Varnish vs polyurethane: which finish should you choose?
Updated: October 2026
You are standing in front of a bare interior door, table or floor and wondering whether to apply varnish first, then add polyurethane. The short answer is no: polyurethane is one type of varnish resin, not a compulsory second coating. Your choice is between finish systems suited to different jobs. The small acrylic bottles in our [synthetic varnish comparison](/hub/paints-and-varnishes/synthetic-varnish) are intended mainly for paintings and crafts; they are not substitutes for a joinery or floor-varnish tin. Understanding that distinction prevents an expensive mismatch before you start.
You are standing in front of a bare interior door, table or floor and wondering whether to apply varnish first, then add polyurethane.
You are standing in front of a bare interior door, table or floor and wondering whether to apply varnish first, then add polyurethane. The short answer is no: polyurethane is one type of varnish resin, not a compulsory second coating. Your choice is between finish systems suited to different jobs. The small acrylic bottles in our synthetic varnish comparison are intended mainly for paintings and crafts; they are not substitutes for a joinery or floor-varnish tin. Understanding that distinction prevents an expensive mismatch before you start.
Our top picks
| Badge | Product | Binder as listed | Finish | Two-pack | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Liquitex Liquitex Professional satin | Acrylic | Satin | No | 9.0 | about £14.93 | View offer |
| Alternative |  EIGTWEN EIGTWEN gloss and matte | Acrylic | Gloss and matte | No | 7.8 | about £14.36 | View offer |
| Best value |  Baker Ross Baker Ross FE585 gloss | Water-based | Gloss | No | 8.8 | about £8.99 | View offer |
On this page
Varnish is the film; polyurethane is one resin
“Varnish” describes a transparent protective finish rather than one fixed chemical recipe. The dried film may use polyurethane, alkyd, acrylic or a blend as its binder. A product labelled polyurethane varnish is therefore already a varnish: putting it over an unrelated varnish does not automatically create a tougher system.
Coo-Var markets its polyurethane varnish for worktops, floors and internal doors, but that is a stated use rather than independent evidence that it outperforms every alternative.
If your actual job is protecting an acrylic painting, the distinction changes. None of the retained UK listings describes itself as polyurethane. For help deciding whether that smaller format matches your project, use the synthetic varnish buying guide.
Alkyd synthetic varnish, polyurethane and acrylic picture varnish
Traditional “synthetic varnish” in UK decorating language commonly means a solvent-borne alkyd finish. Polyurethane can be used as another varnish resin, sometimes alongside alkyd, when the product is formulated for harder-wearing joinery, furniture or floors. “Polyurethane” alone does not tell you whether cleanup is with water or solvent.
An acrylic picture varnish is a different purchasing category. The eight products in this comparison are described as acrylic or water based; none is a two-pack coating, and none should be promoted into a building varnish merely because it dries clear. Our best synthetic varnish overview ranks bottles within the picture-and-craft set, not tins for architectural timber.
White spirit, water and what you must not mix
The cleanup instructions identify the coating family more reliably than the word “synthetic”. White spirit, also called mineral spirits, is associated with solvent-borne alkyd and oil-based coatings. Water-based varnishes normally specify water for cleaning tools. Wiping bare timber with white spirit during preparation does not turn white spirit into the thinner for the water-based product.
Do not add white spirit to an acrylic or water-based bottle unless its label expressly instructs you to do so. Equally, do not assume that every polyurethane varnish cleans up with solvent: check the exact tin because polyurethane products can be water based or solvent borne.
If you are working with one of the acrylic picture bottles, the application guide covers waits and common film failures; instructions for a joinery or floor tin must come from that product instead.
Doors, floors and the VOC label
For UK building coatings, the legal category matters. Schedule 2 of SI 2012/1715 sets maximum volatile organic compound content for relevant interior and exterior trim varnishes: 130 g/l for water-borne products and 400 g/l for solvent-borne products in subcategory (e). Those figures apply when a product falls within that architectural coating category; they are not a general pass mark for every clear craft liquid.
The acrylic listings do not print a VOC figure, so you should not infer that they meet the trim-varnish limit. For a veneered door, check the door maker’s instructions as well as the varnish label. JELD-WEN, for example, permits polyurethane varnish or stain on relevant veneer edges but advises against oils and waxes on its doors.
Common questions
Is polyurethane a varnish, or a coat you add afterwards?
Polyurethane is a resin used in some varnishes, so polyurethane varnish is already the clear finishing product. You normally choose it instead of another varnish rather than applying it as a universal second layer. If recoating an existing finish, identify that finish and follow the new product’s compatibility and preparation instructions.
Is synthetic varnish the same as polyurethane?
Not necessarily. In decorating, synthetic varnish often refers to a solvent-borne alkyd formulation, while polyurethane identifies a resin that may appear in solvent- or water-based varnish. Labels sometimes describe blends, so the intended substrate, cleanup method and technical sheet matter more than treating the terms as synonyms.
Can I use an acrylic picture-varnish bottle on a door or floor?
You should not assume so. The bottles in this comparison are sold for pictures or crafts, and their listings do not establish suitability for door handling or foot traffic. Choose a joinery varnish for a door and a dedicated floor coating for floors or stairs, following the surface maker’s instructions.
Do I clean a water-based varnish with white spirit?
Usually, tools for a water-based varnish are cleaned with water, but follow the label. A maker may tell you to wipe bare wood with white spirit before applying a water-based film; that is surface preparation, not permission to thin the varnish with solvent. Let the prepared surface dry as directed.
Does the 400 g/l limit apply to the acrylic bottles?
You cannot conclude that from these listings. The 400 g/l figure applies to relevant solvent-borne interior and exterior trim varnishes under SI 2012/1715, while the small acrylic products are presented as picture or craft varnishes and show no VOC figure in the evidence reviewed.
Are two-pack polyurethane coatings included here?
No. None of the retained products in this comparison is described as a two-pack coating. Two-pack systems can have different mixing, pot-life and safety requirements, including potential isocyanate hazards, so read the safety data and obtain competent advice rather than transferring guidance from these one-container acrylic bottles.
Will water-based polyurethane yellow less than solvent alkyd?
A water-based clear finish is often chosen when keeping timber paler is the priority, whereas solvent-borne alkyd can add warmth and amber with age. That is a selection reason, not a lab result or guarantee: timber species, existing finish, film thickness and the exact formulation all affect the final colour.
Related pages
Sources
Public UK sources for the VOC and brushing points on this page. Prices, stars and review counts are from the amazon.co.uk listings extracted on 15 October 2026. Scores use those listings and the review text available on 16 October 2026.
- SI 2012/1715 — VOC in paints and varnishes (retrieved 16 October 2026)
- SI 2012/1715 — Schedule 1, categories (retrieved 16 October 2026)
- SI 2012/1715 — Schedule 2, VOC limits (retrieved 16 October 2026)
- British Coatings Federation — solvent-based paint (retrieved 16 October 2026)
- HSE — paint FAQ (retrieved 16 October 2026)
- Liquitex UK — varnishing acrylics (retrieved 16 October 2026)
- Liquitex — Professional satin varnish (retrieved 16 October 2026)
- amazon.co.uk listings, extracts 15 October 2026 (retrieved 15 October 2026)