Well, I have finally had the opportunity to use the much vaunted POR 15 to rustproof David's 6.9. Obviously, I am in no position to laud its praises regarding the product's effectiveness as a rust preventative as only time will be able to reveal that, but I can certainly talk about how to use it, as some members that came to our get together and the Show and Shine day will testify.
First things first. There was probably as much of the stuff on my hands and face as in and on the car itself... and brother, let me assure you, once it's on your skin, you won't remove it in a hurry. No amount of solvents or thinners will touch it - you can also forget soap, detergents and scrubbing brushes - it will be there for days and not budge. So, the first precautionary measure to implement when using the product is to use very good quality, thin rubber gloves such as used in hospitals - not the everyday throw away variety that you buy at the supermarkets. Naturally, I was glove-free, wasn't I, happily ignoring instructions contained in the pamphlet that comes with the product.
Secondly, POR 15 itself is quite fluidity, and can be applied with a primer gun, especially if it is mixed with no more than 15% special solvent to thin it down - but, 15% max., no more. However, one would only use a spray gun if POR 15 was to be used as a top coat. My understanding is that one can even apply automotive paint over it after it has dried thoroughly - a period of some three to five hours depending on ambient temperature.
With David's car, I used an engine degreasing gun after removing all door trims, plastic entry steps and removal of the rubber bungs that allow access to the sill panels . I also removed said rubber bungs from the inside of the rear guards which are double skinned and suspect to rust starting internally. With the rear of the car up in the air and wheels removed, I also gained access to the rear chassis members.
Extreme care must be taken when using an engine degreasing gun because of the continuous drip from the nozzle - get that stuff on any cloth material, such as carpets etc. and you have to be QUICK to remove it - once it would set, forget it. I would also suggest that any drain holes in door panels. sills etc. be taped up prior to applying the stuff because if you don't, a lot of it will simply finish up on the floor or ground. Hope this helps with any 'budding' user of POR 15. Regards, Styria