How to Paint Carbon Fibre Step by Step

Carbon fibre can be painted in a similar way to other automotive parts, but the key is to avoid damaging the carbon fibres during sanding. If the original clear coat is sound and firmly bonded, it only needs to be properly degreased and sanded. If sanding exposes cured resin and the carbon will subsequently be completely covered with colour, we recommend a 2K epoxy primer.

Carbon fibre parts are now widely used on cars, motorcycles, bicycles and interior components. Over time, the original clear coat may lose its gloss, crack or begin to peel. Carbon can also be fully refinished in a different colour or with a special effect paint.

Painting carbon fibre is not particularly difficult. The most important part is correctly assessing the condition of the surface and avoiding damage to the carbon fibres during preparation. In most cases, you are not actually painting directly onto carbon fibre, but onto the original clear coat or the cured resin in which the fibres are embedded.

First check the condition of the carbon fibre part

Inspect the part carefully before starting. There are three common situations:

1. The original clear coat is sound and firmly bonded.
   The surface is not cracked or peeling. In this case, there is no need to remove the original clear coat down to the carbon. Proper cleaning, degreasing and sanding are sufficient.
2. The clear coat is weathered, cracked or peeling.
   The damaged coating needs to be removed until you reach a sound, firmly bonded layer. The transition into the remaining coating should be smooth.
3. Cured resin or the carbon fibres themselves are exposed.
   If only solid, undamaged cured resin is exposed, the surface can continue to be prepared for painting. If the carbon fibres are frayed, sanded through or mechanically damaged, the composite itself must be repaired first.

Important: a carbon fibre composite is not the same as an ordinary plastic part. A plastic adhesion primer is therefore not automatically required on genuine carbon fibre.

What you will need

• cleaning products and clean cloths,
• HB BODY 770 Antisil Silicone Remover / Degreaser or HB BODY 770 Antisil Spray,
• suitable abrasives,
• masking materials,
• a 2K epoxy primer or filler where required,
• basecoat or effect paint if the carbon will be completely refinished,
• a high-quality 2K clear coat,
• a respirator, protective gloves and safety glasses.

When sanding carbon composites, always use suitable respiratory protection and, where possible, dust extraction. Do not inhale fine sanding dust.

How to paint carbon fibre step by step

1. Clean the part thoroughly

First remove ordinary dirt, dust and residues of wax, polish and other surface treatments.

Carbon parts are often protected with wax, sealants or ceramic coatings. These products can significantly reduce the adhesion of a new paint system. Remove them thoroughly before sanding so that contamination is not worked into the surface.

2. Degrease the surface

After cleaning, use a degreaser designed specifically for paint preparation. A suitable option is HB BODY 770 Antisil.

The two-cloth method works well: use one clean cloth to apply the degreaser and dissolve contamination, then immediately remove it with a second clean, dry cloth.

Do not use cellulose thinner or aggressive solvents simply to achieve stronger degreasing. Some resins and older coating systems may be sensitive to strong solvents.

3. Sand a sound original clear coat

If the original clear coat is firmly bonded, there is no need to remove it. The aim is simply to remove all gloss and create an evenly matt surface for the next coating.

Depending on the coating system that will follow, suitable grits may include:

• P600–P800 before applying a coloured basecoat,
• P800–P1000 for fine preparation before applying a new clear coat.

Suitable products include SIA P800 Wet Sanding Paper and SIA P1000.

After sanding, the complete surface should have an even matt appearance. Any remaining glossy areas indicate that the surface has not been prepared sufficiently.

Take particular care around edges. The coating is usually thinnest in these areas and can easily be sanded through. Sand edges and complex shapes by hand using minimal pressure.

4. Remove damaged or peeling clear coat

If the original clear coat is peeling, cracking or separating from the substrate, simply matting the surface is not sufficient.

Sand away the damaged coating until you reach a sound, firmly bonded surface. Feather the transition between the repaired area and the remaining original coating so that no hard edge is visible after refinishing.

For more pronounced defects or feather-edging, you can carefully start with SIA P400 Wet Sanding Paper and then refine the surface with finer grits.

With carbon fibre, the objective is not to reach bare material as quickly as possible. If an existing coating is sound and firmly bonded, there is no reason to remove it unnecessarily.

5. Do not sand into the carbon fibres

Sanding through the clear coat and exposing cured resin is not necessarily a problem.

However, stop sanding as soon as the carbon fibres themselves begin to be affected.

Warning signs include:

• individual fibres becoming visible,
• a frayed surface,
• damage to the carbon weave,
• cracks or depressions in the laminate,
• other mechanical damage to the composite.

At this point, the issue is no longer simply a paint defect. The carbon composite itself needs to be repaired before refinishing.

6. Does carbon fibre need a primer?

A sound, firmly bonded original coating normally does not need an additional primer. If cured resin is exposed and the carbon will subsequently be covered with colour, we recommend a 2K epoxy primer.

If the existing clear coat is sound and has been prepared correctly, there is normally no reason to add a primer simply because the part is made from carbon fibre.

A primer becomes useful when sanding has exposed cured resin, when repairs have been carried out or when different substrates need to be isolated and unified before a full colour refinish.

2K epoxy primer – our preferred option

If the carbon will be completely covered with colour and cured resin has been exposed during preparation, we recommend 2K PRO 2K Epoxy Primer 400 ml as a stable intermediate layer.

An epoxy primer provides good isolation, strong adhesion and a stable surface for the subsequent coating layers.

Apply it only to a clean, dry, degreased and correctly sanded surface, and always follow the application instructions in the product's technical data sheet.

HB BODY P360 – an alternative with filling properties

If you also need to level minor surface imperfections, HB BODY P360 2K HS Primer / Filler can be used as an alternative.

This 2K high-build primer is suitable for substrates including old paintwork, fibreglass, polyester fillers, bare steel and other automotive surfaces. Its suitability for correctly prepared carbon composites has also been confirmed to us by an HB BODY representative.

P360 is particularly useful when minor surface irregularities also need to be levelled. The manufacturer recommends two thin coats with a total film thickness of approximately 50–60 µm. Once dry, it can be prepared for further painting with P400–P600, or P800–P1000 when wet sanding by hand.

If you are unsure about the exact type or condition of the carbon composite, we prefer a 2K epoxy primer.

7. Prepare the primer for the next coating

Allow the primer or filler to dry fully and sand it according to the technical data sheet of the product used.

The surface should be smooth, evenly matt and free from sharp transitions, pores or visible sanding scratches.

Remove all sanding dust and degrease the surface again. From this point onwards, avoid touching the prepared surface with bare hands.

Option A: I want the carbon weave to remain visible

If you want to retain the visible carbon weave, do not use an opaque primer or filler on the visible surface.

If the original clear coat is sound and firmly bonded, a typical system is:

carbon composite → sound original clear coat → sanding → new 2K clear coat

For final protection, you can use 2K PRO Gloss 2K Clear Coat. If you prefer a matte carbon finish, 2K PRO Matte 2K Clear Coat is also available.

For exterior carbon parts, a high-quality clear coat is also important for long-term protection against UV radiation and weathering.

If the original clear coat has been removed down to the resin and the carbon is to remain visible, first carry out a test application with the intended transparent coating system. Damaged or porous laminates may require resin repair before the final clear coat is applied.

Option B: I want to completely repaint the carbon

If the carbon weave is to disappear completely and the part will be refinished with a solid or effect paint, the coating system is more straightforward.

On a sound original coating, the system may be:

carbon → sound original coating → sanding → basecoat → 2K clear coat

If the repaired surface contains different substrates or cured resin is exposed in places:

carbon composite → 2K epoxy primer / suitable 2K filler → sanding → basecoat → 2K clear coat

8. Apply the basecoat or effect paint

Apply the colour in several even coats. Do not try to achieve full coverage with one excessively heavy coat.

Allow the correct flash-off time between coats according to the paint system being used.

Even application is particularly important with Pearl, Candy, Chameleon and other effect paints. Variations in the amount of material applied can affect both the final colour and the effect.

9. Apply a 2K clear coat

Once the basecoat or effect paint has flashed off correctly, apply the protective clear coat.

For automotive, motorcycle and other demanding applications, we recommend a high-quality 2K clear coat, such as 2K PRO Gloss 2K Clear Coat 400 ml.

The clear coat provides the final appearance and protects the coloured coating from mechanical wear, chemicals, UV radiation and weathering.

Always observe the recoating window of the basecoat or effect paint and follow the clear coat manufacturer's application instructions.

10. Allow the coating system to cure properly

A freshly painted part may become touch-dry relatively quickly, but that does not mean the coating system has fully cured.

Do not rush installation, tightening bolts, applying adhesive tapes or intensive polishing. Full curing time depends on the coating system, film thickness and temperature.

Can faded carbon fibre simply be polished?

Yes, if the damage is only superficial.

If there is still sufficient clear coat and it has only lost gloss or developed fine scratches, fine sanding followed by polishing may be enough.

If the clear coat is cracked, peeling, heavily yellowed or missing in places, polishing alone will not solve the problem. The surface needs to be refinished and clear coated again.

Common mistakes when painting carbon fibre

Unnecessarily sanding down to the carbon

If the original coating is firmly bonded, there is no reason to remove it completely. Doing so only increases the risk of damaging the carbon fibres.

Using excessively coarse abrasives

Use coarse abrasives only where damaged material actually needs to be removed. Take particular care on edges and areas where the coating is thin.

Poor degreasing

Wax, silicone, polish and ceramic coatings can cause poor adhesion, cratering, fisheyes and other paint defects.

Painting over peeling original coating

A new coating can only adhere as well as the layer beneath it. All loose or poorly bonded original coating must be removed.

Automatically using a plastic primer

A carbon composite is not the same as an uncoated PP or PE plastic part. A plastic adhesion primer is therefore not a universal solution for carbon fibre.

Using an opaque primer when the carbon needs to remain visible

Both 2K epoxy primer and P360 are opaque. They should therefore only be used where the carbon will subsequently be completely covered with colour.

Carbon fibre painting – quick step-by-step summary

1. Clean the part thoroughly.
2. Remove wax, silicone and grease.
3. Check the condition of the original clear coat.
4. If the coating is sound, simply sand it evenly.
5. Remove damaged or peeling coating until you reach a sound substrate.
6. Do not sand into or damage the carbon fibres.
7. If cured resin is exposed and the carbon will be covered with colour, apply a suitable 2K primer – preferably epoxy.
8. HB BODY P360 can be used where additional filling properties are useful.
9. Once cured, sand the primer and degrease the complete surface again.
10. Apply the basecoat or effect paint if the appearance is being changed.
11. Finish with a high-quality 2K clear coat.
12. Allow the complete coating system to cure sufficiently.

The most important rule: if the existing surface is sound and firmly bonded, there is no need to sand all the way down to the carbon. The objective is to create a clean, stable and evenly prepared substrate – not to remove as much of the original material as possible.