There was a recent thread on the Windshield Repair Forum that serves as a good reminder to set the expectations for your customer and provide any disclaimer that you might have prior to restoring the headlights on their vehicle.
A technician wrote that he had restored a set of headlights on a customer’s vehicle and the results were perfect, but a week later his customer returned. The customer complained that the coating had come off after pressure washing the bugs off of his recently coated headlights.
Any headlight coating can be removed from the lens by pressure washing too close to the vehicle; even the factory coating and paint can be stripped from the vehicle. To prevent this from ever happening, Delta Kits recommends that the headlights never be pressure washed.
When using either the Delta Kits Infinity 4.1 coating or the Delta Kits Coat2Protect headlight restoration coating, we recommend waiting at least 24 hours to hand wash the vehicle, and one week before going through an automatic carwash.
The moral of the story is to never, ever pressure wash headlights! Protect your work by verbally giving this disclaimer to your customers before restoring their headlights. You may consider having the customer sign the invoice stating they will not pressure wash their headlights.