How the two finishes work

Powder coating is a dry finishing process. A spray gun applies an electrostatically charged powder to an earthed metal part, and the powder clings until the part goes into an oven. There, typically between 180°C and 200°C, the powder melts, flows and chemically cross-links into a hard, continuous film. The result is a tough coating with no solvent to evaporate, ideal for fabricated steel and aluminium.

Wet painting, by contrast, uses a liquid paint — solvent-based, water-based or two-pack — applied by spray gun, aerosol, brush or roller. The coating dries or cures as solvents flash off and, in the case of two-pack products, a chemical reaction hardens the film. It is the traditional route for complex shapes, small batches and any job where colour matching or a very specific finish matters.

Durability and protection

For sheer toughness, powder coating usually has the edge. A typical powder film is 60–120 microns thick, compared with 25–50 microns for many wet paint systems. That extra build gives excellent resistance to chipping, abrasion and many chemicals. Polyester powders hold colour well outdoors, suiting gates and garden furniture. Epoxy powders are harder and more chemical-resistant but tend to chalk in sunlight, so they suit interior brackets, machine guards and under-bonnet components.

Wet paint is no weakling, though. A well-applied two-pack epoxy primer followed by a polyurethane topcoat can be remarkably durable, with better flexibility than powder on parts that flex or expand. It also reaches into recesses, box sections and tubular joints where powder struggles. In coastal or heavily salted environments, a zinc-rich primer plus a quality topcoat often outperforms powder on complex fabrications. The weak point for both is preparation: a perfect coating over mill scale, rust or oil will fail quickly.

Colour range and finish options

Here wet paint wins comfortably. You can mix almost any colour, match a classic car shade, add metallic, pearl, candy or flake effects, and order a single litre for a small job. Powder is stocked in a wide range of RAL and BS colours, plus textures, matt, satin and gloss, but custom colours often mean a minimum order quantity and a longer lead time.

Powder also gives a very consistent, factory-like finish across a batch, with no brush marks, runs or sags. Wet paint, especially from an aerosol or brush, shows the human hand more readily. If you need a flawless show finish in a bespoke colour, painting is usually the practical answer. If you need 50 identical brackets in RAL 7016, powder is hard to beat.

Application methods and equipment

Powder coating needs a dedicated setup: a powder gun and control unit, an earthing point, a spray booth or at least a clean, ventilated area, and an oven large enough for the whole part. That oven size is the big DIY limitation. You cannot powder coat a 3-metre gate in a domestic oven, and most powder formulations need a full cure at temperature rather than a low bake. Small parts are feasible with a second-hand gun and modified oven, but larger work goes to a specialist coater.

Wet painting is far more accessible. An HVLP spray gun and a compressor will handle most workshop jobs, while aerosols and brushes cover touch-ups and small areas. You can paint a large fabrication in sections, and low-bake or air-dry products suit parts that cannot take high heat. The trade-off is more skill in technique: gun distance, overlap, flash-off times and recoat windows all affect the result. Two-pack paints also demand proper respiratory protection because of isocyanates.

Surface preparation and practical workshop tips

Both finishes live or die by preparation. Degrease first, then remove rust and mill scale by abrasive blasting, grinding or a chemical prep. A phosphate pre-treatment improves adhesion and corrosion resistance. Aluminium benefits from an etch primer or a specific pre-treatment. For powder, make sure the part is fully earthed and free from blind holes that trap air; preheat thick sections to avoid outgassing bubbles. Be aware of the Faraday cage effect, where powder struggles to reach deep recesses — a gentle reflow or a touch-up with wet paint can solve this.

• Powder: excellent edge coverage, but difficult to touch up invisibly; a repair often means stripping and recoating.
• Wet paint: easy to touch up, blend and repair, but more prone to runs, sags and solvent popping if applied too heavily.
• Thin sheet: powder curing can distort lightweight panels; wet paint is gentler on thin or heat-sensitive parts.
• Welds: clean weld spatter and grind smooth before either finish; powder will highlight poor welds, paint can hide minor imperfections.

Which finish suits your project?

Choose powder coating for high-volume production, simple shapes, outdoor durability and a uniform factory finish. It is ideal for gates, frames, shelving, chassis components, machine covers and anything likely to be knocked about. Choose wet paint for complex geometry, bespoke colours, classic restoration, small one-off jobs and parts that need touching up later. Many UK workshops use both.

If you are weighing up a home setup, start with wet paint. It is cheaper to enter, more forgiving of part size and easier to repair. If you repeat the same parts in a stock colour, consider powder or a local coater. Either way, spend your time on preparation. A mediocre coating on perfectly prepared metal will outlast a premium coating on a rusty, oily surface every time.