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:
(http://i276.photobucket.com/albums/kk14/priyalynn/DSCF1290.jpg)
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.
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.
I'm pretty sure they're clear coated like most aluminum wheels are.
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.
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.
I hope you get them looking good so I will know what to do when mine get back from the body shop.
I'll keep you posted Milliard.
Quote from: WoodenBirdOfPrey on November 22, 2011, 05:49:23 PM
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.
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.
Quote from: priya on November 22, 2011, 07:38:15 PM
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.
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!!
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.
Quote from: Budwisr on November 22, 2011, 09:17:09 PM
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.
Hubby says the bumpers are too light to be stainless steel, I'm inclined to agree.
Just thought of this......a bumper only weighs 8lbs. So definitely an alloy metal.
I just had my bumpers sand blasted and then powder coated. They were pretty cheap to have sand blasted, and not all that expensive to have powder coated. They turned out really nice.
Quote from: mudkicker715 on November 22, 2011, 09:48:16 PM
Just thought of this......a bumper only weighs 8lbs. So definitely an alloy metal.
Yep, its an alloy, stainless steel. If you grind on one, it'll throw sparks. Aluminum does not throw sparks.
Quote from: Budwisr on November 22, 2011, 10:44:59 PM
Yep, its an alloy, stainless steel. If you grind on one, it'll throw sparks. Aluminum does not throw sparks.
I'll try that tomorrow. I know it weighs the same as a much smaller piece of steel.
Quote from: Budwisr on November 22, 2011, 10:44:59 PM
Quote from: mudkicker715 on November 22, 2011, 09:48:16 PM
Just thought of this......a bumper only weighs 8lbs. So definitely an alloy metal.
Yep, its an alloy, stainless steel. If you grind on one, it'll throw sparks. Aluminum does not throw sparks.
I vote for aluminum. Try a magnet. The bumpers are not magnetic.
[/quote]
I vote for aluminum. Try a magnet. The bumpers are not magnetic.
[/quote]
Stainless is not magnetic. Good stainless anyway.
When I took my bumpers in to be powder coated, he told me they were aluminum.
And I agree, stainless steel is not magnetic either. I got a new refridgerator over the summer that is stainless, none of the fridge magnets will stick to it. No more refridgerator art!
304 stainless IS magnetic (and will rust), but 316 stainless is NOT magnetic. The Eagle ALUMINUM bumpers would oxidize (as stated earlier) if they did not have some kind of finish on them (anodize, clear coat, powder coat etc.).
Quote from: casper on November 23, 2011, 01:08:22 AM
if they were stainless bumpers, no anodizing. they are clear anodized. aluminum starts corroding the moment it gets oxegen to it. it turns dark gray REAL fast. i think its ZOOPS that has a nice aluminum sealer that you polish the aluminum with, and it seals and keeps it shiny. now that you got that anodize off, you got to strip the entire bumper, and put something else on it. if you take some "never dull" and just keep rubbing in one spot, it will just keep being dark gray on the neverdull pad. thats the constant oxidation. stainless steel will NOT oxidize. you can just polish it up, and its like chrome. no coating needed. even if its an aluminum alloy, it will still oxidoze in no time, and be dull. since you already got started on removing the anodized coating, finish it up, and look into the zoops aluminum polish. its the only thing i really know of that will polish/seal aluminum and keep it shiny. good luck.
o and the car looks OUT STANDING!!!!
Thanks for the advice and compliment Casper. I'll have a look for the Zoops.
I've seen some that are aluminum and others that are chromed steel. I don't think the aluminum ones I have are anodized, though. They look solid throughout.
Someone here TIG welded up the bolt holes on his, and it was definitely aluminum.
I would imagine it varied by year and trim.
Quote from: Budwisr on November 22, 2011, 10:44:59 PM
Yep, its an alloy, stainless steel. If you grind on one, it'll throw sparks. Aluminum does not throw sparks.
Well, I took the grinder to the bumper and no sparks. I've seen a lot of stainless steel in my time and quite a bit of raw aluminum and it sure looks like aluminum to me. That combined with the much lighter weight than steel and I'm certain the bumper is aluminum.
Quote from: BenM on November 23, 2011, 12:29:40 PM
I've seen some that are aluminum and others that are chromed steel. I don't think the aluminum ones I have are anodized, though. They look solid throughout.
If you look at the picture I posted you can see mine has a coating. I thought mine were solid throughout too before I started sanding. Paint solvent and paint stripper wouldn't touch it, I'm using 40 grit to get it off, its very tough so I'm certain that it is a clear anodizing.
Quote from: priya on November 23, 2011, 04:39:20 PM
Well, I took the grinder to the bumper and no sparks. I've seen a lot of stainless steel in my time and quite a bit of raw aluminum and it sure looks like aluminum to me. That combined with the much lighter weight than steel and I'm certain the bumper is aluminum.
Well I stand corrected. I originally thought that they were aluminum until a couple years ago when I took a couple mangled bumpers to a recycle place. I had a bunch of copper and I thought I would get a couple bucks for them so I took them along. At the yard they used some sort of acid test on them and claimed they were not aluminum but stainless. When I heard that, I fiqured they weren't worth much. Actually they paid more for them because they were "stainless". I assumed they knew what they were talking about. About a year ago, I buffed out the bumpers on my Father's Concord and they did not seem like they were anodized, yet they were somewhat shiny, so it made sense that they were not aluminum. I'm guessing they might be chrome? This weekend I'll check the bumpers on the Eagles I own. I have five ranging in the years from 81 to 87 so It should be a good indication. Sorry for the misinformation. BTW Easy-Off oven cleaner is supposed to remove the anodizing from aluminum.
Quote from: Budwisr on November 23, 2011, 09:10:07 PM
BTW Easy-Off oven cleaner is supposed to remove the anodizing from aluminum.
Cool, thanks for the suggestion, I'll give it a whirl. I was thinking I wasn't going to do the front bumper because its way too much work but if the Easy Off works better I might do the front as well.
I happened to wipe off my bumper with a cloth that had goof on it that I had used to wipe up after removal. OMG did it shine up nice. On my front gumoer I just have 2 spots on each side of center whee a license plate had rubbed and scratched through the clear coat. Also have a couple spots of "white rust" but I may just give it an honest cleaning. It has just 58,000 on it now so I am trying to do a sympathetic restoration. I gave up on the cheap paint job idea though as there were quite a few of those parking dings on both sides so the restoration shop tally is up to $2000. In the end it will be a collector grade Eagle with an honest restoration. I still would not ask $10,500 like that other guy. My old paint's shine was as nice as any I've seen but no comparison to a modern 2 stage. Yes I did say 2 stage. I had said I wanted to go with 1 stage like it originally had but was convinced otherwise. I was told that it would come across as a short cut and also would not last as long. He also was happy to grab another $400 from my pocket but others have given me the same advice so I think he was just being honest. Originally he asked me the usual question, How long are you keeping it? I just said that it really doesn't matter as money was not my motive. I kind of feel like i have a responsibility here as how many low milage 1980 2 door sedans do we really have. I mean this baby never had even 1 rust bubble on it which is why I thought they would just about paint it for free. NOT! I have learned that a proper paint job will set you back a bit. It is far better to get a small loan and buy the best condition car you can. I know you've all heard that before but if you really like your cars done right it is cheaper. In this case I still got the best 1980 2 door that I have seen and now it will be a 1 footer instead of a 20 footer. Those small issues never show up on camera.
Quote from: priya on November 23, 2011, 04:39:20 PM
Quote from: BenM on November 23, 2011, 12:29:40 PM
I've seen some that are aluminum and others that are chromed steel. I don't think the aluminum ones I have are anodized, though. They look solid throughout.
If you look at the picture I posted you can see mine has a coating. I thought mine were solid throughout too before I started sanding. Paint solvent and paint stripper wouldn't touch it, I'm using 40 grit to get it off, its very tough so I'm certain that it is a clear anodizing.
If I remember around Christmas I'll go check a rough looking one I have in storage. All the ones I have are really hazy on the front and the bolt holes are corroded. That's why I'm not sure if they are coated in any way, or they could have just been buffed one too many times.
Not only will bolts rub away a coating, but aluminum is sacrificial around iron. I reinforced mine with steel plates and used a gasket to isolate them.
But I still see a haze reminiscent of untreated aluminum, so I hesitate to be sure that they all got the coating. I don't want to damage the ones on my car.
It's still a very good metal for exposure without anodizing because the surface corrosion protects the metal much like copper.
Bens gots a very good point...Aluminum and steel are electrochemically dissimilar and when they are in contact with eachother it causes a galvanic reaction which is basically the movement of ions from one metal to the other, this process is further amplified when other elements such as salt and water are thrown in the mix...the result being corrosion and deterioration of the metals.
I tried Easy off on the bumper today as Budwisr suggested. The instructions he sent me said to leave it on 3 to 5 minutes or it will pit the aluminum:
http://www.raydobbins.com/polishing/
I put it on and left it 5 minutes and then rubbed with steel wool and it had no effect. I reapplied and waited 15 minutes and then I could see the part of the bumper that had already had the annodizing removed was turning black under the Easy off. I took the steel wool to it and roughly half the anodizing came off although the part of the bumper where it had previously been removed turned black. I pulled out my 40 grit sander and the black came off the bare aluminum fairly easily and the remainder of the anodizing sanded off with perhaps 1/3 to 1/2 the effort the untreated anodizing took to sand off. It was about 50 degrees F. in the garage so that probably accounted for some of the extra time it took for the Easy off to work. All in all I estimate I removed the anodizing treated with Easy off in about 1/4 to 1/5 the time of the untreated anodizing. Still pretty slow but no where near the hair pulling out/screaming experience it was without the Easy off, so two thumbs up, thanks again, Budwisr for the suggestion!
Thats interesting.I tried easy off on my front bumper today just to see what would happen and it seemed to work pretty well.I left it on around ten minutes and then used fine steel wool and the wool and bumper turned black.Used a clean rag and wiped it off and looks to be ready for some serious sanding.Not to bad I thought to myself so I tried it on the rear bumper and nothing and I mean nothing.Maybe I didn't leave it on long enough but will try it again tomorrow and leave it on longer.Was thinking after doing a small section on the front bumper that this ain't gonna be to bad.Now not sure but will try again.
Glad the tip helped Priya. I think warmer temps would have helped the process. One important point when using oven cleaner, it needs to be the "old fashion" type not the newer low odor type.
Also over the weekend I inspected my Eagles closer and all of them (5) have the aluminum bumpers. Maybe the chrome bumpers were pre '81. Also after talking to some other AMC guys, I believe the alloy used is a Zinc -Aluminum. The bumpers are very hard, most likely in order to meet the 5 mph crash requirements. I think that is why the recycle guys misidentified the metal as SS. I tried a brass key scratch test and the brass doesn't seem to touch the alloy.
Maybe thats why,I used what wife had in her laundry cabinet and it was the new low odor type.Will pick up the old fashion type tomorrow and give it a go.Thanks for the heads up.
just don't get it on your paint because it will take it off as well. my has used this stuff to strip a car thats how i know.
I used the regular Easy off rather than the low odour.
Quote from: eagleman on November 29, 2011, 08:25:43 PM
Thats interesting.I tried easy off on my front bumper today just to see what would happen and it seemed to work pretty well.I left it on around ten minutes and then used fine steel wool and the wool and bumper turned black.Used a clean rag and wiped it off and looks to be ready for some serious sanding.Not to bad I thought to myself so I tried it on the rear bumper and nothing and I mean nothing.
I had a similar experience today. I had initially used the Easy off on the side of the bumper and I hadn't touched the top of the bumper so today I sprayed the top of the bumper with Easy off, waited 15 minutes, didn't see any black, so waited another 5 and took the steel wool to it and it didn't remove any of the anodizing. I figured I'd try sanding the top of the bumper a bit and reapplying as the spot I did on the side of the bumper had had some sanding before I put the Easy off on it. I spent 5 or 10 minutes on the top of the bumper with 60 grit, just long enough to remove the shine, and then reapplied the easy off. After 20 minutes I took the steel wool to it and it removed perhaps 1/3 of the anodizing and thinned out the remainder of it a bit. I went back with the jitterbug and the 60 grit and once again its comming off a lot faster than with no easy off, but its still pretty slow going - about 45 minutes of sanding and there's maybe 15% of the anodizing left although the bumper has slight vallies in it so the flat jitterbug takes a long time to sand down the surrounding "hills" to get to the vallies. The anodizing is incredibly tough, the best approach might be to sand initially with 40 or 60 grit for 5 or 10 minutes, apply the easy off, clean, sand again for 5 or 10 minutes, apply easy off again and then sand again.
Well then I'll try that and see how it goes! Wife went into town today so I had her pick me up a can of the regular oven cleaned and about all it did was stink up the garage.Was rather disappointed but I should have known it wouldn't be that easy. So tomorrow its back to the drawning board and I'll sand it first and try again.There is no doubt in my mind that we'll get it sooner or later.
Quote from: eagleman on November 30, 2011, 07:52:54 PM
Well then I'll try that and see how it goes! Wife went into town today so I had her pick me up a can of the regular oven cleaned and about all it did was stink up the garage.Was rather disappointed but I should have known it wouldn't be that easy. So tomorrow its back to the drawning board and I'll sand it first and try again.There is no doubt in my mind that we'll get it sooner or later.
You might look into getting them sandblasted. I had a pair of bumpers done for $35.
I finally got finished sanding and polishing the rear bumper. It looks shinier in person than it does in the picture, but here's before:
(http://i276.photobucket.com/albums/kk14/priyalynn/DSCF1290.jpg)
And after:
(http://i276.photobucket.com/albums/kk14/priyalynn/DSCF1301.jpg)
Came out real nice, but I think it took me around 40 hours! I won't be doing the front bumper.
40 hours? Holy smokes, you have dedication! I would have walked away after the first 15 minutes and seeing how hard it was going to be. It looks great like everything you do though!
Thanks Woodenbirdofprey. I guess having done a lot of bodywork in the past gets you used to tedious slow work, but this was particularly drawn out. Once I ruined the anodizing though I figured I had to see it through so I did knowing it was going to be a long time.
I'm going to look for that tomorrow, Casper.
Don't mind the forty hours of hard work! Its the knowning what the forty hours of hard work is going to render that keeps me going. Nice work Priya!
Thanks Eagleman. The time I spent on it could have been cut down quite a bit if I had used the sand/easyoff/sand/easyoff method at the start or done as Vangremlin suggested and had the bumper sandblasted. Also slowing me down was I did most of the sanding with a jitterbug which doesn't cut real well even with coarse sandpaper. I have an inline sander which is what is best for the coarser sanding but it was working poorly, frequently stopping or running so slow that it was actually faster to sand by hand (which I also did).
I would like to paint my bumper black. It looks like someone did, but they didn't prep it right or didn't put on enough layers because it chipped really bad.
(https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/s720x720/308123_10101506152350504_9384144_85732209_765749304_n.jpg)
I was going to use Klean Strip paint stripper, let it etch slightly, then sand, prime and paint. Would that work ok?
I'm a little foggy on what I did with the aluminum I painted, but if I remember correctly there is a special primer for aluminum. Hopefully someone else will post that knows better than me.
Use an etch primer made for aluminum then paint over it.
I wish I could afford that shipping. If I were to have someone sandblast it, would I have to use a certain kind of media? I was going to sand it down by hand :-\. I bought Dupli-Color Self-Etching Primer. Says it works on Aluminum, Steel and Fiberglass. I also plan to use it on the spoiler.
Here is a good website for prepping and painting aluminum, steel, and plastics. I used his directions for painting the plastic fender flares on my wife's pathfinder and it still looked good a year later.
http://www.overclockers.com/how-to-paint-steel-aluminum-plastic-and-acrylic/ (http://www.overclockers.com/how-to-paint-steel-aluminum-plastic-and-acrylic/)