Factory rust coating - can anyone identify?

[EBGeek]

The short story is I recently picked up a '71 that I'm doing a mild teardown on and was in the process of cleaning underbody/frame in preparation for KBS coating. I noticed the underbody had a striking shortage of rust (as I've seen on my previous rigs) and noticed an orangish coating underneath while cleaning via stripping brush that is super difficult to remove. I've seen mention here before about a factory rust coating...could someone confirm that is what this is? The picture below is the underside of the bed...

I realize its no big deal either way, just a curious question I figured I'd throw to the pros on here...

 

[Scoop]

Looks like red oxide primer.

 

[Justafordguy]

I was wondering the same thing, mine has none of that.;D

 

[70_Steve]

I've seen mention here before about a factory rust coating...

I don't think mine came from the factory with a coating of rust. I think that developed shortly after delivery...

 

[EBGeek]

haha, VT_Don and 70_Steve. You guys are on a roll today...

Guess I'll just be thankful for whatever it is/was and keep on stripping. Hope to have a new underbody seal on it in due time...

 

[EBGeek]

oh and thanks for the reply, Scoop.

 

[Hozr]

The factory primer on my 68 was a salmon/orangish color and it was a BITCH to remove! Looks like you have some spots of surface rust where there were dings or wear through the paint.

 

[EBGeek]

Hozr - that sounds exactly like what I'm dealing with. do you think there's any harm in leaving some of the primer in place before coating with KBS and painting with a rust seal?

 

[Hozr]

I stripped it to bare metal. There were all sorts of runs in the primer from when they dipped it at the factory. Not sure I'd leave it or how well anything will bond to it and no telling what's under it!

 

[Rustytruck]

I've had good luck leaving the factory red oxide and epoxy priming over it. Now the factory color coat is another story. Sometimes it lifts and sometimes it don't. I try to wet sand the color off and leave the factory primer when it works out.