Undercarriage Primer Color; 69 Convertible

[J_Speegle]

So if my Eminger & Marti report show a January 8 build date, is that when it was built at Dearborn or AO Smith?

Eminger/shipping invoices I have only show when the invoice was prepared not the real build date. Look to the Marti report for that

This would be red oxide underneath?

Can't be certain but if data that has been shared of cars built before and after Jan 8th were batch from firewall rearward and red oxide epoxy sealer from firewall forward

[TLea]

I think it's important to understand for those who don't know there was no primer called slop gray that was used initially. Slop gray came about as a result of mixing leftover body color and with a primer to use it up and extend the use. So at the beginning of the model year and then again we see in January sometime the vats were started with red primer and then through mixing the other colors in as an artist would know everything would turn towards black or in this case dark gray. Depending on when other colors were put in you can see some crazy wild undercarriage colors. I have seen purple and green

[427hunter]

I think it's important to understand for those who don't know there was no primer called slop gray that was used initially. Slop gray came about as a result of mixing leftover body color and with a primer to use it up and extend the use. So at the beginning of the model year and then again we see in January sometime the vats were started with red primer and then through mixing the other colors in as an artist would know everything would turn towards black or in this case dark gray. Depending on when other colors were put in you can see some crazy wild undercarriage colors. I have seen purple and green

100% correct, my gt500 slop gray was dark and had lots of metallic in it. Rust Oleum graphite wheel paint was almost an exact match. 

[Bob Gaines]

I think it's important to understand for those who don't know there was no primer called slop gray that was used initially. Slop gray came about as a result of mixing leftover body color and with a primer to use it up and extend the use. So at the beginning of the model year and then again we see in January sometime the vats were started with red primer and then through mixing the other colors in as an artist would know everything would turn towards black or in this case dark gray. Depending on when other colors were put in you can see some crazy wild undercarriage colors. I have seen purple and green

I have seen a in your face Maroon color as my wildest color seen. I am sure there are others but to be clear to others reading for direction they are in the small minority compared to the predominate gray as has been described .

[J_Speegle]

God point Tim. Can see where newbies might think we are describing a specific color name.


As an aside concerning the colors that can be referred to as slop or batch color as mentioned its typically a gray - medium to very very dark often with some metallic and either a green or bluish tint. When you start seeing some very "different" looking colors in 70 Dearborn Mustangs with the introduction and popularity of things like brighter and flashier (thing Grabber) colors

Then when you mix that with a contrasting body color over spray you get some very IMHO unpleasant combinations. Thing Grabber Orange with a light green under carriage. In other cases the color or tint of the undercarriage color is fairly close to the exterior color, leading some in the hobby's early yes to believe that their car had body color on the exterior and under 

[J_Speegle]

Not sure why we forgot to post this link. It might help as well as offer some examples

https://www.saacforum.com/index.php?topic=929.msg6979#msg6979

Also thought I would post some examples of the some of range of what the mixed colors produced. There are even odder examples but thought I would stay, at this time, with the more typical colors or tints found. Some of these are from cars O took, others from owners and shops and finally some are from samples of floors I cut out and save in bags so that I don't have to rely on pictures with varying lighting when I can get a sample








Of course have plenty more

And some of the examples of the range of what the red oxide color follows were. Notice in both the grays and the red oxide that these are not flat finishes originally though with exposure to the elements they can get that look on some samples. Take notice of the reflection in the one well preserved examples

[rcgt350]

When a car was travelling on the line, I understand that the primer was shot up towards the entire bottom, did it not keep applying that same primer right to the front crossmember? From what I've been reading it sounds like it stopped spraying in around the firewall area. If so was the next area up to the front crossmember hand sprayed?

[J_Speegle]

When a car was travelling on the line, I understand that the primer was shot up towards the entire bottom, did it not keep applying that same primer right to the front crossmember?

From what I've been reading it sounds like it stopped spraying in around the firewall area.

The car/unibody was traveling in the direction so that the front of the body entered first so the floor application started at approximately the bottom of the firewall

This produced allot of runs and drips in an effort to cover as much as possible. Vertical surfaces were sometimes thin or nothing more than a mist because of the angle. Also, the jets stopped spraying before they reached the very back of the rear. Just forward of the rear cross member. All of this was to eliminate the raining down of paint and overspray on the car being coated and the car following. Some times a single or multiple jets clogged producing a strip of unpainted floor for a foot or the whole length of the floor. Not common at all IME but did happen. Have seen examples (other plants and years) where it was recoated by hand or not caught by any of the inspectors 

If so was the next area up to the front crossmember hand sprayed?

After the rear 2/3rds of the floor area was painted the front frame sections and inner fender panels were coated by hand so that the spray could be controlled. If they had used the under-car spray system from the front cross member rearward all of the jets mounted in the middle and outer edges would have "thrown" their paint upward and not hitting any panels would have rained down everywhere creating a mess to fix and clean up

By applying the hand applied spray second it allowed the painters to cover over the earlier coating of the floor and reduce the chances of leaving a gap between the two applications which would rust quickly in most regions


As a mention the products used were not what most people thing of when they think "primer" so using the term is misleading. Primer is an open surface that promotes attachment of following coats and applications of other produces. They will allow rust to start. Instead a primer sealer was used at some plants that was epoxy based which produces a low to higher gloss finish. For this year and plant a epoxy primer sealer was applied or a base with left over paint from either the last shift or when ever the workers collected the near empty drums and poured the remains into the vats to create a combination that would be used during those production periods

The source that supplied paint/primer sealer to the floor jets was a different source than the one that supplied the hand applied application for the firewall forward.

[shelbymann1970]

May 6th 1969 Dearborn. clogged sprayer to boot.

[shelbymann1970]

April(can get the exact date) 1969 Dearborn Boss 9.