, flat
Coverage6–8 sq ft per can
BaseOil-based alkyd
Dry to touch15–30 minutes
Topcoat readyIn as little as 1 hour
Full cure24 hours
TopcoatsLatex or oil-based
Apply between50°F and 90°F
UseInterior and exterior

Dry times at 77°F and 50% relative humidity.

Directions
  1. Read all directions and warnings before use. Wear gloves and eye protection and work in a well-ventilated area.
  2. Make sure the surface is clean, dry, and free of dust, dirt, grease, oil, and wax. Scrape away any loose or peeling paint and sand smooth. Wash if needed, then rinse and dry completely.
  3. Shake the can vigorously for 1 minute after the mixing ball rattles. Shake frequently during use.
  4. Hold the can upright about 12 inches (30 cm) from the surface. Spray in a steady side-to-side sweeping motion, overlapping each pass by 50%.
  5. Apply 2–3 thin coats. Do not over-apply.
  6. Dry to the touch in 15–30 minutes at 77°F and 50% relative humidity. Recoat in 1 hour. Ready for latex or oil-based topcoats after 1 hour.
  7. After use, turn the can upside down and spray until only clear gas releases to clear the valve.
  8. Clean fresh overspray immediately with mineral spirits or paint thinner.
Safety & Storage

Danger: Extremely flammable. Contents under pressure. Keep away from heat, sparks and open flame. Use only in a well-ventilated area. Wear eye protection and gloves. Keep out of reach of children. Do not store above 120°F.

Warning: If you scrape, sand or remove old paint, you may release lead dust. Lead is toxic. For more information, visit epa.gov/lead.

WARNING: California Prop 65 Notice

FAQs

Stain Blocking Primer Questions Answered.

It depends on the surface. Use Stain Blocking Primer (white) on walls, ceilings, wood and masonry, when you need to cover stains like water, smoke or grease so they don't bleed through your paint. Use Metal & Auto Primer (gray) on cars and bare or coated metal: it's rust-inhibiting, sandable in 5 minutes and paint-ready in 10. Shop Metal & Auto Primer →
Also sold as Flex Seal Primer with Stain Blocker, it's a fast-drying, oil-based alkyd spray primer that seals and primes interior and exterior surfaces before you paint. Its powerful stain-blocking formula covers most heavy stains, bonds to a wide range of surfaces, and dries to the touch in 15–30 minutes, so you can topcoat in as little as 1 hour.
It's formulated to block water, smoke, nicotine, tannin, ink, pencil, felt marker and grease stains, from water-stained ceilings to smoke-damaged walls. These are the heavy stains that would otherwise bleed through standard paint.
Use it on new and repaired drywall and plaster, bare and previously painted wood, paneling and hardboard, wallpaper, masonry, brick, concrete, stucco, metal, vinyl siding, soffits, moulding and fascia. Scuff-sand glossy surfaces first for the best adhesion. It's not recommended for floors, decks, or surfaces that sit in water or get prolonged water contact.
Yes. Ceilings and interior walls are some of the most common places to use it. Make sure the stained area is clean and completely dry, then apply in thin, even coats from about 12 inches away.
Yes, it's designed for both. Indoors: use it in a well-ventilated area and keep the area clear of sparks, heat and open flame. Outdoors: don't apply it in rain, in humidity above 85%, or when rain is expected within 24 hours. Either way, wear safety glasses and chemical-resistant gloves, and apply between 50°F and 90°F.

It's dry to the touch in 15–30 minutes, and you can topcoat in as little as 1 hour. Allow 24 hours before heavy use.Times at 77°F and 50% relative humidity.
Latex (acrylic) or oil-based paint both work over it, after about 1 hour of drying time.
For best results, apply 2–3 thin coats instead of one heavy one. Hold the can about 12 inches away and sweep side to side, overlapping each pass by half.
One 12 oz can covers about 6–8 sq ft, enough to spot-prime most water, smoke and marker stains. For larger areas or 2–3 coats, plan on more than one can.
After each use, turn the can upside down and spray until only clear gas comes out. That clears the valve so it's ready next time. Clean any fresh overspray right away with mineral spirits or paint thinner.
Store it in a cool, dry place away from heat, sparks and open flame. Don't store it above 120°F or leave it in direct sunlight for long periods, since excessive heat or pressure can cause the can to burst.

Flex Seal Primers

Choose the Right Primer

A great paint job starts with the right prep. Compare our primers to find the right one for your project.

Flex Seal Stain Blocking Primer, white, 12 oz can

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Stain Blocking Primer

Buy Now
Best for

Walls, ceilings, wood & masonry

What it does

Seals water, smoke, tannin, ink and grease stains so they don't bleed through paint

Ready to paint

In 1 hour · dry to the touch in 15–30 min

Temperature

Apply between 50°F and 90°F

Color and size

White · 12 oz can

Coverage

6–8 sq ft per can

Use

Interior & exterior

Flex Seal Metal and Auto Primer, gray, 15 oz can

Also available

Metal & Auto Primer

Shop Metal & AutoShop Now
Best for

Cars, bare & coated metal

What it does

Inhibits rust and bonds to bare and coated metal

Ready to paint

In 10 minutes · sandable in 5 min

Temperature

Heat resistant to 250°F · apply 50–90°F

Color and size

Gray · 15 oz can

Coverage

18 sq ft per can

Use

Interior & exterior