Which paint should I use on radiators?
Which paint should I use on radiators?
A radiator enamel — water-based acrylic ones no longer yellow, which ordinary gloss on a hot surface always will.
The rule that matters is that the radiator must be cold, off and preferably fully cooled overnight before painting, and left to cure before the heating goes back on. Painting a warm radiator makes the solvent flash off before the paint has levelled, giving a ridged finish, and heating a fresh film traps solvent and produces the smell that lingers for weeks. Ordinary oil-based gloss yellows in the dark and yellows faster when hot, which is why radiators behind curtains and furniture discolour first. A coat of paint reduces heat output very slightly — a few per cent at most — and that is dominated by colour and surface texture rather than by the paint being present.
The options, ranked
| Option | Good at | Bad at |
|---|---|---|
| Water-based radiator enamel | Formulated to stay white at radiator temperatures, low odour, and quick to recoat. | Slightly less hard than solvent-based enamel until it has fully cured over a few weeks. |
| Solvent-based radiator enamel | Very hard, flows out beautifully to a smooth film. | Strong smell in a room you have to live in, and it can still yellow slightly out of daylight. |
| Ordinary emulsion | Matches the wall colour exactly if the radiator is meant to disappear. | Not designed for heat, so it discolours and can soften; use only with a heat-tolerant clear coat if at all. |
| Radiator spray | Even coverage over the fins and columns of a shaped radiator that a brush cannot reach. | Requires masking a whole room, and the radiator ideally comes off the wall. |
Technique that changes the outcome
- Turn the heating off and let the radiator cool completely
- Wash off dust and grease, then key the existing finish with a fine abrasive pad
- Prime bare or rusted patches with a metal primer first
- Two thin coats, and leave the heating off until the recoat and cure times have passed
What goes wrong
- Painting a warm radiator
- Painting the valves or a thermostatic valve head, which stops it sensing the room correctly
- Ordinary oil-based gloss if you want it to stay white
Compiled practical guidance rather than a published standard. Product formulations vary by brand and market, so read the label — and where the work is structural, electrical or gas, the regulations that apply where you are govern rather than anything here.
Other paint questions
| For | Use |
|---|---|
| Previously painted wood | Clean it, key it and spot-prime bare areas — and find out first whether the existing paint is oil or water based. |
| Bare wood | Knotting solution on the knots, a wood primer, then your topcoat — and prime end grain twice. |
| Plastic | Any paint, provided an adhesion promoter goes on first — and on polypropylene or polyethylene, the promoter is not optional. |
| Kitchens | A scrubbable acrylic eggshell or satin on the walls — and for cabinets, degrease, prime and use a proper cabinet enamel. |
| Bathrooms | A moisture-resistant acrylic in a satin or eggshell sheen with a mould inhibitor — but ventilation, not paint, is the actual fix. |
| Metal | Remove the rust, apply a rust-inhibiting primer the same day, then an alkyd or a direct-to-metal acrylic. |
| Ceilings | A flat matt emulsion — and if there is a water stain or nicotine, seal it with a shellac-based stain block first. |
| Tiles | Tile paint over an epoxy or adhesion primer on a thoroughly degreased and abraded glaze — and expect a limited life in a shower. |
| Fences | A penetrating stain or fence treatment rather than a film-forming paint — and let new pressure-treated timber weather first. |
| Floors | Two-pack epoxy on concrete after a moisture test and a proper grind; floor-grade varnish or floor paint on timber. |
| Exterior masonry | A breathable mineral or masonry paint — and on an old solid wall, breathability matters more than any durability claim. |
| Galvanised metal | A mordant wash, a self-etch primer or a purpose-made acrylic primer for galvanising — ordinary oil-based primer peels off in sheets. |
| UPVC | A uPVC-specific paint or an adhesion promoter with an acrylic topcoat — and avoid dark colours, which can distort the frame. |
Common questions
- Which paint should I use on radiators?
- A radiator enamel — water-based acrylic ones no longer yellow, which ordinary gloss on a hot surface always will.
- What should I avoid?
- Painting a warm radiator Painting the valves or a thermostatic valve head, which stops it sensing the room correctly Ordinary oil-based gloss if you want it to stay white
Related pages
- Which paint goes over previously painted wood? Clean it, key it and spot-prime bare areas — and find out first whether the existing paint is oil or water based.
- Which paint should I use on bare wood? Knotting solution on the knots, a wood primer, then your topcoat — and prime end grain twice.
- Which paint sticks to plastic? Any paint, provided an adhesion promoter goes on first — and on polypropylene or polyethylene, the promoter is not optional.
- Which paint should I use in a kitchen? A scrubbable acrylic eggshell or satin on the walls — and for cabinets, degrease, prime and use a proper cabinet enamel.
- Which paint should I use in a bathroom? A moisture-resistant acrylic in a satin or eggshell sheen with a mould inhibitor — but ventilation, not paint, is the actual fix.
- Which paint should I use on metal? Remove the rust, apply a rust-inhibiting primer the same day, then an alkyd or a direct-to-metal acrylic.
- Which paint should I use on a ceiling? A flat matt emulsion — and if there is a water stain or nicotine, seal it with a shellac-based stain block first.
- Which paint can I use on tiles? Tile paint over an epoxy or adhesion primer on a thoroughly degreased and abraded glaze — and expect a limited life in a shower.
- Which paint should I use on a fence? A penetrating stain or fence treatment rather than a film-forming paint — and let new pressure-treated timber weather first.
- Which paint should I use on a floor? Two-pack epoxy on concrete after a moisture test and a proper grind; floor-grade varnish or floor paint on timber.
Sources
- Typical range compiled from manufacturer specifications — At One Place