How to Polish Glossy Black Plastic Trim


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Glossy, piano black plastic trim is usually found in the B pillar section of cars between the front and back doors.  But it can be found anywhere on a car these days. 

Its scratches unbelievably easily.  In fact if you look at brand new cars in a showroom they look scratched too.  So what can be done?

A polishing machine will give the best results by far.  And if you can get your hands on a machine with a 3″ backing plate, even better.

But I have been happy with the results with a 6 inch machine too.  Just not as perfect as 3 inch.

By hand the best you will achieve is removal of  stains and oxidization.  But you will greatly boost the blackness and gloss levels too.  So if you don’t have a polishing machine you should try this before you buy one.

Polishing glossy plastic trim with a polishing machine

Make sure the pad doesn’t generate too much heat.  This is the main thing to look out for.  So keep the pad moist and the speed down.

  • First wash your car and clean the area with Gyeon Prep or Carpro Eraser or any IPA panel wipe.
  • You probably don’t need to use a clay bar on plastic trim.  But if it feels tough to the touch it will benefit from a fine or soft clay bar.  Note that the clay bar will add even more scratches.
  • Most polishing compounds will stain rubber.  Also, rubber particles will get stuck to the pad and scratch the glossy plastic.  So the rubber trim around the black plastic you are polishing needs to be taped up.  
  • Any good pure cutting compound will do.  Don’t use one that has glaze or wax in it.  Sonax Cutmax would be perfect as it doesn’t dry out or cause dust.
  • A medium pad should do it.  An orange pad form Chemical Guys would be ideal.  You probably shouldn’t use anything harder.
  • Your goal with the compound is to remove as many scratches as possible.  You will almost certainly have a haze on the plastic when you are done.  If you don’t see a haze, good for you, you are done.
  • If you see haze you should follow up with finishing polish.  Ideally a pure polish is needed and not one that contains any fillers.  Faster arm movements are a good way of keeping heat down.
  • You should only need to do a few passes with the soft pad and polish.  If you do more than that you might cause more haze.

Polish plastic trim by hand

You can greatly reduce the swirls and oxidation on black plastic trim by hand too.  But you won’t restore it to a mirror finish without a machine.

  • For light scratches, you can get good results using Meguiars Ultimate Polish.  It also contains glaze that fills in some scratches and boosts gloss.  It will remove oxidation stains too.
  • Use a microfibre sponge or a microfibre cloth and work in small circles.  Test a small area first to see how much work is needed.  There is no real point going side to side or up and down.  Circles are where it’s at.
  • If you have deeper scratches or heavy staining, use a simple over the counter compound like Meguiars Ultimate Compound.  It’s got enough cutting power for deeper scratches and older plastic trim.
  • You can follow up with a Meguiars Ultimate Polish to boost the shine.
  • You might be tempted to spend lots of money on a polishing machine and pads and compounds and polishes.  But the truth is that your glossy plastic trim will just get scratched up again in no time.  So doing it by hand is absolutely fine and does a really good job IMO.

Will ceramic coatings protect plastic trim?

No, not in my experience. 

Will a vinyl wrap protect plastic trim?

Yes, this is probably the best way to protect glossy black trim.  

Will wax or sealant protect plastic trim?

Nope.

Best way to protect plastic trim

  • Try not to touch it.  When you open and close your door do you touch it?  Sometimes it looks like its face cream or makeup that’s causing the staining.  
  • Dont scrub too hard when washing and drying.  Just one pass with the wash mitt should be enough.  And when drying just pat dry.
  • Get vinyl wrap for your B pillars.  You might be able to find one for your own vehicle using a service like https://www.rvinyl.com/.  I haven’t tried these but they seem to have happy customers. 

Conclusion

BY MACHINE : To remove swirls and scratches from glossy black plastic trim you’ll need a polishing machine to get the best possible results.  It usually takes a two step approach with compound first and finishing polish with a very soft pad after.

BY HAND.  You wont be able to achieve a mirror finish by hand in my experience.  But you can really clean it up and make it look great using a microfiber pad and some compound like Meguiars Ultimate Compound.

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