Car and bodywork filler 

Fillers are products belonging to the family of primers and adhesion primers, used not only in automotive bodywork painting but also in industrial painting. They play a key role in the various stages of painting systems. They are applied as levelling and filling layers directly onto bare metal surfaces, prior to the application of primers, paints, and Topcoats.

Fillers are resin-based products, either epoxy or polyester, infused with fine powders that provide them with their filling properties, high resistance, and ease of sanding.

Fillers come in the form of thick pastes, accompanied by a hardener. They are used to fill and level surfaces that must be corrected by the painter following impacts or significant scratches.

The application of filler on a vehicle comes directly after dent removal. The filler can be applied in thicknesses ranging from 1 mm to 2 cm, without risk of shrinkage during curing and drying.

These resins cure with the aid of a coloured catalyst. The colouring of the catalyst ensures uniform mixing. Once the catalyst is added and blended into the filler, the curing process is extremely rapid. The filler sets in just a few minutes and can be sanded immediately.

Different types of fillers

Among the fillers used in professional painting applications, there are the traditional fillers (a thick pink paste) suitable for general use.

There are also special fillers, such as aluminium filler — an epoxy-based paste loaded with aluminium powder. This provides both a metallic appearance and enhanced resistance and hardness once cured.

For repair work on carbon fibre panels and frames, there is a new filler loaded with carbon filaments, offering exceptional hardness and lightness compared to other types of filler.

Lastly, Stardust offers a special low-viscosity filler, which can be sprayed using a conventional spray gun. Significantly thicker than a standard primer, this liquid filler enables filling and levelling of even the most irregular surfaces.

Sanding fillers

Before applying filler, it is recommended to prepare the surface with aggressive sanding (using P120 grit) to optimise adhesion. The sanded area should extend well beyond the immediate impact area, as the filler should be applied across the surrounding zone.

Once cured, fillers must be sanded before being primed. Sanding is typically done with grit ranging from 180 to 320, throughout the sanding process.

It is absolutely essential to prime the filler before applying the paint. Only a primer can create the perfect surface condition required for the paint.

On which substrates can fillers be applied?

All substrates can receive filler, provided they are properly sanded. Most metals can be coated directly with filler. In fact, fillers provide excellent adhesion without an adhesion primer on most ferrous and many non-ferrous metals. However, it is vital to sand the metal thoroughly and degrease it prior to filler application.

Tips for applying filler properly.

► Please refer to our tutorial on filler application.

Dispense an approximate dose of about 2% catalyst onto the filler. Mix thoroughly using a criss-cross motion with metal spatulas until a uniform colour is achieved, indicating complete blending of the filler with the coloured hardener.

Caution: once the catalyst is mixed in, the filler must be applied to the surface immediately.

Apply the filler in decisive and smooth movements, spreading it generously, and importantly, avoid working repeatedly over the same area.

Anticipate applying a slightly thicker layer, so that you can sand it back without needing to reapply multiple coats.

Where possible, aim to apply the correct amount of filler: applying too much will result in unnecessary sanding work; applying too little will require further filler application.

After full curing (around 5 to 10 minutes), you can proceed to sanding, using either a power sander or a sanding block.

Primers in Cans

Colouring Chrome