The boxster, in fact all my car models are painted the same old tried and tested method I’ve used for a long time.
I always prime the plastic first using a good plastic lacquer primer. Halfords sell good plastic primer, as it will protect the plastic from melting, as once I’ve primed I then use automotive lacquer paints or sometimes Tamiya TS lacquers, and lacquers can sometimes etch or even melt plastic. Tamiya Lacquers are formulated to work directly on styrene, but I always prime anyhow.
I sand the primer with good automotive 1200 grit, wet n dry. This means the primer has small scratches, but it’s smooth, allowing the lacquer paint something to bite into, but not etch the plastic, as the primer gives a good barrier against the hot lacquer solvents.
Once I’m happy that the primer is smooth and even I then wash and allow to dry. I also use a pre coat of white or red etc primer for lighter colours. Yellow for example needs a cream primer, white needs white, whereas red needs a pink primer. You need to gauge the paint you are using. Yellow for example is less opaque then black. Black covers anything, so grey primer is fine.
Apply two – three mist of top colour. Allow to dry, then a slightly wetter coat. Allow to dry, cut back with 1500 to smooth the orange peel out. Finish with a further two wet coats. Last coat so wet it almost runs. Then allow to cure off for about a week. (this does depend on type of paint used, drying conditions etc. Auto Lacquer dries within a day, but takes a week to fully cure off, Tamiya TS paints take a little longer, Acrylic nearly a month to fully cure and enamels forever)
Now with the paint cured, you need to fully inspect the final finish. Look for orange peel. This is where you need to decide, do you need to flatten the paint with 2400 grit or can you get away with just using a good compound polish and then wax. It’s hard to explain, but to get a mirror finish you need to ensure the surface is smooth like a mirror, as any dimple in the paint will reflect the light at the wrong angle, and reduce the shine. You get the surface smooth, by sanding and compounds, but
too much and you run the risk of sanding to the primer.
and tend not to bother, I just do a bit of dirtying up with a HB pencil and my fingers which looks 'okay' for light dirt smearing but is no use at all for panel lines. If you could tell us what paints you use, what oils/paints you use for the wash, and what sort of dilution, that would be really helpful!
