Why do my pads turn black when polishing certain types of painted plastic?

[95maxrider]

I`ve been wondering this for years but could never figure out what`s happening, so I decided to post up and ask. For reference, this is all happening on a silver 1996 Infiniti I30 with original paint in good condition.

When polishing certain types of plastic, usually the softer stuff (certain bumpers, door trim bump guards) my pads will turn black almost immediately, and no amount of polishing seems to stop it. Use a new pad and it still turns black. Yes, I wash and clay bar the areas before polishing. These parts are not black, they are painted silver. Here`s what I`m talking about (smaller pads only):

https://images.squarespace-cdn.com/content/v1/599600f059cc68e96b469975/1635267229709-HOQAHX735QOZ33T4ZJQH/IMG_3570.JPG?format=2500w

On a similar note, when polishing some door trim I got from a junkyard, I noticed that the more I polished, the more the gloss or shine was reduced. Not that you can see what I`m talking about, but here are the pieces I`m referring to:

https://images.squarespace-cdn.com/content/v1/599600f059cc68e96b469975/1635267148338-K6NMDT9T8JUEWSRRFB5R/DSC08941.JPG?format=2500w

It almost seems like the more that I polish, the more clearcoat is being removed. I can`t think how else more polishing would result in less shine. This coincides with the never ending blacking of the pads. I`m not applying any pressure to my Flex buffer when doing this, and it has happened with both Menzerna and Griots polishing compounds. My pads are Lake Country.

Can anyone explain what`s happening here?

[ShaneB]

A lot of those black plastics like the B pillars and C pillars are not clear coated. So you’re polishing the plastic itself, which is black. Polishing is abrasive so what you’re picking up is material from the surface that’s being removed by polishing

[Stokdgs]

I have corrected scratches on the A, B, C pillars that were black and every other color, on hundreds of vehicles, and never had this happen..

Which Menzerna and Griots products are you using?? What brand and type of pads are those ?

I believe the paintwork on that vehicle may be Single Stage paint, which has little to no clear coat, so you will get the color off on the pads..

What you need to do is Stop polishing, so you quit removing all of the paint...Correct it as best you can and then stop...

You are not going to "polish" through this and it will all stop coming off..

Same with the trim pieces you got - you are removing all the paint/clear coat from them and it is never going to get better.. It is going to get to the end, and then there is no more paint left on them..
Dan F

[95maxrider]

A lot of those black plastics like the B pillars and C pillars are not clear coated. So you’re polishing the plastic itself, which is black. Polishing is abrasive so what you’re picking up is material from the surface that’s being removed by polishing

I`m not polishing black plastics, these are painted silver. So I`m somehow polishing the underlying plastic, but not the paint that`s on top of it? I don`t understand how that`s possible.

[95maxrider]

I have corrected scratches on the A, B, C pillars that were black, on hundreds of vehicles, and never had this happen..

Which Menzerna and Griots products are you using?? What brand and type of pads are those ?

I believe the paintwork on that vehicle may be Single Stage paint, which has little to no clear coat, so you will get the color off on the pads..

What you need to do is Stop polishing, so you quit removing all of the paint...Correct it as best you can and then stop...

You are not going to "polish" through this and it will all stop coming off..

Same with the trim pieces you got - you are removing all the paint/clear coat from them and it is never going to get better.. It is going to get to the end, and then there is no more paint left on them..
Dan F

In the past I`ve used Menzerna Intensive Polish and Final Finish. I now use Griots Fast Correcting Cream and Perfecting Cream. My pads are Lake Country.

The paint on this vehicle is not single stage. Think of it as a 1996 Nissan Maxima. And the color of the paint is silver, not black. This does not happen on any metal surfaces, or on the rear spoiler, which is a different type of plastic.

Agreed, I stopped polishing once I saw it wasn`t improving.

[Stokdgs]

In the past I`ve used Menzerna Intensive Polish and Final Finish. I now use Griots Fast Correcting Cream and Perfecting Cream. My pads are Lake Country.

The paint on this vehicle is not single stage. Think of it as a 1996 Nissan Maxima. And the color of the paint is silver, not black. This does not happen on any metal surfaces, or on the rear spoiler, which is a different type of plastic.

Agreed, I stopped polishing once I saw it wasn`t improving.

95maxrider --

You said this --" when polishing certain types of plastic, usually the softer stuff (certain bumpers, door trim bump guards) my pads will turn black almost immediately, and no amount of polishing seems to stop it"..

We assumed you are working on a black single stage painted vehicle..

There will be no paint color transfer from healthy, clear coat, paintwork, unless you have gone through the clear coat, and are now hitting the paint under it..

The Griot`s Fast Correcting Cream is too abrasive to use on delicate painted areas like A B C pillars, and plastic parts like plastic bumpers, etc..

The Menzerna Intensive Polish is also too aggressive for those areas.. It is a cut of 5 and a gloss of 6..
Aggressive compounds will correct quickly and usually, not finish down really clear and glossy, like polishes do

I would use the Menzerna 3000 Final Finish, or the Griot`s Perfecting Cream only, for the ABC pillars.

In my experiences with these pillars, they are usually scratched by fingernails, which usually don`t do much deep damage, so a nice, mild, polish with a medium cut pad or less cut pad should suffice... You have to just get them good and then stop..

Whatever color paint that is on the pillars is not very thick and will go away quickly; and nothing short of a repaint will bring it back if you take too much off..
Dan F

[bad penny]

Metal flake

[Lonnie]

If you are getting "Black" residue on your pads from buffing black plastic A-B-C pillars, chances are you are also buffing the rubber seals around them and transferring that material to your pads.
To avoid this, you will need to tape off the seals with painters tape. 3-M Blue Pro Painters tape is good or CarPro`s Red Painter`s/detailers tape can be used.
The "problem" is that you will need to use a 1/4" wide tape and this size may be difficult to find these days. You may find this size at an auto paint supply store.
You can use 1/2" wide more commonly found at a hardware store, but you will need to bend it over/behind the seal when you close the doors on B (mid or door)-Pillars or just let in hang/adhere over the paint on A-(front) & C-(rear) pillars. YES, it is a time-consuming process to tape off such seals and then remove the tape. BUT if you want to save your seals and pads, this is the ONLY way to go.

I say save your seals because many of them are infused/coated with a special UV-protection that keeps them from deteriorating & subsequent cracking from the constant sun exposure that happens over time. Cleaning these seals with a good All-Purpose Cleaner , like Meg`s Pro Detailer Line D101, and then applying a good rubber protectant, like Nextzett Gummi Pflege, should also be a part of anyone`s detailing process to enhance the appearance and prolong the life such seals. It is one of those over-looked items on a vehicle by many less-than-up-to-Autopian-standard detailers, both pro and hobbyists. Cotton swaps (AKA Q-Tips) work very well around window edge exterior seals or body panel seam seals, like roof gutters, for this purpose.

One problem with taping seals is that if this is done in hot weather or outside, which may be unavoidable for mobile detailers, is that the tape adhesive will stick to the seals when the tape is removed and this is a mess and difficult to clean off rubber seals. Some detailers will clean and then apply protectant to seals FIRST before taping them off. The obvious problem then is that the tape adhesive will not stick well then. It`s a debatable chicken-or-egg methodology which way to do it. I prefer to do mine after, but I detail in a garage out of the sun, so you may have to adjust your process to the ambient conditions at hand.

Edit: NEVER MIND with the above suggestion! I see that you are polishing the pillars with them REMOVED from the vehicle, so the rubber seals are NOT the problem. Are these pillars made of brushed stainless steel (IE, they have a straight-line grain or pattern in them) ??
IF you do figure out what is exactly happening, let us know!

My Captain Obvious question: How do YOU clean your pads of such Black residue?

[Desertnate]

The only thing I can add is it could as silver paint is abraded off the surface is shows up on the pads as black. Think about when you polish exhaust tips. They usually produce a black mess on the applicator as the polished metal or chrome comes off in minute amounts.

Agree on the level of aggressiveness of the products for the trim pieces. I never us more than a finishing polish and a medium finishing pad. Even then I run the polisher a bit slower and only make a couple passes. It doesn`t take much to clean them up whether it`s shiny plastic or the more satin finished paint. Depending on the vehicle, some of the painted areas are single stage despite the rest of the car being painted in clear/base coat.

[Rsurfer]

Depending on the vehicle, some of the painted areas are single stage despite the rest of the car being painted in clear/base coat.
In my experience, most B pillars that are smooth are covered with a film.

[Setec Astronomy]

In my experience, most B pillars that are smooth are covered with a film.

Yes, the ones with a more satin appearance seem to be "vinyl wrap". And then there are the shiny "piano black" some of which seem to be BC/CC.

[Desertnate]

In my experience, most B pillars that are smooth are covered with a film.


Yes, the ones with a more satin appearance seem to be "vinyl wrap". And then there are the shiny "piano black" some of which seem to be BC/CC.

On our `13 Highlander and `10 Honda Fit, they both appear to be painted metal. They are a satin, but don`t seem to react like I`d think something would if it were wrapped or some other form of film On the Honda, there are early signs of oxidation which looks very similar to single stage painted surfaces. I could be wrong though.

Some of the shiny piano black pieces may simply be a piece of plastic. On my MK6 GTI those shiny pieces could be popped off and replaced if they got too bad. They didn`t appear to be painted but seemed to be polished plastic with maybe some form of weather resistant substance applied to the external facing surfaces. My BMW, however seems to be as you described with a BC/CC paint as they are nothing like those on the VW.

[95maxrider]

Sorry for letting this thread die, I didn`t get any notifications and forgot about it!


95maxrider --

You said this --" when polishing certain types of plastic, usually the softer stuff (certain bumpers, door trim bump guards) my pads will turn black almost immediately, and no amount of polishing seems to stop it"..

We assumed you are working on a black single stage painted vehicle..

There will be no paint color transfer from healthy, clear coat, paintwork, unless you have gone through the clear coat, and are now hitting the paint under it..

The Griot`s Fast Correcting Cream is too abrasive to use on delicate painted areas like A B C pillars, and plastic parts like plastic bumpers, etc..

The Menzerna Intensive Polish is also too aggressive for those areas.. It is a cut of 5 and a gloss of 6..
Aggressive compounds will correct quickly and usually, not finish down really clear and glossy, like polishes do

I would use the Menzerna 3000 Final Finish, or the Griot`s Perfecting Cream only, for the ABC pillars.

In my experiences with these pillars, they are usually scratched by fingernails, which usually don`t do much deep damage, so a nice, mild, polish with a medium cut pad or less cut pad should suffice... You have to just get them good and then stop..

Whatever color paint that is on the pillars is not very thick and will go away quickly; and nothing short of a repaint will bring it back if you take too much off..
Dan F

This is all happening on a silver car with no black paint anywhere. So what happens if the clearcoat is somehow gone and I polish the silver paint. Will that show up as black on my pad, or will it show up as silver?

I wasn`t aware that I couldn`t use more aggressive polishes on painted plastic bumpers. Is that really true? As far as I was aware they got the same paint at the factory as the rest of the car. I`ve never read any warnings about that on any product I`ve ever used. Can you please provide some documentation about this?

Nowhere have I said that what I`m seeing is from polishing A/B/C pillars. That is not the case. I`m specifically referring to my painted plastic bumpers and door scuff guards, both of which have factory paint.

[95maxrider]

If you are getting "Black" residue on your pads from buffing black plastic A-B-C pillars, chances are you are also buffing the rubber seals around them and transferring that material to your pads.
To avoid this, you will need to tape off the seals with painters tape. 3-M Blue Pro Painters tape is good or CarPro`s Red Painter`s/detailers tape can be used.
The "problem" is that you will need to use a 1/4" wide tape and this size may be difficult to find these days. You may find this size at an auto paint supply store.
You can use 1/2" wide more commonly found at a hardware store, but you will need to bend it over/behind the seal when you close the doors on B (mid or door)-Pillars or just let in hang/adhere over the paint on A-(front) & C-(rear) pillars. YES, it is a time-consuming process to tape off such seals and then remove the tape. BUT if you want to save your seals and pads, this is the ONLY way to go.

I say save your seals because many of them are infused/coated with a special UV-protection that keeps them from deteriorating & subsequent cracking from the constant sun exposure that happens over time. Cleaning these seals with a good All-Purpose Cleaner , like Meg`s Pro Detailer Line D101, and then applying a good rubber protectant, like Nextzett Gummi Pflege, should also be a part of anyone`s detailing process to enhance the appearance and prolong the life such seals. It is one of those over-looked items on a vehicle by many less-than-up-to-Autopian-standard detailers, both pro and hobbyists. Cotton swaps (AKA Q-Tips) work very well around window edge exterior seals or body panel seam seals, like roof gutters, for this purpose.

One problem with taping seals is that if this is done in hot weather or outside, which may be unavoidable for mobile detailers, is that the tape adhesive will stick to the seals when the tape is removed and this is a mess and difficult to clean off rubber seals. Some detailers will clean and then apply protectant to seals FIRST before taping them off. The obvious problem then is that the tape adhesive will not stick well then. It`s a debatable chicken-or-egg methodology which way to do it. I prefer to do mine after, but I detail in a garage out of the sun, so you may have to adjust your process to the ambient conditions at hand.

Edit: NEVER MIND with the above suggestion! I see that you are polishing the pillars with them REMOVED from the vehicle, so the rubber seals are NOT the problem. Are these pillars made of brushed stainless steel (IE, they have a straight-line grain or pattern in them) ??
IF you do figure out what is exactly happening, let us know!

My Captain Obvious question: How do YOU clean your pads of such Black residue?

These are not pillars, they are the horizontal scuff bars that run along the doors to prevent dings. But I suppose the underlying plastic could be a similar material to some ABC pillars. These do have a plastic "chrome" strip that runs along them, that also continues onto my bumpers. Could this fake chrome be the cause of all this? Just to be clear, there is not a lick a real metal anywhere in these strips.

To clean my pads I hand wash with a lot of Dawn soap and it seems to do the trick.

[95maxrider]

The only thing I can add is it could as silver paint is abraded off the surface is shows up on the pads as black. Think about when you polish exhaust tips. They usually produce a black mess on the applicator as the polished metal or chrome comes off in minute amounts.

Agree on the level of aggressiveness of the products for the trim pieces. I never us more than a finishing polish and a medium finishing pad. Even then I run the polisher a bit slower and only make a couple passes. It doesn`t take much to clean them up whether it`s shiny plastic or the more satin finished paint. Depending on the vehicle, some of the painted areas are single stage despite the rest of the car being painted in clear/base coat.

Ok, that`s interesting, maybe that`s what`s happening?

The reason I used the more aggressive polish was because I pulled these off a car at the junkyard and they were pretty groady, so I wanted to shine them up to better match the finish of my car. I wonder if these were painted single stage, and I`m actually removing the silver paint. That`s probably the best explanation so far.