[kcyang]

Dear Sifus,

I have this stain from while idle for about 1 mth in parking lot.

It's a hardened substance resulting from concrete ceiling leak.

I tried using non-abrasive polish but it doesn't work.

Any suggestion?

Thanks a lot

Attached Thumbnails

• 

[CoffeeDude]

I would first try a clay bar.
If it doesn't work try a compound like M101.
If still don't work, try wet sanding.

If still don't work, change car

[vr2turbo]

I would first try a clay bar.
If it doesn't work try a compound like M101.
If still don't work, try wet sanding.

If still don't work, change car

Yup, try something more aggressive, but start from the least aggressive and move upwards to most aggressive products

[jonlsl]

Yup, try something more aggressive, but start from the least aggressive and move upwards to most aggressive products

You might want to try something acidic based since its those concrete water scale marks. Can try Forma hero rain spot remover for glass. Its an acid based product. Makes sure car is wet and cloth is wet. Used with caution and rinse well. Use in a small spot first.

Not sure if it'll work but can try lah. If it doesn't work then have to use abrasive method as mentioned above worse case respay area.

[vr2turbo]

You might want to try something acidic based since its those concrete water scale marks. Can try Forma hero rain spot remover for glass. Its an acid based product. Makes sure car is wet and cloth is wet. Used with caution and rinse well. Use in a small spot first.

Not sure if it'll work but can try lah. If it doesn't work then have to use abrasive method as mentioned above worse case respay area.

If not mistaken, remember those acid base glass cleaner did mention not to get them on paint, right?

[kcyang]

Thanks Sifus for the recommendations.

Will try out one after another. Probably will also try out those abrasive polish.

The stain was thick that i needed a sand paper to reduce the thickness.

Regards
Yang

[kcyang]

I would first try a clay bar.
If it doesn't work try a compound like M101.
If still don't work, try wet sanding.

If still don't work, change car

LOL, i like your statement "If still don't work, change car "

[CoffeeDude]

LOL, i like your statement "If still don't work, change car "

Many new car models launched in 2013

[S40]

Thanks Sifus for the recommendations.

Will try out one after another. Probably will also try out those abrasive polish.

The stain was thick that i needed a sand paper to reduce the thickness.

Regards
Yang

try AG SRP. It's close to a pure polish. However, if it's harden, then wet sanding would be the next choice.

[jklow123]

Dear Sifus,

I have this stain from while idle for about 1 mth in parking lot.

It's a hardened substance resulting from concrete ceiling leak.

I tried using non-abrasive polish but it doesn't work.

Any suggestion?

Thanks a lot

Im pretty certain the top surface of clearcoat (if its clearcoated) has been damaged by the stuff
from ceiling. It's probably not a dirty stain.

During construction, caustic lime (white powder) is often mixed with water, resulting in a boiling, highly caustic solution.
When theres any leakage within ceiling, that stuff gets moist and is "reactivated". Highly caustic.
Always look up at basement ceiling...if u see white goo dripping down, park elsewhere.

If i were u, id do 1500g sanding. If that doesnt solve it, you'd hv to respray the bonnet.