Hey fellas.
Im gonna colour code my punto side strips and I was wondering which colour primer I should use. My Punto's metallic Calypso Orange, paint code:571. I was gonna stick with white primer but I know you can get red, yellow, etc.
MSH
My first concern would be to use some type of special plastic primer, which is usually thin and clear (no colour). It has to be applied very thinly, or it will run. It can be difficult to see how thick you have applied it (because it has no colour). The purpose of the plastic primer is to dissolve slightly into the plastic so as to give a good 'key' for the paint (normal primer may just flake off).
I think then I would just spray the colour straight over the plastic primer, unless you want to then use a high-build primer to smooth the surface (you can't really get a high-build primer in an aerosol can, or if you do, it's called 'spray putty').
The primer colour often relates to its rust-preventing ability (e.g. red oxide, grey zinc) although I admit there are special-coloured ordinary primers for use with really light-coloured top coats. Obviously rust preventing is not an issue here, so I think you could just go with light grey/white - but I thought I'd mention the (official) need for plastic primer. You may get away without - in this case may I suggest applying the primer and paint in a *thin* coat, only a dusting of primer and just enough colour coat to get the correct colour. I've found that cracking on plastics is more likely when the paint is thick.
Also (contrary to what you might think) paint chipping is more likely to be a problem if the paint coatings are thick, especially if there is that spray putty involved. Spray putty has another problem too - it shrinks. This applies to all aerosol paint to some extent because they have a high solvent content (in order to get the paint to spray nicely from a pressurised can). The more paint goes on, the more shrinking occurs, as the solvents slowly dry out. If you have sanding scratches under the paint, they may reappear after a month or two. Ditto for any texture in the plastic. There are three possible solutions: 1) leave the spray putty/thick primer a month to harden before 400-grit sanding and top-coating, 2) use non-aerosol 'professional' two-pack paints and spraygun, or 3) as I suggested above, don't use spray putty/thick primer
I forgot to mention that before you do anything else, make sure you rub the plastic strips really well with a clean rag soaked in wax-and-grease remover (e.g. 'Prepsol', from paint shops), wear gloves unless you want to see if you get cracked/blistered skin
This step is really important whatever type of paint you use, because the plastic will probably have silicones from 'back-to-black'-type products used in the past. If not removed, these silicones will ruin any coating you apply; you'll see 'fish eyes' - basically 'craters' where the primer/paint refuses to stick to the plastic (yes I have had these problems myself
)
Sorry this info is a lot more than you were asking and please don't be offended if you already knew all this. Hope it helps and doesn't put you off the customising, which sounds promising - I like that orange!
-Alex
