Repairing and Painting Plastic
Repairing and Painting Plastic
Plastic is one component that makes up most of the inside of a vehicle and can be one of most difficult to repair and paint. That is if you don't replace the piece first. To be really honest when it comes to some of the plastic trim pieces, door panels, and kick panels its cheaper to replace the pieces then to repair them. But I do mean some, there are many instances where a little heat in the right spot or some dye applied to the surface can hide or repair an imperfection and save from replacement and that's what I'm here today to talk about repairing and painting those cosmetic repairs on plastic interior panels.
Let's say we have a scratch down the door panel and it's deep enough to feel with your finger nail. This type of cosmetic repair can be fixed with a heat gun, a matching grain pad, dye, and some finesse. The finesse is a big thing too. You can make a bad thing a really bad thing really quick if your not careful.
When heating plastic to repair a scratch you have to melt it to almost the liquid stage and press your grain pad into the plastic very gently but firmly to achieve the right effect. If you press to hard you will make a dent in the panel and not enough you won't get the grain imprint in the plastic like you want and you won't melt the scratch together either. You melt the plastic like I said almost to the liquid stage.
First things first don't sand the fuzzy's off or try to sand the scratch down prior to melting, use the plastic that's there to melt back into the scratch where it came from.
I will usually heat and press a few times, basically melting a little at a time. It also helps to cool the plastic with a chill bar after a couple of attempts so not to stretch or dent the plastic. Learned that one the hard way on a rear quarter of an Expedition. When there is nothing behind the plastic to support your melt then the plastic will push in if you don't take your time and cool things down between attempts.
Cooling also helps to set the imprint so when you go to remove the shinny spot, which I'll talk about in a minute. you won't distort or even loose your grain because the plastic is still to warm.
When you press the grain into plastic try to remember not to use your thumb if you can, use the grain pad laid in your palm, this will help also to cut down on denting the plastic panel. I have a little rubber squeegee I use at times to lay on the back of the grain pad to give me a level surface to press on.
Now once you have melted the scratch back into the plastic you'll be left with a shinny spot in the plastic where you have melted it. To get rid of this take a scotch brite pad and scuff lightly over the area, not to much or you'll distort your fix. Once you have scuffed the area a little extra and the area's around it, it will need to be cleaned thoroughly before dye is applied.
Painting plastic is just that applying a coat of paint over the top, some think you can actually "DYE" plastic. Well unless you have a way to penetrate the surface of the plastic then your only painting the surface and I don't know of any penetrating paint for plastic. But just out of habit you'll hear me say dyeing plastic too here and there.
So... you have to get the plastic as oil and dirt free as you can or the paint won't stick, period. When your prepping plastic use only a fine grade sand paper or a scotch brite pad to scuff the surface. If you use anything heavier in grit then you will see the sand marks or scuff marks guaranteed. I use my special prepping solution for all my prepping but I have used wax and grease remover and lacquer thinner but be very careful with lacquer thinner and plastic, if you let it set to long it will melt the plastic or even distort the grain so really wax and grease remover or my prepping solution is all that is needed. If that's not handy then dish soap and warm water.
Applying your paint can be done by either spraying or wiping it on. I usually spray everything except for my primer. I use a wet paper towel to apply my sticky primer or grip base, whichever you may use with your water based paint. Always apply a primer or adhesion promoter prior to painting plastic. It will make your repair last a lot longer I promise.
Now as part of repairing plastic you may come across a piece that is broken slightly and an actual plastic repair can be done to save a piece without replacement. This is accomplished by what you call a plastic welder. Some of you guys probably already have one and use one on a daily basis to repair bumpers and such. This is one tool that is a must when repairing a broken piece of plastic. Super glue won't hold and epoxies can be a mess and probably won't hold either and that's where a plastic welder comes in. It does exactly what you think it welds the plastic back together by melting new and existing plastic into the crack.
I've used mine a few times and have had great success.
Now like I said before mending a cracked piece of plastic needs to be cost effective. If the piece can be replaced for cheaper then you can fix it for, then replace it, don't spend all afternoon fixing a crack in a piece of plastic that someone could have bought at a junk yard or new for cheaper. Heck there have been times when I still get the job because a replacement part needs to match, so I paint it to match. A lot more cost effective.
One other thing not all plastic pieces can be repaired and look right, it's just the nature of the repair. Your not going to make every plastic repair look absolutely prefect. Sometimes it's the grain pattern in the plastic or just the plastic itself. If you can hide it well then go with it but if it just looks as bad as it did when you started you probably need to replace the piece.