How to prep and paint fibreglass/plastic bumpers

**Dyldo** · 16-03-2011, 07:47 PM

Dubbers

Hopefully this will become a sticky for anyone who wants to do DIY bumper prep and paint. I have acquired a set of bumpers that have been described as being "semi-primed Glass fibre reinforced plastic" and I'd like to take a good crack at prepping and painting them for fitment.

My FIL used to spray cars a few decades ago, so he should have good technique and keep me on the straight and narrow. he's done about 50 cars, maybe more.

My BIL had engaged two of his mates (one a panel beater and the other a spray painter) to come over on their weekends to work on his 'Stang but they haven't been around in ages. Long story short, I can use all their gear such as sanding blocks, air-driven sanding gear, and of course their gravity-fed guns. I don't know what model but they have all the different spray heads for clears and primers and different paint types so we should be set.

I imagine I need to set up a quasi-booth with heaps of plastic sheets suspended from a well-lit garage but we have heaps of space.

So i guess now i just need to ask a few questions:-
- what paint type should i use?
- do i need to add that flexi agent/rubberiser to give the paint some flex to avoid cracking?
- is there a particular brand of paint or spray head style i should use?
- How long should I allow for the job, assuming I have done a good job with prep?

**Dyldo** · 20-03-2011, 09:22 PM

nobody's got anything for me? no tips? no pointers? Just jump right in and swim?

**Jarred** · 20-03-2011, 09:55 PM

I'm not a professional. But, this is my advice, do with it what you will. I've had a little bit of a experience with spraying cars & paint work in general, but it is something that interests me.

I'm pretty sure there is a specific primer for plastics & fibre glass, so the first thing I would do is get some of that and shoot the bumpers and then go from there. Avoid using bog, as it's prone to cracking, when flexed etc. I'd use fibreglass reinforced filler if I had to fill some holes.

As for specific paint products, I'd go to my local paint shop, and tell them what I want to do. If you're willing to learn, I've found most will be willing to spend a little time explaining things, and giving that little extra bit of help. They'll also be the ones who's advice I'd be taking on paint selection etc.

Apart from that, just jump straight in. How ever long you think it'll take, double it. If you limit time, you'll rush your self, but if you take your time, and have some fun, hopefully the end product will show that!

Oh and keep everything super SUPER clean. Even before you start ANY prep, make sure the bumpers and cleaned with wax and grease and make sure all through the progess it's always wiped down with wax and grease and tack clothed etc. Minimise dust that's around I'm sure your FIL will fill you in on all that though.

**Dyldo** · 20-03-2011, 10:43 PM

man, just what i needed. cheers. just some common sense but always good to read it from someone else.

**D3bb4** · 25-03-2011, 12:45 AM

I do paint... and you do need a bonding agent/adhesion promoter for plastics and fibreglass.

Backyard work; you wanna be using acrylic, or you wanna be letting a shop spray it in 2k. For bumpers; I'd suggest having them done in 2k. Acrylic is a thermoplastic, and is basically a much softer paint than 2k is. 2k is far more resistant to stone chips, hence the suggestion.

Anyways; don't spray 2k at home. It magnifies imperfections due ot higher build, and it could literally kill you....

Acrylic is easier to use also, and more suitable for home use. Pick yourself up a spray mask from supercheap, scotch brite the panel/lightly scuff it, buy your primers and paint, and have fun. Then buff it later for a mirror finish... and dont forget to put plenty of layers of clear IF it's metallic.