Cement on cars

Does anyone know what will take cement dust off of a car without harming the finish?

I have a customer whose employee lot sits right next to a cement plant. Every so often the plant puts off a huge cloud of cement dust that coats everything. They have been giving tickets to the local car wash, I think they use a vinegar solution. I’d like to apply something to a bunch of cars at once then rinse. They don’t want a complete car wash, just removal of the cement dust. They said it can be pretty bad when it drizzles a little then the sun bakes it on.

I wonder if either citric acid or oxalic acid would do the trick. I’ve gotten a blend of phosphuric and sulfuric acid on paint without damaging it but I didnt let it sit, I think that you would have to do one car at a time and work quick. Wet the glass first, apply, then remove.

I’m not endorsing this, even though I think it would work

You need to bit of search work cleaning cement dust particles. We can only suggest vinegar but I think it is insufficient in your case.

Super Crete Relief Concrete Remover - 5 Gallon Pail