Conventional Paint System

A conventional system is where a solid colour of hard paint or enamel is painted over a primer, and no clear coat or lacquer is used. At one time, most cars were painted this way, with the exception of metallic colours, but now most vehicles are painted with clear-over-base.

Commercial vehicles may still be painted with a conventional paint system.

What it means

A conventional paint system is the familiar bodyshop process for refinishing a car. The technician repairs and prepares the panel, applies primer, then sprays a solvent-based basecoat to give the colour, followed by a clear lacquer (clearcoat) to provide gloss and protection. This multi-layer approach has been the standard in vehicle refinishing for many years, especially with 2K (two-pack) solvent systems.

Why it matters

Knowing which system you are looking at decides how the repair proceeds. Conventional means working through primer, colour and clearcoat in a familiar order, rather than dealing with specialist or unusual coatings, and that shapes everything from materials to sequence.

Correction follows the same logic. On a conventional system polishing and sanding work almost entirely in the clearcoat, and once damage reaches through to colour or primer the job moves into repair and repaint territory rather than machine work. Colour matching depends on it too, since many cars, particularly older ones and previously refinished panels, were done with conventional solvent-based systems, and the paint manufacturer will specify conventional formulas to get a match.

It is worth knowing this is not the same as factory paint. Modern OEM plants use waterborne basecoats in tightly controlled low-VOC systems, and a conventional refinishing system is built to work alongside those without being identical to them.

Which cars carry one

You will see the phrase conventional paint system in paint manufacturer datasheets, technical bulletins and bodyshop estimates. It is often used to distinguish standard solvent-based refinishing products and methods from newer water-based, ultra high-solids, special effect or OEM-only systems. Inspectors and detailers may also refer to conventional refinished panels when discussing how a car has been repaired in the past.

Context

Conventional paint systems sit alongside clear over base as the everyday language of bodyshops. In practice, a conventional system usually means a familiar sequence of primer, solvent-based basecoat and 2K clearcoat that can be sanded, polished and blended in predictable ways. As regulations and OEM processes have evolved, more water-based and low-VOC products have entered the market, but many repairers still refer to their main refinishing line as a conventional system to distinguish it from specialist or OEM-only technologies.

Common mistakes

• Assuming that all factory paint is the same as a conventional refinishing system, when OEM production lines may use different chemistry and curing methods.
• Expecting every defect in a conventional system to be correctable by polishing, even when damage has gone through the clearcoat into the colour or primer.
• Mixing products from different paint systems - primers, basecoats and clearcoats - without checking compatibility, which can lead to issues such as die back, solvent migration or poor adhesion.
• Judging a conventional repaint solely on gloss, without checking colour match, texture and blend into adjacent factory panels, which are just as important to the overall result.

Authored by Danny Argent. Reviewed by Gary Wray. Last updated 16 May 2026.