Good write up by WFO. I have also used Bulldog for painting plastic, it's a great product!
Here is the basic process I use for painting.
-Sand everything down smooth. If the existing paint has multiple layers, sand down to AT LEAST the first layer. Most oem paints or primers are adhered really well to the substrate material. Exception probably being mid 90's white Kawi's. If there is any peeling or chipped paint those areas will need sanded down to the substrate and feather edged out to the surrounding paint layer. If it makes you feel better you can sand ALL the paint off, but it really is not necessary.
-Finish initial sanding with 120 grit.
-BODYWORK rough in stage......no primers yet. This is the time to fill any gouges and perform any glasswork you may need to do. You can fill with a thickened epoxy resin, OR a product like Duraglas.......which is a waterproof, glass reinforced body filler.
-Block out all the bodywork and finish sand with 180 grit. Now is when you will blow/vac all the dust off and wipe down with a "prepsol" or similar. Some guys use reducer, thinner, grease & wax remover, whatever floats your boat.....so to speak!
-STOP........primertime! At this point the bodywork looks real good and ALL the products used have reached their FULL CURE TIME. Now we need to seal it all in with a couple coats of 2k epoxy primer. DO NOT SKIP THIS STEP! The epoxy primer is needed to keep all the underlying bodywork sealed from the elements. It will also really "grab" the substrate and give any other topcoats a solid base to hang onto.
-Wait until the epoxy fully cures to scuff sand with a grey scotchbrite OR MAYBE NOT.......follow the paint manufacturer instructions for topcoating the epoxy primer!!!
-Next step is your high build urethane or polyester type primer......filler-primer. I've learned to like the roller method on my high build to get nice thick coats without loss cause of overspray. Or you can spray it, it will require a larger tip than paint. Something like 2-2.2mm.
-After the high build primer is cured, take some sandable primer in a spray can of a CONTRASTING COLOR and mist over the ENTIRE project. This is your "GUIDE COAT". As you sand it will give you visual representation of any high/low spots, dips, divots, pinholes, etc that you wouldn't see otherwise.......trust me, there WILL be some!
- IT'S TIME FOR A BLOCK PARTY!! And I mean block sand. I prefer the foam "soft" blocks, but sometimes a paint stick or PVC pipe comes in handy for certain areas. I generally do this WET with 220 grit. It helps keep the sandpaper from clogging up.
-Body touch up. Any of those problem areas that showed up after block sanding would now be touched up. A glazing spot putty should be all that's necessary, or maybe even just some more high build primer. Either way touch areas up, high build primer, block sand.
- RINSE & REPEAT, the previous step until the body is LASER STRAIGHT!........or not, if you like a paint job that's waving at everybody like it's a float in the Thanksgiving day parade!!!
-Final sealer primer.......YES, more primer! This step is done to seal in everything underneath right before paint so there's no blotchy spots or discoloration through your fancy new paintjob. You can buy this in a spray can. If you have some epoxy primer left you can also thin it down so it sprays out like paint as use it as your final sealer.
-Wet sand AGAIN! 400 grit wet sandpaper. You can soft block it or fold the paper over and do it all by hand. DON'T use much pressure. At this point the whole project should be straight and smooth so we're just basically scuffing the sealer primer to give the paint good bite.
-Wash the project, blow out crevices with compressed air, prepsol wipe down, and wipe down with a tack cloth.
-Mask off any areas you don't want paint on. Prepsol wipe and tack cloth again.
- WOO-HOO!!! PAINT TIME!!! Whatever makes you comfortable here. Single stage is usually easier for the beginner cause it can be wetsanded and buffed and touched up pretty easily. But DON"T BE SCARED of base/clear or even 3 stage stuff. If you screw up the base color it can be wetsanded out, then scuffed down and still touched up BEFORE clear. And if you have orange peel or runs and sags in your clear it CAN ALSO be sanded and buffed out! Just keep in mind that a nice base/clear will run you about twice as much money in the final paint .
-Final step is the "cut-n-buff". WAIT until the paint is "dried in". I like at least a few 80* or more days sitting in direct sun. The paint tends to shrink as it dries and if you cut-n-buff too soon it can shrink more and then you end up doing it again. This requires some practice as you can "burn" through the paint with a buffer by running it too fast or staying in one place to long. You don't NEED this final step but this is where that mirror paint look comes into play. If you're worried, pay a professional. If not, CARRY ON my wayward son!! Again, I like the soft blocks here with wetsanding. Depending on how the final paint laid out will determine what grit paper you need. Usually I will try 1500 grit first and see what happens. If you have some dry spray or heavy orange peel, you may have to start at 1000 or even 800 grit in those areas. Then work up to about 2000 grit. I feel like anything above 2000 is a waste of time because the right compounds and buffing pads will work it out above that anyway.
-Finally......you're done! RESIST THE URGE to wax this beauty! We don't want to trap any remaining solvents that are gassing off. DO NOT wax your new paint for 6 months!
I hope this helps any newbies with the confidence to tackle a paint job. It's not rocket science......YOU CAN DO IT!!!!
Maybe somebody could sticky this as a paint how-to.
