Got lime stains on my alu trim

[mikeyew]

Hi guys,How do you remove the lime stains on aluminium trims on yourdoor. I work up today and found that my whole car was stained by whitish stuff, I think is lime, from water leakage from my toiletdirectly upstairs my car porch. The stains on the glass and body can be removed by normal washing but not the aluminium trims.It looked like it's been oxidized as I tried removing it using polish,vinegar, thinner, etc without any success.Have you ever encountered this before and how do you safely removethem without scratching the finish??

 

[kc's]

Do u have any polisher?
Eg
Metal polisher?

 

[mikeyew]

Do u have any polisher?
Eg
Metal polisher?

KC,

Yes, I've tried metal polisher(those in tube) without any sucess too.
I'm not sure it's oxidation or corrosion. If its the later
than its a goner. Can any one help me please???

 

[mikeyew]

Update: Today I tried using 1500 grid sand paper to
lightly sand down the affected area and follow with
Polishing using autosol metal polisher but sadly
the stains cannot be removed. It confirmed my
deepest fear that the bloody thing had corroded the
surface!!!! That just costs me 540 buckaroos, darn!

 

[terry8]

cheaper way - why dont you plastic dip it to the colour you want

 

[kc's]

Hi mike
Thanks for the update any pic to share

 

[rezzsya]

use coke and aluminium foils.settle.

 

[mikeyew]

use coke and aluminium foils.settle.

Bro, can you elaborate further how do you do that with
Coke and aluminium foil?

 

[johnwen]

i will wait for other people's sharing .

 

[kc's]

i will wait for other people's sharing .

u terral la

 

[mikeyew]

Some updates of what I found out...

Sad to inform that the trims are goner, can't salvage
em. It seemed that there is a layer of lacquer (matt)
on top of the aluminum metal to give it a semi gloss
finish. The problem with mine is that the alkaline
water from the leakage had eroded the lacquer and
edged onto the metal surface. Tried sanding them and
noticed that its shinny inside after the lacquer was
removed. Therefore, decided its nothing I could do
But to order a new part.

So please be careful not to park under anything that
may seem to have water seepage from concrete floor
Especially in multi-story car parks.

 

[antiquer]

Sorry to hear that.. but look at the bright side.. u have a new trims.. congratulations!!. Hehehe

 

[consoglieri]

It's very surprising what some drops of sewage water or water coming down from concrete slabs can do to ur car. Thanks for informing us bro.

 

[plutoII]

Mike, the trims on your Beemer are aluminium thats already clear-anodized (to form a hard, colourless transparent layer) to preserve the gloss/looks over a long period. Anodized aluminium cannot be polished as the surface is very hard. As time goes by, the anodized layer will develop microscopic pinholes and cracks naked to the eye. Look closely at many older Beemers or classic cars and you'll see loads of "fine scratches" on every inch of the trim. Many of these are actually cracks on the anodized layer.

During rain or washing, the water seeps into the cracks and pits, leaving behind minerals under the anodized layer. That's why on many older Beemers, the trims usually have these whitish fungus-like appearance. Some could be on top of the anodized layer and can be abrasively machined away, while the rest are under the anodized layer.

In your case, the water could have mized with "building lime" (highly caustic) commonly used during construction, and this could have damaged the anodized layer. Do not attempt to partially sand the layer cos you'll end up scratching it. Even 600grit sandpaper has no effect on BMW's anodized layer.

Either replace the trims or remove the anodized layer via soaking with paint stripper/clogged drain chemical. Once stripped, the bare, dull aluminium can be repolished to any degree of gloss you desire. I hv spent 1 hour on 1pc of trim to polish it to almost chrome-like appearance! But since its bare aluminium now, it'll oxidize soon and require periodical polishing with metal polish.

 

[mikeyew]

Bro PlutoII, you're absolutely spot on.
However I also noticed that BMW had also coated
the anodized aluminum trim with a layer of lacquer
to protect it from oxidation. Unfortunately, in my case
the lime had already desolved that layer and had edged
onto the anodized aluminium. There are no other choice
but to get it replaced. :-(

- - - Updated - - -

Bro PlutoII, you're absolutely spot on.
However I also noticed that BMW had also coated
the anodized aluminum trim with a layer of lacquer
to protect it from oxidation. Unfortunately, in my case
the lime had already desolved that layer and had edged
onto the anodized aluminium. There are no other choice
but to get it replaced. :-(

 

[plutoII]

Bro PlutoII, you're absolutely spot on.
However I also noticed that BMW had also coated
the anodized aluminum trim with a layer of lacquer
to protect it from oxidation. Unfortunately, in my case
the lime had already desolved that layer and had edged
onto the anodized aluminium. There are no other choice
but to get it replaced. :-(

- - - Updated - - -

Take a look at an old 5series' anodized aluminium trim that was restored. Anodized layer removed, folllowed by loys of work.
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