Author Topic: What finish for underside stoneguard - 67 SJ  (Read 1292 times)

Offline Fastback2013

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What finish for underside stoneguard - 67 SJ
« on: September 15, 2017, 03:58:43 PM »
Hello,

I have searched but could not find what the factory look would be for the underside of the stoneguard?
Would it be light grey with overspray of body color?
Or entirely body color?
In attachment a picture of my stoneguard, and looking at the positions where the fixation bolts sat it suggest body color?
Or red oxide (like backside of front valance) with body color overspray?
Thanks for clearing this out.
Have all a nice weekend,
Kind regards,
Jeroen
« Last Edit: May 09, 2020, 07:51:28 PM by J_Speegle »
San Jose 7R02C1708xx
Fastback GTA
built on 01/12/1967

Offline J_Speegle

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Re: What finish for underside stoneguard
« Reply #1 on: September 15, 2017, 04:06:23 PM »
Body color direct and overspray over red oxide. Different red oxide color/tint from your undercarriage or (for examples) fenders possibly.

The way the part is formed will guide you to how much and where direct spray and where more of an overspray surface will be.. Example for this part would be the face (forward) once the part is installed)


Since they would want to make sure this area was well covered with body color so as it was sprayed the area behind it would get direct or heavy overspray typically though the bent down or backwards edge would produce a shadow leaving mostly red oxide visible directly below and behind for a short distance, at the bend/form. So basically you can find nice coats of body color on the back side with thinner paint in the shadows to fine mist across the rear side with slightly stronger in areas directly behind focus sections. What you don't want is a nice coat of body color on exterior surfaces and a nice red oxide on the back side with no overspray - of a great noticeable difference between the two surfaces that catches the eye
« Last Edit: September 15, 2017, 04:20:39 PM by J_Speegle »
Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline Fastback2013

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Re: What finish for underside stoneguard
« Reply #2 on: September 15, 2017, 04:42:03 PM »
Thanks, Jeff!
Greatly appreciated!
The last part, I fully understand :
What you don't want is a nice coat of body color on exterior surfaces and a nice red oxide on the back side with no overspray - of a great noticeable difference between the two surfaces that catches the eye
Since the stoneguard is a long, small piece , would it be hanged vertically for painting?
or rather held horizontally?
I do not know enough about spray patterns, but it must make any difference, I assume ?
Thanks again for your time and effort!
Kind regards,
Jeroen
San Jose 7R02C1708xx
Fastback GTA
built on 01/12/1967

Offline J_Speegle

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Re: What finish for underside stoneguard
« Reply #3 on: September 15, 2017, 05:11:05 PM »
The last part, I fully understand :Since the stoneguard is a long, small piece , would it be hanged vertically for painting?
or rather held horizontally?

Don't know. Never seen a shadow from the hook nor a run that would indicate a direction it was hung. Believe it was hung since that would match what we find in pictures and reduces handling of prepaint and post paint parts plus keeps them organized



I do not know enough about spray patterns, but it must make any difference, I assume ?

We would also have to take in account of the painters height, right/left hand, orientation of the part to the spray line and other factors but that is why we look for something in a range rather than a specific pattern on every one.

Here is a picture of a 70 upper valance to show how shadows were produced on the back side from the forward lip on that part.  The non-painted section has rusted where the red oxide was while where there is no shadow some body color can bee found. The rear edge was a sharp edge and did not face the exterior so there was not great effort made to paint that edge and due to this no overspray/direct application can be seen like from the front formed edge

Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline Fastback2013

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Re: What finish for underside stoneguard
« Reply #4 on: September 15, 2017, 05:48:00 PM »
By all means, very interesting!!
Thanks Jeff!!
Totally agree that it is quite impossible (for the most of us  ;) = hobbyists that restoring there car), that we can duplicate a correct estimation of left/right handed painter or at which height the piece was held, etc...
But you're totally wright about your explanation.
Thanks for adding that picture, it gives us a good visual taught of what you explained!
The unpainted section has rusted where the red oxide was 
Since my stoneguard was heavily rusted (see my added picture at the beginning) at the underside, is it a correct assumption that the red oxide was less durable than the actual (body color) paint?
Or am I totally wrong?
Or said in a different way : is the red oxide not the same 'quality' in comparison to paint?
Do not want to mix different items, but just saw the question from 'cmfuser01' concerning the finish of the inner fenders.
The pictures that you posted are very similar with the finish of my fenders, and where the rust (now) is, was there once the red oxide?
Just added/asked this for better comprehension, that's all  :)
Again, many thanks for your helping answers!
Kind regards,
Jeroen
San Jose 7R02C1708xx
Fastback GTA
built on 01/12/1967

Offline Bob Gaines

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Re: What finish for underside stoneguard
« Reply #5 on: September 15, 2017, 08:03:01 PM »
Maybe someone can confirm or dispel but I was always under the impression that moisture can migrate somewhat through unprotected primer to the metal underneath. The paint on the other hand not so much. That also may explain why the rust is where the primer was opposed to the area with more paint overspray.
Bob Gaines,Shelby enthusiast, Shelby collector , Shelby concours judge SAAC,MCA,Mid America Shelby

Offline J_Speegle

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Re: What finish for underside stoneguard
« Reply #6 on: September 15, 2017, 08:06:37 PM »
Thanks for adding that picture, it gives us a good visual taught of what you explained!Since my stoneguard was heavily rusted (see my added picture at the beginning) at the underside, is it a correct assumption that the red oxide was less durable than the actual (body color) paint?
Or am I totally wrong?
Or said in a different way : is the red oxide not the same 'quality' in comparison to paint?

Believe that you have the evidence that the red oxide didn't hold up as well as the exterior paint over the factory primer. Remember that the red oxide that was applied to the floor of these cars for example

Yes all the bolt on parts that were assembled at other plants and shipped in were prepped and protected during shipping to the car assembly plants
Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline J_Speegle

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Re: What finish for underside stoneguard
« Reply #7 on: September 15, 2017, 08:36:57 PM »
Maybe someone can confirm or dispel but I was always under the impression that moisture can migrate somewhat through unprotected primer to the metal underneath. The paint on the other hand not so much. That also may explain why the rust is where the primer was opposed to the area with more paint overspray.

Believe it depends on the type of primer. Straight old time primer does not seal out moisture and was designed (just my understanding) to improve the bonding of the top coat and the base providing short term protection over bare steel in this example. Primer sealer provide an improved bonding ability and had a barrier of sorts between the base and top coat . There was a period of time when locals would paint their cars with colored primer sealers then buff them to a shine locally. Think in general primer was a cheaper product than primer sealers but not by allot   

Epoxy primer sealers of the period were the next step up and protected the surface metal, helped bonding of the base and top coat but was more expensive and had other restrictive properties

Just my understanding from what was explained to me and experience as well as examples seem to support this but sure there is a greater and much deeper explanation
Jeff Speegle

Anything worth doing is worth doing concours ;)

Offline Hipo giddyup

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Re: What finish for underside stoneguard
« Reply #8 on: September 15, 2017, 10:27:40 PM »
Not sure how much was changed in assembly line practices, but for 65' they look to have been sprayed horizontally.
1967 Springtime Yellow Coupe, 289 2v 3spd, Metuchen built, Nov. 17th 66'
1966 Sahara Beige Coupe, 289 2v 3spd, Dearborn built, July 21st 66'
1964 1/2 Pagoda Green Coupe, 260 2v 3spd, Dearborn built, June 30th 64'
1966 GT350 Fastback clone, 289 HiPo, 725cfm Holley, 4spd, SanJose built, Nov 25th 65'

Offline Fastback2013

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Re: What finish for underside stoneguard
« Reply #9 on: September 16, 2017, 05:27:44 AM »
Thank you all for the highly appreciated explanations and provided pictures!
As always, I have learned a lot  :)
Kind regards,
Jeroen
San Jose 7R02C1708xx
Fastback GTA
built on 01/12/1967

Offline J_Speegle

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Re: What finish for underside stoneguard
« Reply #10 on: September 16, 2017, 03:36:49 PM »
Not sure how much was changed in assembly line practices, but for 65' they look to have been sprayed horizontally.

Not sure either - different year and plant so no telling
Jeff Speegle

Anything worth doing is worth doing concours ;)