What Should I Use to Degrease the Surface Before Painting?

Short answer

Before painting, use products designed specifically for degreasing surfaces before coating, such as silicone remover or a professional paint degreaser. The surface must be clean, dry, sanded and free from grease, silicone, wax, dust and residues of old cleaning products.

Petrol, technical petrol, standard thinners, household cleaners and universal degreasers are not suitable. They may leave a greasy film, attack the substrate, evaporate too quickly or simply spread contamination across the surface.

Degreaser is available in a can or container for application with a clean cloth, or as a spray for easier application. In both cases, the contamination must be wiped away from the surface, not just spread around or left to dry.

Why is degreasing so important?

Degreasing is one of the most important steps before painting. Even a very thin layer of grease, silicone, wax or cleaning product residue can cause poor adhesion, craters, fish eyes, stains, patches or peeling later.

The surface may look clean at first glance, but it can still contain contamination that only becomes visible after applying paint or clear coat. With effect paints, surface cleanliness is especially important because defects in the base can be very visible in the final result.

What should be used to degrease the surface?

For painting, it is best to use a degreaser designed specifically for automotive paint preparation. This is usually a silicone remover or a professional paint degreaser.

• Silicone remover: suitable for removing grease, silicone, wax and polish residues.
• Paint degreaser: designed for surface preparation before painting.
• Spray degreaser: practical for smaller areas, edges, recesses and hard-to-reach places.
• Degreaser in a can or container: suitable mainly for larger surfaces and use with a clean lint-free cloth.

Degreaser in a can or as a spray

Degreasers intended for paint preparation are available in different forms. They are most commonly supplied either in a can or container for application with a clean cloth, or as a spray for easier application on smaller areas, edges, recesses and hard-to-reach places.

Degreaser in a can or container is especially suitable for larger areas. It is applied with a clean lint-free cloth and the contamination is wiped away with a second clean cloth. It is important not to let dirty degreaser dry on the part.

Spray degreaser is practical for quick and easy application, but the released contamination still needs to be wiped off with a clean cloth. Simply spraying degreaser onto the part does not replace proper wiping of the surface.

How to degrease the surface correctly

Correct degreasing does not mean just wiping the surface with something. The goal is to actually remove contamination from the surface. If dirty degreaser is allowed to dry on the part, the contamination can remain on the surface.

• use a clean lint-free cloth,
• apply degreaser to the surface or to the cloth,
• wipe the surface evenly,
• use a second clean cloth to wipe off the released contamination while the surface is still wet,
• do not let dirty degreaser dry on the part,
• do not touch the surface with bare hands after degreasing,
• allow the surface to flash off completely before painting.

What should be avoided when degreasing?

Not every product that removes grease is suitable for paint preparation. Some products can leave residues, leave a film or attack the substrate.

• Petrol and technical petrol: can leave a greasy film and are not a reliable choice before painting.
• Standard thinner: is not a proper degreaser. It can spread contamination, attack old coatings or react unnecessarily with the surface.
• Brake cleaner: is not a safe choice for paint preparation. Depending on the type, it can be too aggressive, evaporate too quickly or leave unwanted residues.
• Household cleaners: may contain fragrance, polishing agents, waxes or other additives unsuitable under paint.
• Dirty cloths: can bring grease, dust or fibres back onto the surface.

When should the surface be degreased?

It is useful to degrease the surface before sanding and again after sanding. Degreasing before sanding helps prevent grease and silicone from being pushed into the surface during sanding. After sanding, dust, residues and contamination must be removed before applying further layers.

Before painting, the surface must be dry, clean and fully flashed off. Degreaser must not be trapped under paint or clear coat.

Does an anti-static tack cloth replace degreasing?

No, an anti-static tack cloth does not replace degreasing. It is mainly used to remove fine dust shortly before painting. It should only be used on a prepared, dry and degreased surface.

An anti-static tack cloth can be very useful as the final step before applying paint or clear coat, but it does not remove grease, silicone or wax residues in the same way as a proper degreaser.

What can happen if the surface is not degreased properly?

A poorly degreased surface can cause problems immediately during painting or later after curing. Typical defects include craters, fish eyes, bubbles, greasy patches, poor adhesion or peeling.

In clear coat, contamination often appears as areas where the coating refuses to flow or pulls away from the surface. With effect paints, poor degreasing can cause patches, uneven appearance or visible defects under the final clear coat.

How to prevent the problem

• use only degreaser intended for paint preparation,
• do not use petrol, technical petrol or standard thinner,
• work with clean lint-free cloths,
• always wipe off contamination with a second clean cloth,
• do not let dirty degreaser dry on the surface,
• do not touch the surface with bare hands after degreasing,
• allow the surface to flash off completely before painting,
• shortly before painting, use an anti-static tack cloth to remove fine dust.

Summary

• Before painting, use silicone remover or a professional paint degreaser.
• Degreaser can be supplied in a can for cloth application or as a spray for easy use.
• Simply spraying degreaser is not enough, released contamination must be wiped off with a clean cloth.
• Petrol, technical petrol, standard thinners, household cleaners and dirty cloths are not suitable.
• An anti-static tack cloth helps with fine dust, but does not replace degreasing.
• Poor degreasing can cause craters, fish eyes, patches, poor adhesion or peeling.