Which is best: powder coating or spray paint?

Paint or powder, powder or stove enamel, powder vs spray paint, or powder coat vs air drying? Windridge Coatings is a commercial paint application company. In over 25 years we have applied heavy-duty corrosion protection paints, aesthetic auto paints, powder coatings and stove enamel. We have a fairly good knowledge of all processes and have taken the commercial decision to specialise in powder coating. Powder coating has been the fastest growth area of painting for the last 25 years at the expense of other paint systems.

Powder Coating

Improvements in application techniques have meant small decorative items to heavy and large components are suitable for powder coating. What was once the reserve for architectural and mass production is now available for garden gates and powder coating motorbike frames.

Application equipment for powder coating is more expensive than wet paint systems. The gun alone can cost £4500. The paint is purchased as a powder, hence the name. It is temporarily stuck to the metal with an electrostatic attraction. (In the same way as you rub a balloon on your jumper and watch it stick to a wall, the granules of powder stick to the work piece). The oven is more expensive than stove enamelling because it has to heat the component to a higher temperature, about 200 degrees Celsius.

Why is powder coating better?

Good points:

• Powder coating done properly is tougher than stove enamelling and air drying paints. This means it will take more of punishment before chipping.
• There are no solvents used during the application and so it is environmentally greener.
• Requires factory processing making a better chance of the component being stripped and blasted, for better corrosion resistance and adhesion.
• It produces a more waterproof barrier than liquid paint (for comparable thickness) and therefore offers better protection against corrosion.
• To hide metal imperfections, a Powder coating finish can achieve in two coats, what stove enamelling requires in 15 or more coats.
• Therefore the price is comparable, or even cheaper than stove enamelling.
• Powder coating is more resistant to scratching and marking.
• Good quality powder coatings are available in high gloss and have negligible orange peel.
• Dirt is easily washed off.
• Powder coating can be compounded, polished and waxed like any other paint.

Bad points:

• Cannot be applied on site, therefore not convenient.
• Usually takes 2-3 days to process. (Can be quicker)

This why powder coating has been the fastest growing area of the paint industry for the last 25 years, and why nearly all mass produced items are powder coated.

Stove Enamelling

Stove enamelling is like air-drying paint, but the curing is accelerated by stoving at 120 degrees Celsius. It is sprayed with the sort of spray guns you would expect to see spraying a car in a garage.

Good points:

• Requires factory processing making a better chance of the component being stripped and blasted, for better corrosion resistance and adhesion.
• Excellent finishes can be achieved as each coat can be flattened (rubbed down smooth prior to the next coat, this reduces orange peel).
• It is easier to mask and paint over with a different colour, something very difficult to achieve with powder coating.
• Nearly any colour including metallics can be produced cheaply and in small quantities.
• High gloss and matt finishes are achievable.

Bad points:

• Can be not be applied on site, needs an oven.
• Brittle, will chip if abused.
• Requires many coats to achieve good finish.
• Can suffer from runs if not skilfully applied.
• Does not adhere (stick) strongly to metal, results in chipping.
• Not environmentally friendly due to solvent emissions.

Air drying spray paint

Wet paints can be applied as single pack air-drying or two pack air-drying.

Single pack air drying

Good points:

• Good finish can be achieved.
• Can be applied on site.
• Easy to apply and requires minimal equipment. (Aerosol)

Bad points:

The evaporation of the solvents determines the speed of curing. This can mean the paint remains soft for days and can take weeks for a full cure.

• Generally the most brittle of all three types of painting.
• Does not adhere well to previous powder coating and can peel off.

Two pack paint

Good points:

• Good finish can be achieved.
• Can be applied on site.
• Nearly any colour including metallics can be produced cheaply and in small quantities.
• Adheres better to powder coating than air-drying.

Bad points:

• Not environmentally or user friendly, due to solvent emissions and carcinogens.
• Time consuming, can suffer from contamination whilst wet and sticky.
• Can take days to harden.

If the above reasons where good enough for us to move to powder coating, you may feel the same.

Where can I get a good powder coating job done?

It is another case of you get what you pay for. The powder coating industry suffers from the cowboy element just like any other industry.

• Only go to a company that will ensure the component is grit blasted.
• Ideally the component should be chemically pre-treated to reduce corrosion.
• One coat of powder is not enough it should have a primer.
• Do not allow aluminium components to be stripped of powder coating by blasting alone. It must be chemically stripped first, or it will end up pitted.
• If in doubt ask to see some of their work.