Pete what plant are you describing? The process IMHO, as you listed, is not correct for all plants.
Jeff, The chronology was taken from Charles' comments at the Paint Sequence thread on the HiPo site:
http://www.hipomustang.com/hpmx/topic.asp?TOPIC_ID=8817Since it stood uncorrected, I assumed it served for all plants. But now that you mention it, it does conflict with the description of the Dearborn process that Bob Fria gives in his book
Mustang Genesis. On pg. 152 he describes the paint process beginning with the engine compartment's black paint, then the light gray body primer (which was
only used on the very, very early and pre-production cars. It was discontinued soon after initial use in favor of the red oxide, which matches your statement), lastly the exterior body color. There was no mention of when the interior paint was applied.
Mr. Fria explains that the gray primer sealer was changed to red oxide after a "number of early cars" were built. It was determined that the gray didn't provide for the proper adhesion with the lighter colors of the new formula acrylic enamel paints due to an ultra-violet sunlight interaction. It's my understanding that the "first" Mustangs were painted with M30J (Non acrylic) Enamel, and this is indicated by the black background on the door tag. After 12/28/64, Ford made the switch to M32J Acrylic Enamel, and changed the door tag to a gray background to signify the different paint (Marti's
Tagbook pg. 24). In 1966, the year I'm currently dealing with in my blog, the door tag once again returned to the black background, and it signified the Acrylic Enamel. I'm not sure however, when the color of the primer sealer was changed. Was it changed right at the beginning of the 1966 transition to acrylic enamel, or did it follow sometime after that when Ford began exposing the newly painted cars to the sunlight?
You mention a gray sealer primer - The primer sealer was the epoxy red oxide color, the gray was a simple primer used to fill minor defects/. Referred to by some as a primer surfacer.
Charles made no distinction between a primer sealer and primer surfacer, but he did say that the sealer primer was "usually gray" (which it was, I suppose, up until January of 1965 - since there would have been no reason for Ford to change it until the newer acrylic enamel became their finish choice). Of course, that was his comment on December of 2008, and his (and your) understanding could have changed to the present red oxide. This is another reason why I've decided to refresh this understanding on my blog, and verify things with y'all.
It sounds, from your comments, that the paint chronological process differed in respect to the plants it was performed at. Might you explain the differences?