I have a job coming up this weekend from a client who's car has had water dripping on it in his garage. He doesn't know what dripped on it but he said it was white in color so I assume it's a mineral of some kind. Probably calcium or something.

So this will be my first time dealing with this sort of thing. I have 2 products in mind to deal with that but I am curious to know if someone ever had a case like this and what recommendations you could give me.

How would you approach this and what steps would you take?