Bodyman Dave, I can sympathize with your need and desire to continue to employ the old and time-honored methods your customers expect, and the products that you are experienced with and confident about using.
However, I must comment that every single product that you employ in prepping a panel to prevent rust and promote paint adhesion, are in fact "chemical treatments" and are also dependent upon chemical reactions to adhere, to harden (dry) and to seal the surface against moisture and oxygen.
The point I strongly made in each of my previous posts was that POR-15 needs a rusty surface to be effective, thus if you found any paint or rust free metal under the POR you were removing, that is an indication that the product was improperly applied.
I am not so naive as to expect the established big-business refinishing industry or pro-shops to ever adopt such a simple solution, firstly, their business is built around extracting the maximum profit from every product line, from every sale, and from every service.
Further, and I am extremely aware of this, EPA restrictions limit O.E. suppliers and manufactures options with respect to the release of Volatile Organic Compounds (V.O.C.s) this is one of the reasons that G.M. is having to build a new body facility to replace the old Fisher Body Plant that is now located in a down-town Lansing neighborhood, and has been a continual source of citizen complaints about 'strange' odors.
Products like POR-15 will never meet the Air Quality requirements of high volume industrial usage, as the cost of meeting these standards would be prohibitively expensive.
The best and most durable protective coatings that chemistry can devise will never be made available to the general public (including commercial body shops) for well founded environmental reasons.
POR-15 is NOT a paint, but a coating based on the same basic chemistry as 'super glue', it does not dry, but hardens through a chemical reaction with the humidity in the air to form a tough protective barrier impermeable to water and oxygen.
Interesting that this product has been both praised and cursed at for years now, some of us swear by it, while others swear at it.
I am just a home hobbyist/ restorer with no vested business interest to protect; YES, IT WORKS FOR ME!
Jessie J.
I also feel a need to digress a little here and relate a little of my early years with Fisher Body Division, When I began working for them in 1968, the last step before applying primer was a final wipe-down of all exterior panels with 'Metal-Prep' this product was a dilute acid and would cause a thin orange film of iron oxide (rust) to form on the surface to promote primer adhesion.
A few years ago I had occasion to chemically strip the paint off my low mileage 1960 Impala, and every panel had that same orange 'patina', folks that strip their cars by mechanical means, such as blasting, or D.A ing usually are not aware that that original factory applied layer of rust is what had been holding their paint film in place for all those years.