Sanding aluminum trim: Wet or Dry?

Either.

Sanding wet lubricates the surface for a smoother cut and helps to keep your sanding paper from clogging up so you'll get more working time out of it. Also if you decide to wet-sand the add drop or two of soap to you water.

I've sanded slotted mags and then polished them out this way before because the surface was so deteriorated and rough.

It was tons of work and now days there's a number of different metal polishing pads on the market to do the job faster and better by machine.

What are you working on?

Make sure it's not anodized.


:)
 
hi Mike,

I haven't been able to find out for sure whether the trim is anodized or not, but it's too late anyway--the deed is done. I'd say the 800 grit sanding plus Mothers Mag&Aluminum Polish removed 50% of the oxidation. My process was: 1) clay bar; 2) sanding; 3) clay bar; 4) apply polish with terrycloth; 5) buff with MF.

The question is, how long will it last before it becomes re-oxidized. Anyway, what was the danger you were concerned about with sanding/polishing if it is anodized?
 
I would recommend wet sanding with a drop of dish washing liquid in the water simply because it will be easier on you and deliver a good end result.

If you sand any anodized surface you will destroy the anodizing. Anodizing only accounts for between .001" and .0015" of the surface. If the item is hard anodized that number can be as high as .003", but even then you will easily sand through. By the way, if someone tells you that a particular piece of aluminum is hard anodized and it's any color other than black or dark (dark) green, they are incorrect. Hard anodizing created pores in the substrate (aluminum) that is too small to accept colors (dyes).

Once you have polished the surface and gotten the shine that you want, finish it up with a good wax. DP wheel glaze is very good as would be any good hard Carnauba. I wouldn't use a soft wax or a liquid wax on a wheel, although some might disagree. I feel that a hard paste wax is the best protection for wheels.
 
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Jim Harvey said:
I would recommend wet sasnding with a drop of dishwashing liquid in the water simply because it will be easier on you and deliver a good end result.

If you sand any anodized surface you will destroy the anodizing. Anodizing only accounts for between .001" and .0015" of the surface. If the item is hard anodized that number can be as high as .003", but even then you will easily sand through. By the way, if someone tells you that a particular piece of aluminum is hard anodized and it's any color other than black or dark (dark) green, they are incorrect. Hard anodizing created pores in the substrate (aluminum) that is too small to accept colors (dyes).

Once you have polished the surface and gotten the shine that you want, finish it up with a good wax. DP wheel glaze is very good as would be any good hard Carnauba. I wouldn't use a soft wax or a liquid wax on a wheel, although some might disagree. I feel that a hard paste wax is the best protection for wheels.
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Come to think of it there's no way my trim could be anodized because Bavarian Auto sells a de-oxidizer product to BMW owners that includes sandpaper. I did dry sanding today and it came out OK, as I told Mike. It brought the oxidized appearance down probably 60%, from moderate to mild--but didn't touch the scratches. Tomorrow will be a nice day also, so I'll try it again with wet sanding and finish with DP Wheel Glaze.
 
EDIT: I checked the trim the next day in better light and I'd say the oxidation has improved by 80% at least. Quite a nice result for <$10.
 
stevehecht said:
EDIT: I checked the trim the next day in better light and I'd say the oxidation has improved by 80% at least. Quite a nice result for <$10.
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Good to hear, before and after pictures?

As for the anodizing, Jim Harvey is correct in that you can sand enough aluminum off that you can get past the anodized portions but it would tend to be a lot more hard work and getting into any kind of tight curves and such would require a lot more work. It would also seem as though it would bee too easy to sand too much on edges and not using really low grits for these areas.

I wouldn't try sanding anodized parts if the goal was to make the parts look polished and beautiful as an end-result. Too much work.

I've had parts de-anodized before but the de-anodizing process seem to eat away a little material in the process. Technology may be better today than it was about 15 years ago when I wad doing this kind of work but I don't know as I don't stay up on anodizing technology except to marvel at how far it's come over the years to the pretty colors available etc.


:)
 
We've been anodizing for about 15 years so we have a little experience in the field. <G>

Anodizing GROWS a layer on the surface of the piece. This is why some parts need to be made slightly undersized when the must be finish anodized (if they are a critical fit piece). threads are particularly troublesome and should not be anodized at all. Methods to prevent the thread from being affected by the anodizing process include capping, taping and plugging.

The reason that the de-anodizing process loses material is that you are actually removing the anodic coating that has been grown on the surface of the part. In this case, you will lose anywhere between 1 and 5 thousandths from the part surface depending on how long you need to "cook" the part.

There is no way to polish an anodized part after anodizing. If you want shiny AND anodized, then you polish BEFOREHAND and then proceed with the anodizing process. Anodized surfaces can be coated with a good quality wax which will afford additional protection to the surface.

Standard polishing of aluminum is done with a tumbler, buffer or by hand. There is also chemical brite dipping that uses some extremely powerful chemicals to achieve an exceptional finish prior to anodizing.

The only things that have changed in the last decade are the dyes (High UV resistance), masking materials and ability to multi-color parts. The actual process remains the same. Acid and electricity and time. the creative part has blown up in the last 5 years and there are people doing amazing work in the field.
 
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Jim Harvey said:
We've been anodizing for about 15 years so we have a little experience in the field. <G>
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Cool. Great to have access to an anodizing expert in the house.

Some window trim components on new cars are anodized black, (my best guess), and they fade over time and then members will post threads asking what can be done to make them dark black again and historically they don't like the answer.

My experience has mostly been with V-drive Drag Boat hardware and a few specialty decorative items. I know just enough to be dangerous.

:D
 
Mike.Phillips@Autogeek said:
Some window trim components on new cars are anodized black, (my best guess), and they fade over time and then members will post threads asking what can be done to make them dark black again and historically they don't like the answer.

:D
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They're not going to like my answer either.

Unfortunately, when you have an anodized part that has faded from UV exposure or become mottled from a combination of UV and exposure to the elements, there isn't really anything that can be done to restore the original color. The problem is that the color has actually faded from the pores of the aluminum or the coating has failed.

Modern Dyes used in anodizing are strongly UV resistant, but the key word is 'resistant'. Kind of like a watch, you never hear watched being called "waterproof" simply because at some point even the best watch will leak. If trim has deteriorated to the point that it has lost color or is mottled, the only solution is really to replace it, powder coat it or paint it.

Moral of the story is that as soon as you get your car, protect it. AG sells enough protectant products that you shouldn't have any excuse for not finding SOMETHING that will work for you. This is also a good point to make to your customers when you're detailing their cars. It's a lot cheaper in the long run to use a good quality wax or sealant with High UV factors than to go to the dealer to replace trim.

These forums are a great resource for everyone to get the knowledge they need to keep improving their skills.
 
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Thanks for all this, I felt like a sponge reading this.

You guys can continue enlightening me about this, I'm all ears willing to learn.
 
Thinking about Steve's original post, I would guess that his trim is uncoated aluminum. Probably highly polished in its original form. That will resist oxidation for quite a long time, but eventually, the oxides will overcome the polished surface and he'll start to see the chalking that is the signature of oxidized aluminum. The tip off for me was his statement that a kit was offered that contained sandpaper. You would never offer that to any kind of coated trim piece. So a fine grit to knock off the surface oxides and then a good buffing with the proper polish restores his original shine. Once you achieve the surface finish that you want, a good coat of wax will go a long way to keep that piece shining.
 
Wow! This is awesome information. I'm sure a ton of us need to know these things, so I'll remember you Jim and ask questions when I have them about trim.
 
Jim,

In your experience, can you chrome plate a piece of anodized aluminum trim, without removing the anodizing? Asking about a grill off of a 59 Chevy Impala. My brother is going to see about having this done.
 
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