Robot and mecha kits are unusual in the modelling world, most of them arrive pre-coloured to roughly match the finished scheme, moulded in the correct plastic rather than a single neutral grey. That is great if you are happy with the stock scheme. It becomes a real obstacle the moment you want anything different, because you are no longer painting a neutral surface, you are painting over an existing, often dark, colour, and thin paint just shows the plastic straight through.

This is the exact problem ONECOAT was built to solve, and it is worth understanding why it works rather than just taking it on faith.

Opacity comes down to pigment load and particle size, not marketing claims. A thin, glaze-style paint is deliberately formulated with less pigment so colour can be built up gradually and blended smoothly, ideal for highlights and transitions, bad for basecoating over dark plastic. A basecoat-style paint like ONECOAT is formulated the opposite way, high pigment density, designed to go from wrong colour to right colour in one pass.

That is also why swapping the two ranges' jobs backfires. Using a glaze-style Layer colour as your only basecoat means fighting patchy coverage for three or four coats, and using ONECOAT for fine blending work wastes its main strength on a job it was not built for.

• Most kits need no primer at all with ONECOAT. That is the point of the range.
• Wipe down first regardless. Isopropyl alcohol or warm soapy water removes mould-release residue, which affects adhesion no matter how good the paint's coverage is.
• Prime only the awkward surfaces. A very glossy part or a dark chrome-style finish benefits from a light coat of Undercoat Grey or Undercoat White first, an option rather than a requirement.

ONECOAT performs identically well through either method. Hand-brushing benefits from slightly thicker paint straight from the bottle and a soft, even stroke rather than scrubbing. Airbrushing benefits from a small amount of Airbrushing Thinner to get the paint flowing cleanly through the nozzle without losing opacity. Neither method requires more than one coat over correctly prepped plastic.

If a colour needs to cover a large area regardless of what is underneath, reach for ONECOAT. If a colour needs to blend, glaze, or pick out fine detail, reach for Layer. Match the paint to the job and the three-coats-to-get-full-coverage problem mostly disappears on its own.