The Primers, Undercoats and Lacquer section covers the supporting paint products that turn a panel respray or a complete bodyshell refinish into a properly engineered coating system, alongside the dedicated synthetic engine enamel range in original MG colours, Red, Black, BMC Green, and MGC Green, for engine-bay refinish work on the B-series, A-series, C-series, and Rover V8 applications. The principle behind a good paint job is that each layer is chemically compatible with the next, the etch primer keying into the bare steel, the high-build primer keying into the etch, the colour coat keying into the high-build, and the lacquer keying into the colour, so mixing brands or systems risks layer-to-layer incompatibility, and the products in this section are matched chemically to the body paint range.
Etch & Zinc Primer for Bare Metal
Etch primer is the first coating applied to bare-metal panel work, its zinc-phosphate or zinc-chromate active component etching into the surface to create a corrosion-resistant chemical bond that ordinary primer cannot achieve, suitable for both the steel bodyshell panels and, on the later cars, the aluminium engine and gearbox castings. Aerosol etch primer suits the small touch-up and patch work that follows a panel repair, while tin etch primer is for full-panel work, and in both cases it is applied to clean, degreased, freshly-prepared bare metal, allowed to cure, and then top-coated. Zinc-rich primer provides a higher level of corrosion protection than standard etch primer, using zinc particles to create a sacrificial barrier that protects the underlying steel even if the surface is subsequently chipped or scratched, particularly well suited to structural areas, sills, floor sections, and spring hangers where long-term protection against rust-through is the priority.
High-Build Primer-Undercoat
High-build primer-undercoat is the next layer in the system, applied over the cured etch primer, or directly over a sound existing primed panel, to fill small surface imperfections, key the panel for the colour coat, and provide a uniform base for the topcoat. It can be flatted back with wet-and-dry paper between coats to give the panel a glass-smooth surface that the topcoat will flow out across, and rushing this stage is the most common cause of a disappointing final result, as imperfections in the surface beneath will always telegraph through a gloss finish. Two-pack high-build primer with a separate hardener gives the strongest cure and the best filling properties and is the workshop standard for serious refinishing work, while single-pack aerosol primer is suitable for touch-up and small repair work.
Engine Enamel
Synthetic engine enamel is available in the original MG engine colours, Black, Red, BMC Green, and MGC Green, for refinishing the engine block, cylinder head, and ancillary components during a rebuild, the correct colour for the MGC engine being MGC Green, a pale silver-grey-green distinctly lighter than BMC Green. For engine applications a heat-resistant primer is essential, as standard automotive primer will discolour and flake within weeks on a running engine, and surfaces should be thoroughly degreased, lightly abraded, and primed before the colour coat, since engine paint applied to a poorly prepared surface will flake and peel as the engine heats and cools through its operating cycle.
Topcoat Lacquer
Topcoat lacquer is applied over the final colour coat on metallic, pearlescent, and certain solid-colour finishes, providing the gloss, the UV protection, and the depth of finish that the colour coat alone cannot achieve, and is matched chemically to the colour coat so a workshop using the matched products through the system gets a fully-integrated finish. On metallic and pearlescent finishes a lacquer coat is essential to achieve the correct depth and appearance of the colour, while solid colours can be lacquered for gloss and protection but do not require it. Lacquer is supplied in aerosol presentation for touch-up work and in tin presentation for full-panel work, the workshop application typically being two or three coats with proper flash-off time between layers to avoid solvent trapping that causes bubbling and orange-peel texture.