I just wanted to drop a warning in here for any inexperienced painters in the community regarding a particular brand and/or type of plastic primer or as it may sometimes be called, "adhesion promoter". The brand that I'm warning you against in particular because I have previous experience with it is Holts Duplicolor Plastic Primer. Tag number on the can is "L118". This stuff is available anywhere you can buy Holts Duplicolor automotive paint, like auto spares shops, body repair stores etc etc. I've only ever seen it with a white lid on it marked "Plastic Primer" and when you spray it you'll notice it is clear, like lacquer. Anyone who has never used this stuff will tell you it's the correct product to use on bare plastic. I'm telling you it's not. This stuff is absolute garbage and you should never use any sort of "adhesion promoter" or plastic primer that is clear like this stuff. Just to prove a point, I shot a thin coat of this over an Antec Three Hundred bezel that I spent about an hour prepping this evening. I'll take some photos of it tomorrow to show you exactly what happened once that coat dried. The primer comes out of the can like water, and does not adhere to the plastic. This was plastic that I had keyed (sanded) to remove the Antec factory paint from with 600 grit wet & dry paper, then thoroughly cleaned with panel wipe before application. Plastic primer is supposed to "etch" the surface of the plastic very slightly and give you a good smooth surface to apply standard primer to before the colour coat. This particular primer pools and runs as soon as it makes contact with the surface of the plastic. The thicker you lay it on, the more it runs. I just used a very thin coat this evening and it still ran. There was no adhesion to the plastic whatsoever. Because I only put a light mist on, it'll only take me an hour or so in the morning to scuff it down again with some 600 grit paper and apply the proper plastic primer, which is a paint that comes out of the can as a visible colour - usually either red, grey or white. This type of plastic primer does what any etch primer is supposed to provided you prep the surface of the plastic properly first. It adheres to the surface immediately and applies very easily and uniformly provided there are no surfce contaminants in the plastic prior to spraying. Always use two thin, even coats of this type of primer on your plastic parts before applying the build primer and eventually the top coats of colour and lacquer. Don't ever use the clear type of plastic primer or adhesion promoter because it will ruin the prep work on your plastic parts and you'll have to start over. I hope this is helpful for some people. The first time I came across this stuff was a couple of years ago and I was horrified at how bad it was. Maybe it's designed to be used on a different type of plastic, but back then I tried it on keyboard housings, case bezels and even an engine cover and it had the same effect on everything. Just stick with the proper plastic primer paint
It all depends on the polymer in question, the automotive industry tends to use Polypropylene and Polyethylene, so the solution should attack both these materials, thus changing the surface finish. Now i don't know what Antec used for there case front, but i do know that the Holt plastic primer does in fact work on car plastics as I used it in the past to colour code a replacement wing mirror and a friends bumper. There is a good chance that Antec went the route of ABS which could be a good reason as to why the primer didn't work, however i would have expected Antec to go the cheap route and use PP or PE. Of course it doesn't beat a good painter primer, however when trying to keep the paint layers as thin as possible it works a treat.
The Antec bezel (most computer bezels and bay covers in fact) are injection moulded ABS. The primer is obviously designed to etch only Poly plastics, whereas good old paint based plastic etch primer will, in my experience, work on just about anything.
