Every time I see someone on other forums want to use this stuff, I think about sending them to this thread. Then the selfish part of me doesn't want this place to attract too much rifraf, so I mind my own business and move on.
I started a frame off resto on my Olds W30 in 2006. First thing I did was get all that magical p15 junk. Spent about $250 for 2 quarts or p15, 1 quart of chassis black + all their prep products. Washed and scrubbed the frame, put on their magic etch cleaner. And it dried faster than I could rinse it off. Added more, and scrubbed it off. The metal never turned black. Oh well, it must have been doing it's job because I followed the instructions. Sprayed on the first coat. It looked great. For the second coat, I missed the respray window by about 2 hours. The second coat balled up like water repelling on a waxed surface. Called their tech support and they said to sand it flat, then apply their etch primer and spray again. $50 later for an aerosol can (with rush shipping) of etch primer, and I was back in business. Sprayed second coat. Then 2 coats of their chassis black, which scratched off with a fingernail. The car has been sitting in my garage nearly untouched for 9 years out of frustration of using poo15. At least it is not failing sitting in the garage. Some day, I will put the car on a rotisserie, blast it off and start over with SPI!
Balled up second coat:
Easily scratched chassis black:
Before the second coat, I sanded off the p15 over the vin number to get a picture. The rust was still there! But, oh, wait. It's ok, this is the be-all, end-all paint over rust, restoration frame paint! (insert sarcasm emoji)
Moving on, in 2007, I sprayed the bottom of the floor pan and firewall with 1 quart of DP and SS urethane. If I recall the price was also about $250. It turned out great, but expensive. In 2009, Crastech (from the Olds forum) pointed me toward SPI, and I have been following SPI and this forum ever since.
I have since moved on to a ground up build of a 57 Chevy pickup to use as a practice project to learn how to do this the RIGHT WAY! It will be 100% SPI start to finish. The frame was done with 3 coats of epoxy. Looks awesome, only used about $50 worth of epoxy, compared to the $300 I spent on p15 to paint the Olds frame. Lesson learned!