Some of these guys are just so hard headed....Just because he's been doing it 40 years doesn't mean he has been doing it correctly for 40 years. I have an cousin in-law that's around 70ish. Has a shop and turns out some really average to below average stuff. He had a heart attach and I was asked to finish a truck he was doing. This thing was full of acrylic spot putty, I mean tubes and tubes of it like using bondo. I fought and fought with the primer he had on there. I asked him what it was and he said "It don't matter, it's just primer and they all do the same thing". Finally got out of him it was Rustoleum from the local hardware store....I sprayed my first car in 1984 and I worked hard to stay with the quality materials, tools and trends. Anyway, sometimes you can't teach old dogs new tricks. I just smile and pass my advice along and move on. Let them do what they want. When I do it, it's my way or the highway. I've got to stand beind it. That truck in the upper part of this comment. It got stripped to bare metal and SPI epoxy and started over.