Automotive Primers: Which Should I Use?

16 February 2023 Automotive

We all know that primers are used to prevent corrosion, improve adhesion and create a smooth, stable surface for topcoats. But with such an array of primers available it can be confusing to know which primer is best, especially as some primers are known by more than one name. One thing we can be sure about is there’s no such thing as a ‘one size fits all’ primer.

To simplify this, let’s take a look at the types of primer in the ProXL range.

Etch Primers

Etch primers contain an acid that etches into the surface of the metal to increase adhesion between it and the primer. This replicates the cataphoretic dip priming process used in car manufacturing.


ProEtch is a fast-drying acid etch primer that improves adhesion with many difficult substrates including alloy, stainless steel, Zintec and galvanised steel. It produces a super smooth non-porous finish that is suitable for any topcoat.

It is sold as a 500ml aerosol with two nozzles, one being the unique Vari-nozzle that gives a choice of spray pattern at a turn.


UltraEtch is an outstanding all-purpose epoxy etch primer that provides excellent adhesion and corrosion prevention on sheet steel, zinc-coated steel, aluminium and anodised aluminium.

It is very fast drying with excellent flow out and can be used wet-on-wet with a super smooth finish.

UltraEtch is sold as a 1-litre tin or 500ml aerosol.

Adhesion Promoter Primer

Adhesion promoter primers aren’t the same as basecoat primers for topcoats but are used to improve the adhesion of vehicle trims etc.


UltraGrip is a technically-advanced adhesion promoter that offers excellent adhesion to virtually any substrate. It is fast drying, with very low film build-up.

It has been tested on most types of plastic, and non-ferrous metals including aluminium and stainless steel, glass, porcelain and electro-coated substrates.

It is sold as a 1-litre tin or 500ml aerosol.

1k High-Build Primers

High-build primers combine the features of a basecoat primer and a fine surface filler to simultaneously protect against corrosion, improve adhesion and smooth out minor surface imperfections. This combination reduces the number of processes required to prepare a surface for the topcoat.


This is a unique high-build spray filler-primer that provides excellent adhesion to many difficult substrates including plastics and aluminium.  It dries fast, sands easily and is compatible with water and solvent-based topcoats.

UltraBuild is available in grey, black and white, and is sold as a 500ml aerosol.


This is an ultra-high performance primer that combines excellent film build and hold-up with an exceptionally quick dry-to-sand time.

It can be used directly on many substrates including bare metal and most plastics and is suitable for water or solvent-based topcoats.

XpressBuild is available in grey, black, white, red and blue, and is sold as a 500ml aerosol.


SpectroPrime is a coloured primer-surfacer for fast spot-priming under topcoats that present difficult coverage, delivering an exceptionally smooth surface.

It also provides anti-corrosive properties and excellent adhesion to many difficult substrates including alloy, stainless steel, Zintec and galvanised steel.

SpectroPrime is sold in a 400ml aerosol and is available in nine popular colours:

  • Black
  • Grey shades 2, 4 and 6
  • White
  • Green
  • Blue
  • Red
  • Yellow

2K Primers

Two-component 2K primers are ideal for surfaces that are likely to experience high wear. The chemical crosslinking that occurs during the curing process enhances adhesion and resistance to water, oils and solvents.


A high-build primer combined with 2K aerosol technology, Pro2KPrime can be applied to a wide range of substrates with outstanding adhesion and sealing properties.

It is also very quick-drying and offers great build.

Pro2KPrime is sold in 200ml and 500ml aerosols, both equipped with the unique Vari-nozzle that gives the user a choice of spray pattern for flexibility.

4:1 Primer Filler

This is a high-quality, versatile 2K acrylic primer that offers excellent adhesion to a range of substrates including difficult plastics such as PP, PE and ABS.

4:1 Primer Filler offers rapid drying time and can be applied wet-on-wet. A lid and paddle can be added to the tin to allow for easy dosing and automatic mixing of your paint scheme.

Available in white, black and grey, 4:1 Primer Filler is sold in 1.25-litre and 5-litre kits.

Zinc-Rich Primer

Zinc-rich primers are formulated for refinishing OEM-plated zinc-coated steel car bodies.


This is a quick-drying zinc primer with excellent adhesion, providing lasting corrosion prevention.

ProZinc is sold as a 500ml aerosol.

Alu-Zinc Primer

Alu-zinc primers are formulated for refinishing OEM plated aluminium car bodies.


ProAlu offers excellent adhesion to aluminium, great drying time and a highly corrosion-resistant finish.

Supplied with 2 different nozzles, including the unique Vari-nozzle with its choice of spray pattern for flexibility, ProAlu is sold as a 500ml aerosol.

Epoxy Primer

A 1K epoxy primer is a good all-rounder that doesn’t require the premixing of 2k primers.


ProXL 1K epoxy primer is quick-drying, adheres superbly to bare metal and contains active rust-preventing pigments. It is also suitable as a welding primer and can be used wet-on-wet.

It is sold as a 500ml aerosol supplied with 2 nozzles, offering different spray patterns.

Weld-through primers

Weld-through primers are applied to prepared metal surfaces before they are welded. During the welding process, the weld-though primer liquefies and galvanises the metal around the weld, protecting the metal against future corrosion and providing permanent rust protection on the inner edges of the welded metal pieces.

All ProXL weld-through primers are compatible with SPOT, MIG and TIG welding

ProWeld Zinc Weld

A quality zinc welding primer, suitable for repairing damaged galvanised parts as it provides outstanding corrosion protection and is resistant to high temperatures as well as petrol, chemicals and weather.

It is sold as a 500ml aerosol supplied with 2 different nozzles for a choice of spray pattern.

ProWeldC Copper Weld

A fast-drying copper welding primer, ProWeldC offers excellent conductivity and high adhesion to metal substrates.

It is sold as a 500ml aerosol supplied with 2 different nozzles for a choice of spray pattern.

UV-Curable Primer

UV-curable primers drastically reduce the time and energy required to prepare for over-coating. With performance equal to many 2k primers, they are more environmentally friendly (as they contain no isocyanates) and any unused primer can be returned to the tin.


This ready-to-use primer has a curing time of only 60 seconds, making it the fastest-curing aerosol UV primer currently on the market. Drying time depends on the strength of the UV light source used but once dry it is easy to sand.

ProUV is sold as a 500ml aerosol.

We hope this has clarified the differences between the many types of automotive primer, but if you would like to more information, advice or details on stockists of ProXL primers and other automotive refinishing products, contact us on 01634 823900 or via our online contact form.