Basically I don't know anything about painting or paint prepping. I have a front lip(urethane), stock sideskirts, and the side moldings on my car that I would like to paint match to frost white. What kind of prep work has to be done on these pieces?

I'm asking because I heard that you are not supposed to sand urethane before you paint but I am not sure. Any help will be appreciated. Thank you.

 

I haven't heard that but I'm no professional or anything but I think you can just sand it....at least that's what I've done before and it turned out fine. Use 400 grit b4 painting You might wanna get some more feedback before doing anything though

 

You better sand that **** if you want the paint to stick to it dude. First thing you do is go the store, by you some wax and grease remover, some 320 and some 400 grit wet or dry sandpaper. Then you come home and take the wax and grease remover and clean the hell outta the urethane. Try not to touch it much at all with your hands because of the oils. ( i recomend some latex gloves) Once everything is very clean grab a hose pipe and the 320 grit and begin to sand. Make sure you sand with your palm and not your fingertips. Do the whole thing with 320 tills its nice and dull. Then go over it all with the 400 making in perfectly smooth. Let dry and then wipe down with the wax and grease remover again and youre ready to spray.. Good luck.

 

You should also make sure that you get the proper primer that is specially made for Urathane. There are differenet kinds on primer and metal primer will not work too well. Urathane has pores in it like your skin which hold in the oils. You must get a primer which will allow the pores to open up and get in there. If you do not use the right primer you will get peeling and cracking on the paint because it is not in pores. This will happen more in climates with drastic weather contrasts like Canada or the Northern US. If you live in a place like Cali or FLA then it will last longer but it will still eventually crack and fall off.

I know this from experence when I was given a WW front bumper for a 88 Civic that I was working on. I just sanded and used normal primer on it and in about 4 months when it started to get cold up here in Canada you could see that the paint was coming off from the bumper and by the end of the winter about 40% of the bumper had bee completely peeled back down to the black. When I re did the paint with a urathane primer the paint lasted and it still is there today(about 2 years later).

CRX Forum

 

Ok thanks guys for your help, that's exactly what I needed to know. Sorry about the dumb questions but I've never dealt with paint before.

Thanks for the help.

 

I was wondering also for the side moldings, do I use the same steps for preparing them? Can I do it on the car or should I take them off?

 

I really don't reccommend sanding urethane or abs/plastic products. What happens is that the fibers start to thread out if you sand it too much. Secondly if you sand you will have to try to fill the scratches with primer so they don't show in your base/clear after being painted.
If you are inexperienced my reccommendation is to take it to a shop and have it done professionally. Check to make sure that shop has the experience, a lot of places don't like to do urethane etc. because of the massive amounts of prep time.

The best thing to do is to go to an automotive paint supply store(not PepBoys etc.) and get their urethane or plastic prep products. If you notice when you run water over your parts the water will bead up. This is the mold release agent. You have to get all this off or your paint will just flake off(sanding won't necessarily get this off). You take a grey scotchbrite pad and scrub the parts to be painted(use with water). You want to scrub until the water just sheets off the product and doesn't bead up anywhere. After this you can prime and paint. Make sure there is plenty of flex agent in the base and clear for the front lip. This keeps the paint from flaking when you scrape. See no sanding needed. Good Luck and Sorry so long.

 

That's not too long, its exactly what I needed to know thanks.

 

okay take it from an EXPERIENCED guy here!!!!! You DO NOT need to sand, but instead scuff with a 3M RED grade scotch pad. You DO NOT use Wax and Grease Remover on plastics/urethanes because this opens up the pores, instead use a plastic prep cleaner which you can get from your local autobody supply store.

First wash the parts with soap and water,
then use the cleaner,
then scuff,
use the cleaner again,
tack cloth it to get dust off,
use an adhesion promoter,
use a primer Sealer right before applying base color and clear.(make sure you use a flex additive in the primer sealer....its not neccesary to add it in the base or clear if you are using a Urathane Paint System)

Primer surfacer is NOT needed because these primers are only used when you have imperfections that need to be wetsanded straight.

People who respond when they don't know what they are talking about are just ignorant Because this not only misinforms the person/s needing help, but it confuses them as well. (I did not read everybody's post so sorry if I'm wrong).

My techs are based upon "Professional" qualities, while most of these people's techs are just "back yard" quality jobs. (Again I did not read everybody's post so sorry if I'm wrong).

It's up to you now to decide which tech to trust for the longest lasting paint job.


[Modified by tnbigdawg, 1:52 PM 1/15/2003]