The best paint to cover and block a stain - Decorator's forum UK (2025)

There are several different types of stain block on the market, each of which has attributes that suit different situations. In this blog, I’ll talk through the best paints to cover and block a stain based on my experience as a Decorator.

The Different Types of Stain Block Available

I thought I’d begin by taking you trough the different types of stain blocking products available and explain why you might use each of them. Further down the blog, I’ll choose the best stain block for each.

Water-based stain blocks – These tend to be quicker and easier to use than the other options, with less smell. They are more environmentally friendly too. The downside of using a water-based stain block is you may find it less effective on difficult stains such as water marks and grease.

Stain block and emulsion in one – These are innovative products designed to reduce the number of coats of paint needed to cover and block a stain. These can be quite effective, except on very difficult stains.

Oil-based stain blocks – These are probably the most effective stain blocks available, so you might use them on very difficult stains like water-damage and mould. The biggest downside is the smell, which can be quite overpowering in a confined space. Extended drying times can also be an issue.

Shellac Stain Blocks – I like using shellac. It’s too brittle to be used outside, but inside it is as good as any oil-based stain block. You can normally paint over shellac-based stain blocks in 45 minutes too.

The Best Water-Based Stain Block

Each of the main paint manufacturers have their own water-based stain block. These are quite simply labelled “stain block” and are by far the easiest option, however, a lot of them are not very good. The only one I have used that I really rate is the new Zinsser BIN Aqua.

Even though it’s water-based, Zinsser BIN Aqua is genuinely one of the best paints to cover and block a stain. You’ll find it easy to apply, blocks odour, has fantastic opacity, and you can paint over it again after 45 minutes.

I have tested this paint as a stain block extensively on grease, lipstick, red wine, nicotine, coffee, felt tip and water-damage. It isn’t very good on water damage and certain felt tips still bleed through, but for everything else it’s fantastic. I tend to apply two coats of Zinsser BIN Aqua 20 minutes apart, then wait an hour, then paint over with my topcoats. This is a really good product.

The Best Stain block and Finish Coat in One

As paint technology advances, “all-in-one” type stain blocks are starting to pop up. As a paint geek, I’m always chomping at the bit to test products like this as soon as they’re launched. There are two products on this section I’d like to talk about: one matt emulsion and one eggshell paint.

Johnstone’s StainAway

This is a durable matt emulsion that can also be used as a stain block. The important thing to remember if you’re using this paint is to adhere to the drying times, otherwise it will fail.

It isn’t the best paint to block water stains or other difficult marks, and it can ‘flash’ on large light-critical areas.

However, it works fantastically well on most stains, it’s very easy to use, has fantastic opacity, and you can get it mixed into any colour.

This was the first product of its type on the market. Some Decorators I know use it as a normal emulsion, simply because the opacity is so good. This is the best paint to use for covering light stains such as smoke damage or nicotine over large areas like whole ceilings or walls

Bradite One Can Eggshell

This is the other “all-in-one” product I wanted to mention. Bradite Once Can Eggshell can be used as an adhesion primer, stain block, and a finish coat. You could use it to paint your woodwork, or as an emulsion.

It’s a very good paint for blocking a stain. As with other water-based paints, I wouldn’t use it to tackle water damage or server marks, but it will work in most other cases. It’s very durable too, so perfect for painting a bathroom ceiling.

The Best 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 well ventilated. Otherwise, the fumes are a bit much.

Zinsser Cover Stain

You’ll find Cover Stain easy to use, available in different colours, and very good at blocking stains. The official recoat time is 2 hours, but I tend to dilute it with white spirit, apply two coats in quick succession, then wait 2 or 3 hours before applying my topcoats.

I like using Zinsser Cover Stain for blocking stains and odour. As a Professional Decorator, it’s a product I keep in the van and use often.

Oil-Based Undercoat

Genuinely the best paint to cover and block a stain. If oil-based undercoat doesn’t work, then nothing will. Undercoat is also readily available and cheap as chips.

Undercoat does stink when used over large areas, and you will need to wait 24 hours for it to cure properly before you can paint over with a water-based product. For this reason, I tend to stick to Cover Stain or one of the water-based products unless I’m dealing with a really bad stain.

The Best Shellac 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. It works just as well as oil-based undercoat.

Any shellac-based primer will do a job, but the best I have used is HB42 PS1 (Primer, Sealer, Stain Block). It has better opacity than the others, seems to take less coats, and is easier to use.

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.

Advertisement

FAQs

What is the best stain block for damp stains?

No stain block will stop water from coming into a room, so you need to fix the root of the problem before painting. But even when that’s done, there are not very many products capable of dealing with water stains.

My advice would be to stick with good old-fashioned oil-based undercoat, or a shellac-based primer. Avoid water-based stain blocks for this particular task.

How many coats of stain block do you need?

It depends on the nature of your stain and the product you’re using to cover it. One coat of stain block is often enough, but I always apply two anyway. I only do this because there is nothing worse than finishing a room, only to encounter problems further down the line.

Can I use PVA as a stain block?

No, you cannot use PVA as a stain block.

Will stain block stop mould?

Stain block will prevent the stains caused by mould from bleeding through your ‘finish coat’, but it won’t prevent mould from returning. For that, you may just need an anti-mould paint, or you may need to investigate why the mould is there.

Advertisement

Ryan Micheal Foulger

Professional Painter and Decorator

Mike Farrington

Professional Painter and Decorator

Jamie Wakeford

Professional Painter and Decorator

Rob Mitchel

Professional Painter and Decorator

Kevin Baird

Professional Painter and Decorator

Advertisement

Mike Johnstone

Professional Painter and Decorator

John Jones

Professional Painter and Decorator

Stephen Russell

Professional Painter and Decorator

Lee Robinson

Professional Painter and Decorator

Mandy Penman

Professional Painter and Decorator

John Sweeney

Professional Painter and Decorator

Vaughan Dibble

Professional Painter and Decorator

Advertisement

Clive Hamilton

Professional Painter and Decorator

Ian Haveron

Professional Painter and Decorator

Matthew James Rees

Professional Painter and Decorator

Fred Mercer

Professional Painter and Decorator

Kevin Shortman

Professional Painter and Decorator

Dave Molyneux

Professional Painter and Decorator

Alan Moloney

Professional Painter and Decorator