RO-90 to dull chrome parts?

[rubber_ducky]

Hi all,

I have some chrome on my car that I’d like to tone down the shine of. BMW have a “pearl chrome” (matte chrome) that they use in their interiors. I’d like to emulate this look on the chrome exterior parts. The parts are chrome plated plastic.

I’ve done this in the past by hand with a scotchbrite pad with ok results. I now own a (new-to-me) RO-90 and am wondering if there is a pad/abrasive combo that’ll get me the results I’m looking for. Thoughts?

The parts I’m looking to de-shine are like those in the pic

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[Sparktrician]

You might be better off to use a glass bead-blaster.  Be sure to not use a grit-blaster, though.  They're far more aggressive and can easily cut through the chrome.

 

[rubber_ducky]

I actually reached out to a local bead blaster and he turned me away due to the size of the job. Harbor Freight has an inexpensive media blaster, but it’s still more than I want to spend given it’ll likely be one time use.
I appreciate the suggestion nonetheless

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[Birdhunter]

Would BMW have the matte finish parts?

 

[rubber_ducky]

Would BMW have the matte finish parts?

They don’t. They do have gloss black in their accessories catalog but I’m not crazy about that look on dark colored cars like mine.

I’ve considered using a matte paint protection film over them or clear matte plasti-dip.

Truthfully, I don’t dislike the chrome that I’m very motivated to getting it done anytime soon. But I’m in the process for refinishing some Carbon fiber parts and they dulled up nicely but won’t stay that way. (Pic below) But that project made we wonder whether that RO-90 could play a roll in the chrome project.

I do have a spare set of bmw “kidneys” so I can freely experiment.

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[Cheese]

Be careful...chrome plating on plastic parts is very thin.

On a bumper, the steel is first plated with a layer of copper & nickel. Then the chrome is laid on to a thickness of .001” thick. The idea being that the steel surface of the bumper is now immune from corrosion, not because of the chrome plating, but rather because of the copper & nickel plating underneath. The chrome plating is decorative only.

In your situation, there is no need for the copper and nickel coatings so the chrome is plated directly upon the plastic substrate. Consequently it is what it is. I’d suggest using a random woven web material, Scotch Brite or Vlies and attacking the surface in a tender manner as there is nothing underneath the chrome plating other than plastic.

Once thru the plating, life devolves suddenly.

 

[FestitaMakool]

I agree with Cheese here, those layers of chrome on these plastic parts are very thin..
There are som alkalic cleaners who “accidentally” do chrome and aluminium dull and matte. But, getting it uniform is not easy (I have tried, once!)

Getting in between the ribs on the grilles even with a Dremel is very difficult. A hard flat polishing pad (Those who look like compact cotton) with abrasive polishing compound is maybe the closest. But again, getting the result uniform would be a challenge.

I know that for restoration of plastic, magnesium/alloy parts there’s a technique of using baking soda, as a more gentle and subtle way of sand blasting. You also have water based blasting with granulates. These methods are possibly closer to achieving the result you’re after. Wet sanding by hand to get a matte finish and then polish is also safer.

 

[Jim Metzger]

Perhaps just a matte spray? Krylon and Rust-O-leum both have it.

 

[rubber_ducky]

I agree with Cheese here, those layers of chrome on these plastic parts are very thin..
There are som alkalic cleaners who “accidentally” do chrome and aluminium dull and matte. But, getting it uniform is not easy (I have tried, once!)

Getting in between the ribs on the grilles even with a Dremel is very difficult. A hard flat polishing pad (Those who look like compact cotton) with abrasive polishing compound is maybe the closest. But again, getting the result uniform would be a challenge.

I know that for restoration of plastic, magnesium/alloy parts there’s a technique of using baking soda, as a more gentle and subtle way of sand blasting. You also have water based blasting with granulates. These methods are possibly closer to achieving the result you’re after. Wet sanding by hand to get a matte finish and then polish is also safer.

I was a bit lazy when I posted that pic having borrowed it from the internet. Thankfully I’m not looking to get in between the verticals slats and all. Just the chrome finished surrounds. The pic in this post shows it separated from the black bit that has the vertical vanes.

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[rubber_ducky]

Perhaps just a matte spray? Krylon and Rust-O-leum both have it.

I’ve considered this but have shied away mainly from concern of the finish chipping given that they’re in the front of the car, absorbing road debris. That said, the bumper doesn’t shed itself of all its paint. But I don’t feel like it’s easy to get that quality of finish from a rattle can. I could well be wrong though.
Anyway, this is why I was considering PPF or plasti-dip. Both of which are flexible to some extent

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[FestitaMakool]

Matte spray may work, but chrome isn’t exactly the best primer for any paint. You would have to source the right chemicals.
I didn’t remember if you could easily split the ribs from the outer “kidneys” from my last BMW, but you did  [big grin].

I’ll ask my old colleague and friend, he’s a real multi talent when it comes to boats, motors, cars, mc’s and painting all of those as well. He might even have done something similar as well, if not I’ll bet he knows someone who’s done it  [wink].
Sanding and later polishing wouldn’t chip (unless the chrome chips that is) at least. Ive seen a lot of clear coat peel and chipping, I agree, it looks very poor. These parts eats gravel and stone dust at every drive..

 

[rubber_ducky]

Matte spray may work, but chrome isn’t exactly the best primer for any paint. You would have to source the right chemicals.
I didn’t remember if you could easily split the ribs from the outer “kidneys” from my last BMW, but you did  [big grin].

I’ll ask my old colleague and friend, he’s a real multi talent when it comes to boats, motors, cars, mc’s and painting all of those as well. He might even have done something similar as well, if not I’ll bet he knows someone who’s done it  [wink].
Sanding and later polishing wouldn’t chip (unless the chrome chips that is) at least. Ive seen a lot of clear coat peel and chipping, I agree, it looks very poor. These parts eats gravel and stone dust at every drive..

That’d be much appreciated.

I’ve had this spare set of kidneys hanging around for so long I’d be willing to try anything. Plus, nowadays all of the kids driving these cars swap the chrome bits for black right after driving their cars off the lot. Something tells me I can source these things fairly cheap should something go awry with the two pair that I already have

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[FestitaMakool]

The advise: Sand to matte finish then prime with acid primer, then color and gloss as desired..
Then again: If you opt for the above you could go bananas with your sander(s) first [big grin]
Edit: Hand sanding would probably yield best results. Sanding sponges with very fine grit are available with shops who carry gear for automotive body work. FT probably also have some to look at.

 

[FestitaMakool]

And, if you end up painting: keep anything, whatever that might be that has been in contact with silicone at least one mile away..
Guess how I know.. [scared] [embarassed]

 

[rubber_ducky]

And, if you end up painting: keep anything, whatever that might be that has been in contact with silicone at least one mile away..
Guess how I know.. [scared] [embarassed]

Thanks for your help/advice here. I’ll give this a go this weekend and report back how it came out. Cheers!

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[FestitaMakool]

Good luck! Looking forward to hear how you and your kidneys did [big grin]

Since you’re into auto shine.. have a look on this:https://www.milwaukeetool.com/Products/Power-Tools/Metalworking/Sanders-and-Polishers/2438-22X

It works great for repair polishing, regular polishing and grinding/sanding.
It’s not a ROS - but with the lambs wool pad and Autosol it’s just great!
Edit: It accepts air tool accessories..  [wink]