I am currently getting ready to spray some fiberglass panels for an 18 wheeler. The fiberglass hood is being purchased new from an aftermarket dealer. Once the hood arrives will I need to prime it or can I just sand it with some 1000 and spray on? I will be using acryllic enamel by the way.

Thanks,
jchiesa

One of the things is that new fiberglass parts can have mold release wax on them so you need to scrub that part with ammonia and hot water till you are tired of scrubbing..

Then wipe it down with acetone to make sure all the wax is gone..

Watch for pinholes in the part..sometimes in spite of the best efforts there will be little air bubbles in the mold..to fix this use a primer surfacer..then spray it out with whatever you normally use in your shop..

OMT

Thanks a TON! I will wash it as you said before anything else. If the surface is already smooth, should I still sand it? I know that sanding promotes adhesion but I also don't want to muck up the job before I even spray.

Thanks again!

It will probly have a smooth gel-coat finish which does need scuffing or sanding 400-600 before painting IMO. On the hood,It would be worth while to long block it before you shoot paint. Some imperfections could be in it that the naked eye won't see and as soon as you paint it will stick out like a sore thumb.My 'glass hood on my Ram had this happen and the upfitter had to replace the hood a year later at his expense. I'm not a pro on 'glass and I'm sure there are other ways to skin this cat so, hang loose and get some more oppinions before shooting a acrylic enam. and having to redo it.

Paint will no tstick to slick shiny gelcoat..at least not for very long..Soooo scrub the part with 3M scrubbers or wash and wet sand..whatever you do get the wax off and get rid of the shiny before painting..a good quality primer or primer surfacer will take care of the deal from there and after that it is the normal bc/cc finish..

Properly prepared fiberglass parts are dull (no shiny anywhere) then apply paint..

OMT

I was going to use southern polyurethanes products on my firebird. I'm going to strip everything down and use epoxy on the metal, then 2K urethane, then possibly poly primer and then seal. My question is would I be better off using the same steps on the fiberglass panels or just use 2K urethane? What would you guys do diff on the fiberglass panels? Thanks.

One great solution would be to use the zero rust primer paint together with zero rust prep. You would mix the prep with water, its a phosphatizer and not an acid, this will bring the metal to ph6 and then spray with zero rust. *********** for more information