Help, how do I get concrete staining off my car's paintwork

[Gixer968CS]

Hi all, I'm after some help. My neighbour recently had a new shed base laid. The builders mixed the concrete next to my drive and shortly after it rained. That was about 3 weeks ago (maybe a month). Anyway, I have now just come to wash the cars and two have what I assume to be concrete staining on the upper surfaces. The cars were very dusty, but so are all the cars around here so I assumed it was just normal air borne grime, but when I washed mine the paint on both cars is "stained". Image water marks from very hard water that just won't come off. There are also a few tell tale small grey spots that are baked on. I don't know, but I'm assuming the concrete dust settled on the cars and was activated by the rain which has now stuck to my cars. Any ideas how I can get this off? One car (Polo) is solid black, the other (Z4) is mettalic black. I guess a machine polish would cure it, but is there anything I can do myself?

BTW, I know I need to confront the neighbour, but let's park that for now as I'm mainly concerned with rectifying the paint work.

[lornemalvo]

I remove pigeon poo from my car with tissue soaked in water and left for 5 or 10 minutes. That's unlikely to work. Assuming I was free or given bail after assaulting my neighbour (not really), I would try one of the cement dissolving products, perhaps diluted more than recommended to start with, on a small area. They tend to be acids that neutralise the alkali cement. I might try a cloth soaked in the mixture on an area and leave it for a while, removing it before it dries. It may have eaten into the paint or lacquer but might polish out. There is at least one YouTube video that deals with this but I think it's in the USA, so the product they uses may be different.
Before trying anything I would take many photos in case it comes to court. If it is likely to come to court in a case against your neighbour or the builder, try to get a sample of the substance for analysis. You would win, perhaps the cost of a total respray. We are all liable for our actions under a common law duty of care.

[s55shh]

Claybar if you are lucky

[motco]

My garage is partially under a concrete roof and this leaks a bit. Alkali stains from the concrete have stained my silver metallic finish and it's proving difficult to remove. Watching this with interest.

[Summit_Detailing]

Autosmart Congo.

Cheers,

Chris

[Gixer968CS]

have found something call Speedy Clean, concrete disolver:

http://acleaningproduct.co.uk/product/speedy-clean...

Does anyone have any experience of this?

[lornemalvo]

It gets good reviews on Amazon, if repeated applications are used (assuming the reviews are genuine)