Painting Radiators: The Right Products and How to Avoid Common Mistakes
Which radiator paints actually work — Hammerite Radiator Enamel, Johnstones Radiator Paint — how to prepare the surface correctly, and how to prevent the yellowing that ruins white radiators.
Why radiators need specific products
A radiator operates at surface temperatures between 50°C and 80°C in a typical central heating system. Standard emulsion or satinwood applied to a radiator will soften, yellow, and eventually peel under this heat cycling. Radiator-specific paints are formulated with resins that cure under heat and remain stable across the temperature range of a domestic radiator. Using the wrong product is the single most common reason for a failed radiator finish.
This guide covers the correct products, the essential preparation steps, and the finish options available — including how to keep white radiators white.
Preparation is everything
Like all painting, the quality of a radiator finish is determined mainly by preparation. A poorly prepared radiator will reject even the best radiator enamel within a season.
Start by turning the heating off and allowing the radiator to cool completely to room temperature. Attempting to paint a warm radiator speeds drying time in an uncontrolled way that leads to brush marks setting before they can be worked out, and can cause bubbling in the wet film.
Clean the surface thoroughly with a degreasing solution — sugar soap or a dedicated degreaser such as Zinsser Kleen Strip. Radiators accumulate dust, cooking oils, and finger marks, all of which act as barriers to adhesion. Wipe down, allow to dry, then abrade the surface with 180-grit wet-and-dry paper. You are not trying to remove the existing finish, just to key the surface so the new coating can grip it.
Where the existing finish has chips, rust spots, or areas of peeling paint, use a wire brush or a Dremel with a wire wheel attachment to remove all loose material back to a sound substrate. Spot-prime any bare metal areas with a rust-inhibiting primer before applying the radiator topcoat. For badly degraded cast iron radiators, a full strip back to bare metal followed by a primer and two coats of topcoat gives a much better long-term result than painting over a deteriorated existing finish.
Products that work
Hammerite Radiator Enamel is the most widely available dedicated radiator paint in the UK and is a reliable choice for most applications. It is an alkyd-based coating available in white and a limited range of colours; the white version is formulated to resist the yellowing that affects standard alkyd satinwood when heat-cycled. Apply in two thin coats with a good-quality brush or short-pile foam roller, allowing the first coat to dry hard before applying the second.
Johnstones Radiator Paint is a water-based radiator enamel with a lower VOC than the Hammerite product, making it more suitable for occupied properties or poorly ventilated rooms. The water-based formulation is slightly less durable than solvent-based radiator enamel but performs well on a properly prepared surface and gives good colour retention.
Rust-Oleum Radiator Paint is a newer entrant and offers a wider colour range than either of the above, including deeper colours and metallics. For radiators that are being painted in a feature colour — a dark green, a warm charcoal, or a burgundy — the Rust-Oleum range gives more options.
Zinsser AllCoat Exterior Satin is not marketed as a radiator paint but is widely used by trade decorators for radiators because of its exceptional durability, good colour hold, and broad colour range. It tolerates heat cycling well and is available in any BS or RAL colour. For high-end projects where the radiator paint needs to match a specific wall or woodwork colour exactly, this is the product to specify.
White versus colour radiators
The default in most London interiors is a white or off-white radiator to match the surrounding woodwork. This works well in practice but requires careful product selection to avoid yellowing.
Yellowing in white alkyd-based coatings is caused by the oxidation of the alkyd resin in the absence of light — it occurs on radiators behind furniture, in cupboards, or in rooms with limited daylight. Water-based radiator paints do not suffer from this problem; they do not yellow regardless of light levels. If white radiators in dark positions are a concern, a water-based product like Johnstones Radiator Paint or Dulux Trade Satinwood (water-based) is the better choice.
Coloured radiators have become increasingly popular in London interiors, particularly in period properties where cast iron column radiators are a feature. A deep hunter green, a navy blue, or a warm terracotta on a traditional column radiator reads as deliberate and architectural. When painting in a strong colour, apply the first coat and allow it to fully cure with the heating running gently — this bakes the film and improves adhesion of the second coat.
Brushwork and the detail problem
Radiators are complex three-dimensional objects and painting them cleanly requires patience and the right brushes. A 50mm flat brush for the main panels, a 25mm angled sash brush for fin sections, and a 12mm or 19mm pencil brush for the deepest recesses of column radiators.
Work from top to bottom and from the back of the radiator to the front. This minimises the chance of brush marks on visible surfaces being caused by working over already-painted areas. Lay off the final strokes in a consistent direction — typically vertical on column radiators — to give a uniform appearance when the paint dries.
For advice on radiator painting as part of a wider interior decoration project, contact our team or request a free quote. We work across Belgravia, Chelsea, Kensington, and throughout central London.