The Best Stain Block Paints For Water Stains, Damp And Smoke
Six primers and sealers we'd trust to stop leak marks and old damp patches bleeding back through fresh emulsion.
Our quick verdict
Our pick of the best stain block paint is the Zinsser Cover Stain Primer. It sealed the grey and brown water marks on our ceiling, and with a 2 hour recoat you can prime and emulsion a room in the same day. If you've only got one or two small marks, the Everbuild Stain Block Paint aerosol saves getting a tin and roller out.
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Our Picks At A Glance
- Check price of Zinsser Cover Stain Primer
Best Overall
Zinsser Cover Stain PrimerWater, smoke and nicotine stains on ceilings and walls inside or out
- Check price of Everbuild Stain Block Paint
Best Aerosol
Everbuild Stain Block PaintSmall marks and patches where getting a tin and roller out is overkill
- Check price of Rustins Stain Blocker Paint
Most Versatile
Rustins Stain Blocker PaintMixed surfaces such as wood, plaster and painted walls indoors or out
- Check price of Ronseal One Coat Damp Seal
Best For Damp Walls
Ronseal One Coat Damp SealInterior walls and ceilings marked by damp that has been fixed
- Check price of Leyland Stain Blocking Primer
Best Heavy Duty
Leyland Stain Blocking PrimerLarge areas with tough stains such as nicotine, marker pen or graffiti
- Check price of Polycell Stain Stop
Best Value Runner-Up
Polycell Stain StopEveryday water stains on plaster, plasterboard, masonry and wood indoors
Smell is the trade-off that decides most of this list. Solvent-based primers seal heavy water and smoke marks best but fill a room with fumes, while water-based blockers are kinder to live with and can need extra coats on a dark mark. Job size settles the rest, as a spray can is quick on a hand-sized patch and slow across a ceiling.
We've used stain blockers on our own homes and the rentals we look after, and the six here run from a small aerosol to a 2.5 litre tin for whole rooms.
How We Tested These Stain Block Paints
Stain blockers have been part of our kit for years, on everything from water stains left by a leaking roof to damp patches that had been put right. One recent job was a ceiling with grey and brown water marks across it. Zinsser Cover Stain Primer, the tin shown below, went on that one, and it was as simple to apply as any ordinary paint.
Before committing to the whole ceiling, we put a single coat on the middle stain as a test and left it to see whether the mark came back through. It didn't, so we rolled the stain blocker over the full ceiling, let it dry and finished with a white emulsion for ceilings. The two photos below show the water marks on that ceiling.
We filmed part of the Zinsser job for our YouTube channel, so you can see how the primer rolls out over a marked ceiling.
Need To Tackle Stains? Look No Further Than Stain Blocking Paint & We've Been Testing Multiple!
Several of the other paints in this list have been through our hands too, and each one was judged on the same points:
- Effectiveness: whether the stain stays hidden once emulsion goes over the top
- Application: how easily it goes on
- Coverage: how far a tin goes
- Finish: how it looks and takes a topcoat
- Drying: how soon it can be recoated or painted over
- Versatility: the stains and surfaces it suits
- Value: the tin sizes on offer and the price per litre
Where we haven't measured something ourselves, such as coverage per litre or drying times, the figures come from the manufacturer and we say so.
The Best Stain Block Paints We Recommend
All six seal the common household stains so a normal emulsion can go over the top. The notes on coats and drying come from our own jobs where we have them.
Best Overall
Zinsser Cover Stain Primer
Best for: Water, smoke and nicotine stains on ceilings and walls inside or out
Check Price On AmazonZinsser Cover Stain is the primer we used on the leak-damaged ceiling in our testing photos, and it's the one we've had the best results from on water, smoke and nicotine stains. One coat over the test patch was enough to stop the mark coming back, and over the years we've only needed a second coat on the odd occasion.
The tin we bought says it dries in 30 minutes and can be recoated in 2 hours, so you can prime in the morning and get emulsion on later the same day. It cleans up with paint thinner rather than water, so keep a jar of white spirit handy for the roller. It also grips glossy surfaces without sanding, Zinsser says, so you can go straight over old gloss or silk as well as bare plaster, and the brand quotes up to 9.8 square metres from a litre.
What we like
- One coat on our test stain and it never reappeared
- Recoat in 2 hours according to the tin
- Works on smoke and nicotine as well as water marks
- Up to 9.8 square metres per litre according to Zinsser
- Grips glossy surfaces without sanding according to the brand
- Suitable for interior and exterior use
What to know
- A few heavy stains have needed a second coat on our jobs
- Brushes and rollers need paint thinner to clean
Our verdict
A ceiling or wall with mixed marks that you want sealed and painted in a day is the ideal job for Zinsser Cover Stain. It's our first choice for leak damage, and you won't lose a day waiting for it to dry. The drawback is clean-up, as rollers and brushes need paint thinner. For a damp patch that hasn't fully dried, Ronseal One Coat Damp Seal is built for the job.
Best Aerosol
Everbuild Stain Block Paint
Best for: Small marks and patches where getting a tin and roller out is overkill
Check Price On AmazonEverbuild Stain Block comes in an aerosol, so it suits a single water ring on a ceiling or a few pen marks on a wall. There's no tin to open and no roller to wash afterwards, and it's one of the cheapest stain blockers in this list.
Everbuild says it works on water marks, mould staining, nicotine and grease, and that it's dry in 15 minutes. When we used it, the smell was very strong while spraying, so open the windows and give the room time to clear. Overspray is the other thing to plan for. We masked off the surrounding surfaces before spraying, and a decent decorator's masking tape and a dust sheet will save you cleaning specks off the walls and floor.
What we like
- Sprays straight from the can with no brushes to clean
- Among the cheapest stain blockers we recommend
- Dry in 15 minutes according to Everbuild
- Covers water marks, nicotine, grease and mould staining
What to know
- Very strong smell while spraying in our use
- Overspray means masking off the area first
Our verdict
Buy the Everbuild aerosol for one or two small stains where speed matters more than coverage. It's not the one for a whole ceiling, as an aerosol works out dear over a big area and the smell builds up. For larger jobs, a tin of Zinsser Cover Stain or Polycell Stain Stop makes more sense.
Most Versatile
Rustins Stain Blocker Paint
Best for: Mixed surfaces such as wood, plaster and painted walls indoors or out
Check Price On AmazonRustins Stain Blocker is a water-based matt primer, which makes it one of the easiest paints here to live with in an occupied house. The smell is low, it dries quickly and brushes wash out under the tap. Rustins says it sticks to wood, plaster and previously painted surfaces, inside or outside.
The trade-off showed up on a dark water stain, where we needed three coats before the mark stopped showing through. Lighter stains need fewer, but if you're dealing with a heavy brown tide mark, factor in the extra coats and drying time. It's sold in 250ml, 500ml and 1 litre tins, so you can buy the size that fits the job and avoid a half-full tin sitting in the shed.
What we like
- Low smell while painting
- Water based so brushes rinse clean
- Sticks to wood, plaster and old paint according to Rustins
- For indoor and outdoor surfaces
- Sold in 250ml, 500ml and 1 litre tins
What to know
- Took three coats to hide a dark water stain on our job
Our verdict
Choose Rustins if you want a low-odour stain blocker for an occupied home, or one tin that covers a skirting, a door and a patch of wall. Be ready to add coats on dark marks. If you'd rather seal a heavy stain in one go, Zinsser Cover Stain did that on our ceiling.
Best For Damp Walls
Ronseal One Coat Damp Seal
Best for: Interior walls and ceilings marked by damp that has been fixed
Check Price On AmazonRonseal One Coat Damp Seal is built for damp patches, and it's the one stain blocker in this list you can paint straight onto a damp wall or ceiling. Ronseal says it blocks damp stains permanently in a single coat, needs no preparation, and lets trapped moisture escape so the topcoat doesn't flake and peel. Our round-up of anti-mould paints for damp rooms covers the paint side of a damp problem.
Ronseal says it's touch dry in 2 hours and ready for a topcoat after 4, so a morning coat can take emulsion the same afternoon. A litre only stretches to around 5 square metres, though, so a big ceiling gets expensive, and the smell is strong while you work. It's for interior use only. Remember it hides the mark rather than curing the cause, so find and fix the leak or condensation problem first.
What we like
- Goes straight onto damp walls and ceilings
- Single coat according to Ronseal
- Lets trapped moisture out to stop the topcoat peeling
- Topcoat after 4 hours according to Ronseal
- No preparation needed before painting
What to know
- Around 5 square metres per litre makes it dear to cover a large area
- Interior use only
- Strong smell during application
Our verdict
Buy Ronseal Damp Seal for a patch that's still damp after the cause has been fixed, as nothing else in this list is made to go onto a damp surface. Low coverage makes it dear over big areas and you'll want the windows open. On dry water stains, Zinsser Cover Stain or Polycell Stain Stop does the job.
Best Heavy Duty
Leyland Stain Blocking Primer
Best for: Large areas with tough stains such as nicotine, marker pen or graffiti
Check Price On AmazonLeyland's Stain Blocking Primer is aimed at the stubborn stains, and Leyland lists nicotine, graffiti and marker pen among the marks it locks in. Once it's dry, emulsion goes straight over the top without the stain bleeding through. It rolls or brushes on easily and dries to a hard matt finish.
It comes in a 2.5 litre tin only, which suits whole rooms rather than a single patch. That's useful when you're redecorating a rental after a smoker has moved out, and Leyland quotes about 8 square metres per litre, so one tin goes a long way. Recoating takes 2 to 4 hours according to the brand. For a single mark on a ceiling, most of the tin would end up wasted.
What we like
- Made for nicotine, graffiti and marker pen
- Around 8 square metres per litre according to Leyland
- Brush or roller application
- Good price per litre in the larger tin
- Recoat in 2 to 4 hours according to Leyland
- Dries to a hard matt finish
What to know
- Only sold in a 2.5 litre tin, too much for small patches
Our verdict
The Leyland primer earns its place when the staining runs across whole rooms, such as a smoker's flat being turned round between tenants, where the 2.5 litre tin and good price per litre pay off. For one or two small marks, that tin is far too much, and the Rustins 250ml tin or the Everbuild aerosol is a better buy.
Best Value Runner-Up
Polycell Stain Stop
Best for: Everyday water stains on plaster, plasterboard, masonry and wood indoors
Check Price On AmazonPolycell Stain Stop is an affordable stain blocker from a brand most DIYers will know, and it covers most household stains on plaster, plasterboard, stone, masonry and wood. We used it on a water stain and it blocked the mark well, with a single coat doing the job.
The smell is low and it goes on easily, so it's a good one for a bedroom or landing you need back in use. Patience is the catch. Polycell says it's surface dry in 2 to 3 hours, but you need to wait up to 12 hours before a second coat. It's for interior use only, and if you prefer to spray, Polycell also sells it as an aerosol.
What we like
- Blocked a water stain well on our job
- One coat for most stains according to Polycell
- Low smell during application
- Works on plaster, plasterboard, masonry and wood
- Also sold as an aerosol
What to know
- Up to 12 hours before a second coat according to Polycell
- Interior surfaces only
Our verdict
Polycell Stain Stop is a good buy for a dry water stain or two when you're not in a rush. It keeps the cost down without cutting corners on the seal. If you need the room finished the same day, Zinsser's 2 hour recoat time is the better fit, and damp walls belong with Ronseal Damp Seal.
Choosing A Stain Block Paint For Your Job
The right stain blocker depends on what caused the mark, how big the area is and whether the surface is still damp. Work through these questions before buying.
Fix The Cause Before You Seal The Stain
A stain blocker hides the mark, but it won't stop a leak, rising damp or condensation. If the stain is from a roof leak, a dripping pipe or a shower tray, sort the water source first and let the area dry out properly. Painting over an active leak just means the stain returns, and the plaster underneath carries on getting wet.
Black spots are a different problem. Mould needs killing and cleaning off before any paint goes on, and our guide on how to get rid of mould on walls and ceilings covers the steps. Once it's clean and dry, a stain blocker will cover any shadow it leaves behind.
Solvent Based Or Water Based
Solvent-based primers such as Zinsser Cover Stain give a strong seal on heavy water and smoke marks, but they smell and you'll need white spirit to clean up. Water-based options like Rustins are far nicer to use in a home you're living in, though dark stains can take extra coats. For a ceiling that's badly marked, we'd put up with the smell. For a light mark in a child's bedroom, water based makes more sense.
Damp Surfaces Need A Damp Seal
Most stain blockers need a dry surface to bond properly. If a wall or ceiling is still slightly damp, or the patch is in a spot that never fully dries, a damp seal such as Ronseal One Coat Damp Seal is the safer choice because it's made to go onto damp surfaces. Peeling paint around a damp patch in a bathroom is a sign of trapped moisture, and our guide on why bathroom ceiling paint peels explains what's going on.
Aerosol Or Tin
An aerosol is quick for a mark the size of your hand, with no brush to wash out afterwards. Over a whole ceiling, though, it's slower, smellier and dearer than a tin. Spray needs masking around it too. For anything bigger than a couple of small patches, buy a tin and use a roller, and pick a decent one from our tested paint rollers so the primer goes on evenly.
Tin Size And Coverage
Check the coverage figure on the tin against the area you're painting, and remember a dark stain can take more than one coat. A 250ml tin is plenty for a few patches, while a whole room of nicotine staining needs a 2.5 litre tin. Coverage drops on rough or porous surfaces, so if you're priming bare or patched plaster, allow for it soaking up more than the label suggests.
Stain Block Questions From Homeowners
Do you need to paint the whole ceiling with stain block?
No, you can spot prime just the stained areas with stain block paint and then emulsion the whole ceiling. The catch is that primer can leave a slight difference in sheen or texture, which shows through on a ceiling lit from a window. On our leak-damaged ceiling we tested one patch first, then primed the whole surface so the emulsion went on evenly.
How many coats of stain block paint do you need?
One coat seals most stains when you use a solvent-based primer like Zinsser Cover Stain. Dark water marks and heavy nicotine can need two, and water-based stain blockers take more on dark stains, as Rustins needed three coats on one of ours. Let the first coat dry, check for any shadow coming through, then add another before the emulsion.
Can you use normal emulsion over stain block paint?
Yes, stain block paint is designed to be painted over with a normal emulsion once it's dry. Check the tin for the recoat time, which varies from 2 hours for Zinsser Cover Stain to around 12 hours for Polycell Stain Stop. Two coats of emulsion over the primer give the most even colour, especially on a ceiling.
Why do water stains come back through emulsion?
Water stains come back because the leak leaves minerals and tannins in the plaster, and fresh emulsion is water based, so it draws those marks back up to the surface as it dries. A stain blocker forms a sealed layer between the stain and the topcoat, which stops the mark bleeding through. Fix the leak first or the stain will keep returning.
Can a stain blocker fix a damp wall?
No, a stain blocker hides the mark but it won't stop a leak, rising damp or condensation, so sort the water source first. Once the cause is fixed, Ronseal One Coat Damp Seal is the one made for damp patches, because it goes straight onto a damp wall or ceiling and lets trapped moisture escape so the topcoat doesn't peel.
Is Zinsser Cover Stain worth the clean-up?
Yes, because it sealed our test stain in one coat and the mark never reappeared. The tin says it recoats in 2 hours, so you can prime and paint a ceiling in a day. The drawback is that brushes and rollers need paint thinner to clean, so use a cheap roller sleeve you can throw away. A few heavy stains have needed a second coat on our jobs.
Is the Everbuild stain block aerosol any good for a small mark?
It suits one or two small marks, such as a single water ring on a ceiling. Everbuild says it's dry in 15 minutes and there's no tin to open or roller to wash. The smell was very strong while spraying when we used it, and overspray means masking off the area first. For a whole ceiling, a tin of Zinsser Cover Stain makes more sense.
Is Rustins Stain Blocker strong enough for dark water stains?
On a dark water stain it took us three coats before the mark stopped showing through, so it isn't the quick option for heavy marks. Rustins is a water-based matt primer with a low smell and brushes rinse clean under the tap, which suits an occupied home. Zinsser Cover Stain sealed the stained ceiling in our testing in one coat.
Our Pick For Sealing Stains
Zinsser Cover Stain Primer is the stain blocker we'd buy for most jobs. It sealed the water marks on our ceiling in one coat and can be painted over after a couple of hours. For walls or ceilings that are still damp, Ronseal One Coat Damp Seal is the one to use instead.
On a smaller budget, Polycell Stain Stop gives a solid result if you can wait for it to dry, and the Everbuild aerosol is the quick fix for one small mark.
Eddie spent five years as a self-employed painter and decorator before going part time to become one of the main writers at DIY Works. From garden fences to mist coats on fresh plaster, painting and decorating is his speciality.