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The best paint to cover and block a stain

Updated Feb 10, 2023 | Posted Aug 28, 2019 | Product Advice, Professional insight | 11 comments

There are several different stain blocking products on the market which are all good in a different ways, or for blocking and covering up different types of stain. I’ll take you through the main paints in this blog, which will help you make the right choice. It is often cheaper to buy stain bloks online, so I’ll link to websites I use so you can find what you need.


Generic Waterbased stain blocks


Each of the main paint manufacturers have their own water-based version of stain block. These are quite simply labeled “stain block” and are by far the easiest option, however, may not be as effective on harder stains such as water-marks. This doesn’t mean they don’t have their uses; a ceiling which is affected by nicotine from cigarette smoke for example. Just don’t expect miracles, any heavy stains need to be dealt with by something a bit more robust.


Stain block and Finish Coat in One

As paint technology is advancing, we now have all these new “all-in-one” products that are really quite impressive.

Johnstone’s StainAway is a white, durable matt emulsion which blocks out stains quite affectively and leaves a nice finish, eliminating the need for more than one product. This paint works well on pretty much any type of stain, except maybe water marks. It is important to leave the first coat for at least 4 hours before applying your second. You should avoid using Johnstone’s StainAway on large open-plan ceilings as it can flash a little. You can buy this product online at PaintWell.

the best paint to block a stain

Another fine example of this is Zinsser Perma White. Again, it will block out mild stains, doubles up as an emulsion and has mold inhibitors, meaning it will combat mould and mildew growth in the future. It is the perfect product for a bathroom or kitchen.

The other advantage is Zinsser Perma White is durable enough to use on ceilings, walls and woodwork and it can also be tinted. Note, this product will not block a stain as effectively as some of the products listed below, but if you want longevity in a room susceptible to mold growth then this is the product for you. Click here to see online prices.


Oil-Based Stain Blocks


Now we are talking!! These products are the most effective at blocking and covering stains such as grease, water marks, heavy nicotine and graffiti. Just make sure if you are applying it inside over a large area, you keep your work area nice and ventilated. Otherwise the fumes are a bit much. Look out for Zinsser CoverStain, or any oil-based undercoat. I personally feel these work very well. You can buy coverstain from loads of trade outlets but unless you have a trade account it may be better to purchase it online. Click here to see online prices.

Some of the old-school decorators I know use pliolite-based masonry paint to block a stain. Whilst this type of product will work, I wouldn’t advise using it indoors. The fumes may be a little overwhelming and it can’t be healthy for you.


Shellac Based Stain Block


Shellac is a material made by beetles and used in both nail varnish and paint The beauty of using shellac-based primers to block a stain is the effectiveness and speed of which the product dries. There is probably no paint more capable than shellac to block any stain.


The best product of this type I have used is HB42 Primer Sealer, which is available online. You’ll find the opacity and ease of use better than most other shellac-based products. It will hold any type of stain back, and you can paint over it after around 40 minutes. Unlike other shellac, or oil-based primers, there is very little smell from it.

You will have problems washing your tools out afterwards, so I suggest using cheap painting equipment, then throwing it away after use. This product is for interior use only.


What do Other Decorators Ues to Block Stains?

I do like coverstain in a spray can for small areas. I’ve always got one in the van in case I have any stain bleeds. Shellac is good for larger stains like whole ceilings. Nothing is better than oil-based undercoat, but it can’t be healthy because of the fumes.

Ryan Micheal Foulger

The cheapest and best way to cover and block a stain has always been oil-based undercoat. All you need to do is loosen up the product with some white spirit, double roll, leave to cure and you’re good to go. Shellac-based paint is good, but it can lead to adhesion issues between stain block an emulsion if you’re not careful. You can’t use contract matt emulsion if you want to paint over shellac.

Mike Farrington

If drying time is an issue then use Zinsser BIN, however often it dries as an amber colour. If drying time isn’t an issue and you never want a call back for a stain then use oil undercoat, any will do. Never fails and dries white. Coo-Var also has a good product which is a stain block and finish in one. Perfect for a small ceiling. Johnstone’s Stainaway is good, however I have seen it fail a few times when people rush the recoat.

Jamie Wakeford

In my opinion, The best paint to cover and block a stain is oil-based undercoat. It’s just a shame about the drying time and paint fumes. PS1 primer is a great alternative, dries quick and doesn’t stink. That’s all I use now.

Rob Mitchel - The best paint to cover and block a stain


It depends on want the stain is. For water mark or if just a small stain, I normally use Zinsser Bin as it will block the stain and has a quick drying time. For large water stains, again a Zinsser product, coverstain primer sealer.

Alan Shorney

Smith and Rodger blockade for me. It’s like Zinsser BIN but better. I haven’t tried PS1 primer yet.

Stooie Walker

If you have the time to wait for your stain block to dry, then oil-based undercoat will beat any fancy Zinsser product.

Kevin Baird

Back in the day we used to use pliolite masonry paint to block a stain, but thinking back, I’ve no idea how we put up with the fumes!! It is horrible inside!! Absolutely kills stains though. Same with oil-based undercoat really, but that is still a good option.

Johnstone’s StainAway is a good product providing you leave a good 5 hours in between coats. For large areas I’ll either use Zinsser Coverstain or the PS1 Primer, which is also good.

Mike Johnstone

Why fix something that isn’t broke?? We have been using oil-based undercoat to block stains for years and it is still the best paint for the job. It is cheap, you can dilute it and it blocks stains better than anything else on the market.

Just loosen the paint a little with white spirits, then double roll. Providing there isn’t an active water leak, it will work every time. You need to let undercoat dry over-night before you paint over it.

John Jones

I’d give the stain a good coat of oil-based undercoat. Allow plenty of drying time before giving it a coat of Armstead pure brilliant white emulsion. Again, give it time to dry and see if the stain comes back. If it doesn’t, go ahead and final coat it in your chosen paint. if the stain does come back, source where it’s coming from and solve the issue, then repeat the process to cover the stain.

Stephen Russell

I find that oil-based undercoat is the best paint to block a stain. As a decorator, if I get the job, then I arrange to go round a few times in the evenings to apply multiple coats of undercoat. Then when I start the job, if the stain has come through again, I know that the source of the stain is still active. Maybe the client has water leaking into their house, or maybe there is a different problem that needs sorting before I can paint.

I find that once applied, oil-based undercoat covers well with the first coat of emulsion and then I have total piece of mind before the final coat. Sometimes with Coverstain and shellac I find there is a shiny patch that worries me.

Lee Robinson

Blockade beats Zinsser BIN to block a stain. Great product and easier to apply.

Mandy Penman

I’ve always used Coverstain and it never fails, great stain blocker 👍

John Sweeney

Crown PX4 is the best paint to block and cover a stain…1 hour, job done. No stains will ever get through.

Vaughan Dibble


Oil-based undercoat usually does the trick when blocking stains is time isn’t an issue. I tend to carry a spray can of polycell stain block for occasional water stains. It’s just easier and it dries in 30mins. Much better than the Zinsser alternative which gets clogging issues after the first use.

Clive Hamilton

Oil based undercoat is the best paint to cover and block a stain for me. Yes, takes longer to dry, but for larger areas it’s a cheaper and more effective than the Zinsser products. Undercoat also doesn’t flash/shine through the emulsion. Pliolite is another good alternative, these products are also great over smoke/nicotine.

Ian Haveron

I always use one Cover Stain then one coat of 123plus on any nasty stains. Only because emulsion will sit on the Cover Stain and take ages to dry.

Matthew James Rees

PS1 for me. It’s a fantastic primer for blocking stains.

Fred Mercer

Just use oil-based undercoat. That’s how we did it years ago and it still works better than any of these water-based stain block products.

Kevin Shortman

Zinsser Cover Stain or B.I.N for stain blocking👍

Dave Molyneux Professional Decorator

Zinsser Cover Stain


Johnstone’s StainAway

Alan Moloney

Crown Satin is a great stain block if you can wait for drying.

Pete Meadows

For me Zinsser Cover Stain is the best. I know you can use oil undercoat, but why wait 16 hours to recoat when you can do it after one hour.

Daniel James Wilson


Zinsser Cover Stain, which I always have it in the van. I get a lot of damp and grease stains to deal with, and Cover Stain always does the job.

Rob Taylor

Fossa Primeout works most of the time for me. But Johnstone’s Damp Proof paint is also a very good stain blocker and goes on slightly better.

Sean Danes

Zinsser Cover Stain is the best paint to block a stain. It dries quickly and can be recoated in 2 hours. It is as good as oil-based undercoat.

Paddy Cooper

Apply a coat of oil-based undercoat first thing in the morning and then you’re done.

Updated Feb 10, 2023 | Posted Aug 28, 2019 | 11 comments

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  1. Ms Doreen Elcox

    There are shiny caulking stains (the caulking was used to stick down paper edges) on newly painted, papered walls. The paint is dark mustard-coloured emulsion. Further coats of paint have not covered them.
    Can you recommend a cover that I can just paint over.

    • Mike Cupit

      You could use coverstain, oil-based undercoat or zinsser bin

      • Tracey Sharp

        I’ve got a job to do – I am not a professional – part of the ceiling and walls have soot stains from a previous fire. I know that not matter how I clean this it will leach through the emulsion – what’s the best stain block to use please??

  2. Casey

    What is the best Stain block for soot after fire damage…ceilings mainly

  3. Stuart Hart

    Dear Decorators forum UK,

    The word in UK English is mould.

    • Chels

      Gold medal for you!

  4. Sandra

    i would like to find a stain block that doesn’t have a strong smell and suitable for use in homes with people sensitive to smells or have breathing problems.

    • Mike Cupit

      Try Johnstone’s Trade StainAway

  5. Joe

    Hi all

    Just wondering you could help is there any type of paint or type of pva that will work over water repellent.


  6. Ellie D

    Hi, We have a few persistent spots in our bathrooms where condensation keeps coming through. What’s the best produce to use to stop it being visible and is it as easy as painting on top of what’s there or is there prep work in the areas needed first?

  7. John Rose

    Jow many professional decorators go back and look at their work after a few years. A couple of coats of a hood oil based white gloss…plenty of opacity and good film forming properties impervious to water based stain bleed always works for me.


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