What is the best way to remove black permanent marker from the bonnet of a white car?
The best cleaning method for this is dependant on what the substrate is. You want to remove the marker but not the paint below. Have a look at the marker pen that was used and see if you can determine the solvent that was used in the marker. Usually it is an alcohol or an aldehyde. If you can determine which solvent was used in the marker then that is likely your best solvent to attempt a dissolution removal. Try the solvent on the car in an unseen area first to see if it will mark the paint. If that doesn’t work, you can try some commercial rubbing compounds to abrade the mark off. Failing that, you can always paint over it with a touch up kit from the auto manufacturer, or ignore it.
