Removing solidified lumps of building debris from car

haze23

Long story short, there are several lumps of some sort of building aggregate dotted over my car (thanks neighbour, maybe pick better workmen next time -- but that's a different matter). Not huge, so, 'so what?' You may think.

Unfortunately some of these are on the glasswork, meaning I can't open the window or use the wiper. There's debris on paintwork and trim (painted) too, as well as accompanying scratches. The material is solid and gritty, so I'm after advice as to what may remove it without additional damage. So far I've simply tried water to soften and attempted to saturate with window cleaner with vinegar. Not much success.

Any tips that don't involve, say, sanding down, which is likely to go horribly wrong in the hands of the inexpert? Any chance concentrated standard car wash/products will be effective?

So annoying, seems like one of those minor things, that, atm is a huge pain to sort out. Thanks. 

Nobbie1967

If it’s some cement based aggregate, then nothing is going to soften it other than acid which will probably not do the paint much good. I suspect it will have to be removed mechanically with a plastic scraper to break the bond and then go over with a polishing compound. What age is the car? What condition was the paintwork in before? On well looked after paintwork it shouldn’t be able to adhere very well, but on an old car it will be much more difficult to remove.

You could use a weaker acid like vinager on the glass to see if it weakens the aggregate and then maybe try on an unobtrusive bit of paintwork.

haze23

Thanks for the comments, I was afraid that the answer would be this is likely to involve doing more damage then repairing, and that could be quite extensive. Not sure how that's going to work with the glass. In terms of condition, while I haven't been in a position to clean to the extent I'd like, it's a case of it being dirty rather than marked. So virtually no noticeable chips, scuffs etc. before this, so pretty annoyed.

Sadly, one of those 'last thing I needed right now' scenarios but I'll have to see about a professional assessment and go from there. Thanks again for the input.

born_again

On your windows, try a razor blade at a low angle to get under the stuff. Should get it off without scratching.

baser999

Out of interest, what’s the neighbour and/or builders said about the damage? No offer to help pay been forthcoming? 

ThorOdinson

I'd be looking to claim against the builder. Either ask them for their insurance details, or if you have legal cover on your insurance maybe talk to them.