Paint Priming

"Paint Priming" is a term which has recently entered the lexicon of the detailing industry, and it seems to mean different things to different people.

We have heard it used in terms of priming the paint ready for polishing -- which means doing all the usual prep of using a TFR, detailing clay, panel wipe etc.

But we have also heard it used in terms of priming the paint ready to accept a wax or coating. There are even primer polishes now.

This is not a term we like because it sounds too much like paint primer, which is something completely different. Also, because there is no real agreement on what it means. I suspect that this term has come about that this term has come about as a result of some marketing gimmickry, to make 'cleaning paint' sound more technical.  

What it means

Paint priming is the stage in a repair or respray where primer is applied to prepared panels. After any metalwork, plastic repair or filler work has been finished and sanded, the technician degreases the area and applies suitable primer products. These may include etch or epoxy primers on bare metal, adhesion promoters on plastics and high-build primers over repair areas that need levelling. Once cured and sanded smooth, the primed surface is ready for base coat and clearcoat.

Why it matters

• Provides a sound base for paint: Correct priming helps colour and clearcoat stick properly, reducing the risk of peeling, flaking or mapping around repair edges.
• Adds protection: On steel and other metals, priming is a key part of corrosion protection, sealing repaired areas that no longer have factory E-coat or original paint.
• Levels repairs: High-build priming and careful flatting help hide sanding marks and minor lows so the final topcoat looks smooth and even.
• Affects final finish quality: Poor priming can telegraph through as sinkage, edge-mapping, texture differences or early die-back in the topcoat.

Where you’ll see it

You will see paint priming mentioned on bodyshop estimates, repair methods and technical data sheets. Typical phrases include prime repaired area, epoxy prime bare metal, high-build prime and flat before base coat or panel prepared and primed ready for paint. Inspectors and detailers may also refer to poorly primed repairs where edges, rub-throughs or corrosion are starting to show.

Context

Paint priming sits between bare substrate and visible paintwork in the overall paint stack. A typical sequence is E-coat on the shell from the factory, then repair work as needed, followed by suitable primers, then base coat and clearcoat. Different primer types are chosen depending on whether the substrate is steel, aluminium, plastic or filler, and on the paint system being used. When polishing and correcting paint, you should never be cutting as far as the priming layer. If primer is visible, the clearcoat and often the base coat above it have already been compromised, and repair and repaint is normally the correct next step.

Common mistakes

• Skipping proper priming and applying base coat straight over bare metal, plastic or filler, which can lead to poor adhesion and early failure.
• Using the wrong primer type for the substrate, such as standard surfacer on plastics that really need an adhesion promoter or epoxy.
• Leaving heavy sanding marks, pinholes or filler edges in the primed surface and expecting the topcoat alone to hide them.
• Building primer too thick or rushing flash-off and curing times, trapping solvents that later cause sinkage, die-back or solvent mapping in the finished paint.

Written by Danny Argent. Last updated 21/11/2025 16:56