The best wood primers, compared.
Top pick: Berger wood primer 750 ml Best value: Johnstone's primer undercoat 750 ml – About £9.92 for 750 ml of water-based primer undercoat named for wood and metal, the lower 750 ml shelf price in this set. Updated October 2026.
A wood primer, or a combined primer and undercoat, is the first coat on bare or stripped timber so that gloss, satin or eggshell does not sink in unevenly. The amazon.co.uk tins are decorating primers for doors, windows, skirting and radiators, not artist gesso or touch-up pens. This wood primer comparison lines up six listings. The 6,050 figure on the three larger sizes is a shared parent line, not three separate tests. How to separate primer, undercoat, knot block and preservative is in the [wood primer buying guide](/hub/paints-and-varnishes/wood-primer/sub/wood-primer-buying-guide). An undercoat builds a level base for gloss, satin or eggshell. Knotting, or a knot-block primer, is a spot coat for knots and sap. A tannin-blocking primer is for oak and similar hardwoods under pale colours. A preservative primer is a biocidal first coat for exterior softwood, and it is a different product from these white decorating tins.
A wood primer, or a combined primer and undercoat, is the first coat on bare or stripped timber so that gloss, satin or eggshell does not sink in unevenly.
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Personal buying guide
Question 1 of 2
What are you priming?
Berger Wood Primer is listed at £11.04 for 750 ml white, with a matte finish and a surface recommendation of wood. Coverage is stated as 10 to 12 m² per litre. Weight is 1 kg. The paint-type line says oil-based or water-based, so the binder is not identified. The rating line is 5.0 from 1 review, and the saved listing contains no review text. Rank is 260,577 in DIY & Tools and 408 in Primer. Waterproof is false and water resistance is water resistant. Model number and part number are given as does not apply. Dry time, country of origin and whether a topcoat is required are not in the saved listing.
Pros
Cons
Best for: A 750 ml white wood primer only if you can confirm the binder on the tin, because the listing does not.
Less suitable: A decision that depends on UK review evidence. There is none in the saved listing.
Specifications
Common questions
Is Berger wood primer water-based?
The paint-type line says oil-based or water-based. The saved listing does not choose one.
What do UK reviewers say?
The listing shows 5.0 from 1 review. The saved listing has no review text.
What coverage is stated?
10 to 12 m² per litre, on a 750 ml pack.
The amazon.co.uk listing prices this 750 ml brilliant white Johnstone's primer undercoat at £9.92. The paint-type line is water-based, the surface line is wood and metal, and the rating line is 4.6 from 6,050 reviews. That 6,050 figure is repeated on the 1.25 litre and 2.5 litre ASINs with the same opening reviews, so it is a shared parent count. Bullets say dry to the touch in 1 to 2 hours and 13 m² per tin. The dry-time attribute says 15 hours and the indoor-outdoor attribute says indoor. UK reviews praise doors, window frames and radiators, and also report fast drying that is hard to brush, brittle chips off new timber, and a smell that needed ventilation.
Pros
Cons
Best for: A 750 ml water-based primer undercoat for interior wood or metal when the lower shelf price matters more than a wood-only title.
Less suitable: Anyone who needs a single dry time. The attribute says 15 hours and the bullets say 1 to 2 hours.
Specifications
Common questions
Is the 750 ml Johnstone's tin water-based?
The paint-type attribute says water-based. UK reviews mention cleaning brushes with water.
Can the listing be used on metal?
The title and the surface recommendation both name metal. UK reviews mention radiators taken back to bare metal.
How fast does this listing say it dries?
The bullets say dry to the touch in 1 to 2 hours. The dry-time attribute says 15 hours, and the full-cure attribute says 2 hours.
The 2.5 litre brilliant white tin is listed at £23.99. Weight is 3.75 kg and the country of origin is the United Kingdom. The paint-type attribute says Primer, while the bullets say the formula is water-based. Coverage is written as 13 m² per tin, the same phrase used on the 750 ml listing. Dry time is 0.5 hours and full cure is 24 hours. The surface recommendation is wood and masonry, while the title says wood and metal. The indoor attribute says indoor. The rating line is again 4.6 from 6,050 with the same opening UK reviews. At the listed price this is about £9.60 per litre, the lowest litre price in the kept set.
Pros
Cons
Best for: Several doors or a run of joinery when you can buy 2.5 litres at £23.99 and you do not rely on the 13 m² per tin line.
Less suitable: A small touch-up. A 250 ml or 750 ml tin wastes less paint.
Specifications
Common questions
What is the listed price for 2.5 litres?
£23.99 on the amazon.co.uk listing, about £9.60 per litre at that shelf price.
What coverage is printed?
13 m² per tin. The same bullet appears on the smaller Johnstone's sizes.
Does the surface line match the title?
The title says wood and metal. The surface recommendation on this ASIN says wood and masonry.
This 1.25 litre brilliant white tin is listed at £14.51 on amazon.co.uk. The paint type is water-based, the country of origin is the United Kingdom, and the finish attribute says gloss. The rating line is again 4.6 from 6,050, with the same opening UK reviews as the 750 ml ASIN. The coverage attribute reads about 1.25 m² per litre, while the bullets still say 13 m² per tin. The dry-time and full-cure attributes are both 2 hours. The indoor-outdoor attribute says indoor, and the waterproof flag is false while water resistance says water resistant. Weight is 1.5 kg.
Pros
Cons
Best for: A mid-size water-based tin when 750 ml is tight and you can ignore the 1.25 m² per litre coverage attribute.
Less suitable: A coverage calculation. The attribute and the bullet do not describe the same area.
Specifications
Common questions
What coverage does the 1.25 litre listing give?
The coverage attribute says about 1.25 m² per litre. The bullets say 13 m² per tin.
Is the country of origin stated?
Yes. The listing says United Kingdom.
Does this ASIN have its own 6,050 reviews?
The rating line says 4.6 from 6,050, and the first 50 reviews match the 750 ml saved listing.
The amazon.co.uk listing prices this white acrylic wood primer and undercoat at £17.24 for 750 ml, rated 4.6 from 1,944 reviews. Coverage is stated as 12 m² per 750 ml per coat, and the dry-time and full-cure attributes are both 2 hours. The surface line is wood, and the indoor-outdoor attribute says outdoor. UK reviews mention a new external timber door, new stairs, kitchen wood and water clean-up. The same reviews also mention a strong smell with a thin coat, a damaged tin that leaked, and yellow-brown bleed from the wood. The weight attribute is 408 g, which is light for a 750 ml tin of liquid paint.
Pros
Cons
Best for: Interior or exterior bare wood when you want a wood-only primer and undercoat with its own amazon.co.uk review record.
Less suitable: A knotty or tannin-rich timber if you need a stated knot block. The listing does not mention knots, and one UK review saw yellow-brown bleed.
Specifications
Common questions
Is this Dulux tin for wood?
The title and the surface recommendation both say wood. The listing does not name metal.
How long does the listing say it takes to dry?
The dry-time attribute and the full-cure attribute are both 2 hours.
What coverage does the listing state?
12 m² per 750 ml per coat. One UK reviewer said a 750 ml tin was about enough for one external door.
This 250 ml white tin is listed at £9.56, rated 4.4 from 107 amazon.co.uk reviews, which is a different count from the 6,050 on the larger Johnstone's ASINs. The paint type is water-based, weight is 410 g, and the country of origin is the United Kingdom. The coverage attribute says 3 m², while the bullets still say 13 m² per tin. Dry time is 1.5 hours. The indoor-outdoor attribute says outdoor, and the waterproof flag is true while water resistance says not water resistant. Rank is 42 in Primer, not 5. UK reviews praise quick drying and water clean-up, and complain that the tin is small, thin and, in one case, spilled.
Pros
Cons
Best for: A small interior or exterior wood or metal patch when 250 ml is enough.
Less suitable: A door. UK reviewers say the tin is smaller than they expected, and the 750 ml listing is 36p more.
Specifications
Common questions
How many reviews does the 250 ml tin show?
4.4 from 107. That is not the 6,050 count on the larger Johnstone's listings.
What coverage is on the attribute line?
3 m². The bullets still say 13 m² per tin.
Did UK reviewers mention the size?
Yes. Reviews say the tin was smaller than expected, and one compared 250 ml unfavourably with a cheaper 750 ml tin.
We compared six amazon.co.uk wood primer listings kept after category fit. Shelf prices, stars and review counts are the UK lines from 16 October 2026. Each score is an editorial 0–100 figure from those stars, damped when the review count is shared across sizes or is a single rating, and cut for listing conflicts and faults in the UK reviews. Price sets the best value badge. It does not set the score. There was no laboratory test.
Amazon stars
35%The star line on that amazon.co.uk listing. A high star with almost no reviews is damped.
Reviews on that size
30%A count that belongs to the ASIN scores higher. A parent count shared across sizes is damped.
Listing consistency
25%Coverage, dry time and weight that agree with the pack. A clash, or a fault in the UK reviews, cuts the score.
Base and surfaces
10%Whether the listing identifies the base and the surfaces. An oil-or-water line does not identify a clean-up method.
A wood primer is the first coat on bare or stripped timber. On these six amazon.co.uk listings it is usually a combined primer and undercoat in white or brilliant white. Read the base, the surfaces, and whether the coverage line and the review count belong to that tin. None of the listings says it blocks knots, and none is a wood preservative. Prices below are the shelf lines from 16 October 2026, not a laboratory test.
A primer seals bare wood so the finish does not sink in unevenly. An undercoat builds a level base for gloss, satin or eggshell. A primer undercoat is the combined tin Dulux and Johnstone's sell. Knotting, or a knot-block primer, is a spot coat for knots and sap. A tannin-blocking primer is for oak and similar hardwoods under pale colours. A preservative primer is a biocidal first coat for exterior softwood, and it is a different product from these white decorating tins.
A white primer undercoat is not a knot block unless it says so. None of these six listings says so. Dulux Trade's quick-dry sheet still says to knot first, and one Dulux UK review describes yellow-brown bleed.
Rustins shellac knotting is not for direct use under water-based paint. The identified tins here are water-based or acrylic. Berger's line says oil-based or water-based, so that listing does not tell you which clean-up to use.
The 750 ml, 1.25 litre and 2.5 litre Johnstone's listings all show 4.6 from 6,050 and the same first 50 UK reviews. Dulux is 4.6 from 1,944 on its own ASIN. Johnstone's 250 ml is 4.4 from 107. Berger is 5.0 from 1, with no review text.
The first split is the job. Bare wood needs a primer or a primer undercoat the topcoat maker accepts. Sound painted wood usually needs a key and an undercoat, with primer only on bare patches. Identified tins in this set are water-based or acrylic. Berger's paint-type line says oil-based or water-based, so you cannot choose a clean-up method from that page. Johnstone's titles say wood and metal. The 2.5 litre surface recommendation says wood and masonry, while the title says wood and metal.
Dulux states 12 m² per 750 ml per coat, and the dry-time and full-cure attributes are both 2 hours. That coverage matches the brand's up to 16 m² per litre. The weight attribute is 408 g, which is light for a 750 ml tin, so read the tin weight if the parcel arrives short. Johnstone's bullets say 13 m² per tin on every size. The 750 ml dry-time attribute says 15 hours and the bullets say 1 to 2 hours.
Three typical situations, each with a recommendation from this comparison.
You are priming bare wood and you want the review count that belongs to this tin. The Dulux wood primer and undercoat is about £17.24 for 750 ml, with 4.6 from 1,944 reviews. The surface line is wood. It does not say it blocks knots.
You want a 750 ml water-based primer undercoat for wood or metal, and the shelf price matters. Johnstone's 750 ml is about £9.92. The 4.6 from 6,050 line is shared with the larger sizes. The dry-time lines do not agree.
You can use 2.5 litres and you will not treat 13 m² per tin as the coverage estimate. Johnstone's 2.5 litre is about £23.99, about £9.60 per litre at that shelf price, the lowest litre price in this set. The review count is the shared 6,050 line.
The top pick is the Dulux wood primer and undercoat, 750 ml, at about £17.24. It is 4.6 from 1,944 reviews on that ASIN, with a coverage line of 12 m² per 750 ml per coat that matches the brand's up to 16 m² per litre. The best value is Johnstone's 750 ml primer undercoat at about £9.92, for wood or metal, with the shared 6,050-review line and a dry-time clash. None of the six listings says it stops knots or tannin, and none is a wood preservative.
Johnstone's primer undercoat 750 ml
About £9.92 for 750 ml of water-based primer undercoat named for wood and metal, the lower 750 ml shelf price in this set.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources used for the VOC, lead-paint and preparation points on this page. Prices, stars and review counts are from the amazon.co.uk listings on 16 October 2026.
This page contains affiliate links to amazon.co.uk with the tag pcuk26-21. If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are the UK listing lines from 16 October 2026. We did not run a lab test.
