No problem. When you are done get some of the Sonax Polymer Netshield and put it on.
Sonax Polymer Net Shield - 210 ml
This stuff is AWESOME. Put one coat on after your polish/detail. Wait overnight and put another coat on the next morning (or about 12 hours after first coat). It goes on like a wet wax, but you have to remove it before it dries.
One coat works great but after 2 coats of this your friend won't have to worry about someone pouring anything else on his car. Any liquid beads up and runs off like magic.
I started using this 2 weeks ago. Last weekend my car was in the rain for most of the day, then driven in the rain at night. The next day the car looked 90% clean. Instead of dirt being along the entire bottom half as usually happens after rain driving (even after a fresh wax), the water had washed right off and most of the dirt went with it. All that was required was a quick light water rinse and the car looked 100% again.
Best of luck bringing that paint back from the dead and glad to hear it's been going well so far.