What kind of finish is on the aluminum bumpers?

[priya]

As I haven't had anything much I can do myself on my SX/4 I decided to sand and polish my aluminum bumpers as they have a number of scrapes in them.  I sanded the scrapes initially with 60 grit and then worked up to 220 grit and I noticed the sanded metal looks quite a bit different than the unsanded metal:


That's the sanded on the left and unsanded on the right.  I thought the bumpers were just bare aluminum but judging by what I see they actually have some sort of coating on them.  Does anyone know what it is?  I really like the look of my bare aluminum bumpers but I'm wondering if getting that finish will require a new application of whatever this coating is plus I had hoped to avoid sanding the whole bumper to remove it as it seems the sand paper needs to be 120 grit or coarser to remove it.

[iAMCheap]

I don't know, but I'd like you to try some Mother's Aluminum polish or metal polish and let us know how it looks.
My bumpers seem streaky and need some help.

[WoodenBirdOfPrey]

I'm pretty sure they're clear coated like most aluminum wheels are.

[68AMXGOPAC]

I think your stuck sanding them and clearcoating them again. My opinion, but at this point in your build, and how great the car looks, the bumpers would look bad just half sanded.If it's clear coat wouldn't it strip off like paint easier ??with paint stripper of course. I use Metall polish on my bike restores on all chrome, nickel plated, and aluminum.

[priya]

I have a high speed angle sander that I bought a buffing pad for.  A paint polisher runs at aprox 3500 rpm and my sander at 7000.  I used a fine polishing compound on it and I thought that would burn through the finish pretty quickly but it didn't have any noticeable affect - seems awfully tough for a clear coat, but maybe that's what it is.  I don't think I have any paint stripper but I have some paint solvent that removed paint on the car so I'll give that a wipe on the bumper and see what happens.

I won't leave them half sanded, I just wasn't planning on all the labour to go over the entire bumper surface with 120 or 100 grit and then work my way up to 600 or 1000 and then polish.  I might skip doing the front bumper though, I'll see how much labour I put into the rear bumper. 

[milliard431]

I hope you get them looking good so I will know what to do when mine get back from the body shop.

[priya]

I'll keep you posted Milliard.

[rollguy]

I'm pretty sure they're clear coated like most aluminum wheels are.

I would agree.  I think that any kind of paint stripper that is good enough to remove the clear coat would etch the aluminum, and that would not be good. 

[priya]

I spoke to hubby about it and he thinks its a clear anodizing.  He says its very tough and yes the whole bumper will have to be sanded off with 80 or maybe 100 grit.

[mudkicker715]

I spoke to hubby about it and he thinks its a clear anodizing.  He says its very tough and yes the whole bumper will have to be sanded off with 80 or maybe 100 grit.

Agreed. Its too tough of a finish to be a paint.

[eagleman]

Thats a big 10/4 on the clear anodizing.I used to work for a company that produced all the aluminum bumpers for G.M. and they were all anodized in clear coat.Tough as nails and a real pain to remove.Really tough to do by hand.I just bought my second eagle and the bumpers need refinished so I'll be watching this thread closely. Thought about doing it by hand like I did my alloy wheels but that coating is a tough one to deal with.Anyway good luck with your project and keep us posted.I'm sure there is a easier way just don't know what it is! yet!!

[Budwisr]

Eagle bumpers are not aluminum, they are a type of stainless steel. You will need to cut and buff them like any stainless trim and then they can be clearcoated to maintain the shine.

[mudkicker715]

Eagle bumpers are not aluminum, they are a type of stainless steel. You will need to cut and buff them like any stainless trim and then they can be clearcoated to maintain the shine.

I beg to differ. They are aluminum.

[priya]

Hubby says the bumpers are too light to be stainless steel, I'm inclined to agree.

[mudkicker715]

Just thought of this......a bumper only weighs 8lbs. So definitely an alloy metal.