Paintjob...what kind of original primer was used?

[montmorcey]

Im down to bare metal to 98%, but still working on getting all the spots off (and in some areas a little more than spots). What i have left is a brownish paint, probably some kind of original primer. Speaking to the guys at the local paintshop they say that if the paint comes off when rubbing with thinner, then i need to get it all off in order for the new paint not to rise. But ive used thinner, and rubbed until my hands bleed...but it takes forever to get the darn paint off. Do you think its necessary to get that old thing off completely?
Do you know if the original primer was brownish and thinner resistant (is it called 2phase paint?)?

 

[stock1970]

It was brownish red. and if it is stuck on then scuff it and reprime

 

[allenfahey]

I'm not sure what the factory used for the base metal back then but I suspect it isn't anything like the e-coat they use now. It is probably just sealer but is definitely tougher than the top coat. When I started painting in the early 90's we would still get an older early 80's vehicle with lacquer or enamel paint job in every once in a while. They would lift if you got the etching or primer with reducer in it on the feathered area of the paint. The reducer is what softens the substrate and cause it to lift. It would lift or ring up on the top layer, not so much on the first layer. Since there is no way to totally strip the whole panel when we repaired a repaired panel we would be careful not to over apply the etching or primer. We would apply the etching or the primer dry at first for a couple coats. Then apply it wetter after it flashed off. Another way to combat it was to not use any reducer in the epoxy for the first coat. It would have alot of orange peel but the reducer wouldn't lift the edges. We would then apply the reduced primer.

You state that you have 98% off and it isn't lifting now. I would just go ahead and prime it. I have a feeling you are going to be fine if all you have is the sealer coat from the factory.

 

[73azbronco]

Didn't they dip these things in vats of grey/reddish primer? I had a 65. Econ van with what looked like dried drips of grey paint, and a 66 bronco with the underside showing red primer with drips.

 

[broncobilly72]

If I remember correctly, the red tinted primer was zink based to help with rust issues. I think that you can paint just about any primer over it except laquer based primers without lifting the original red primer. Easiest way to test it is to place some paint thinner on a rag and rub the primer......fi it lifts then is is enamel based...laquer thinner or acetone should remove it if that's what you want.

Mike

 

[Rustytruck]

When painting my Bronco I removed all the top coat but left a fair amount of the factory red oxide primer. I then epoxy primed everything. I had no lifting, wrinkling or paint chipping issues in my primer or top coats. After Epoxy Priming I wet sanded to 360 and left no shiners of bare steel or previous factory primer or Bondo bleed through. If I sanded through I epoxy primed the spot and sanded again. I acid etch and soap and water washed everything Before laying down the epoxy primer. Since it took me months to prep the body for paint when I was finally done with all the body parts I did a final acid wash and soap and water bath and did a flash sealer coat of Epoxy primer just beffore laying down the color.

 

[Pa PITT]

I sold DuPont fro 30 years.. If the old primer is stuck don't worry no more.. Scuff it and get some 2K type primer.. basically some kind of Epoxy primer ... .. Beware of the window on your primer.
.. If you miss the window of time.. Your top coat can sure peel.

 

[allenfahey]

I sold DuPont fro 30 years.. If the old primer is stuck don't worry no more.. Scuff it and get some 2K type primer.. basically some kind of Epoxy primer ... .. Beware of the window on your primer.
.. If you miss the window of time.. Your top coat can sure peel.

I have to ask. What do mean by beware of the window of the primer otherwise the top coat can peel? Why would the topcoat peel? You have to sand primer so why would it peel?

 

[Quick & Dirty]

What do mean by beware of the window of the primer

There is a certain time window you have to apply a top coat without the need to sand it. If you are going to sand anyway, then you don't have to worry about it much, except to let it cure sufficiently before sanding.

 

[allenfahey]

There is a certain time window you have to apply a top coat without the need to sand it. If you are going to sand anyway, then you don't have to worry about it much, except to let it cure sufficiently before sanding.

OK, I think you and PAPITT are thinking of sealer, not primer. Sealer and primer sometimes the same product but mixed with different ratios or additional additives to covert it into a sealer. Primer is alot thicker and is what the OP should use once he feathers the remaining original coating. If he goes straight to sealer after feathering it, it will work but it won't be very pretty. He will see high/low spots where the remaining factory coating is. With sealer you do not sand. You wait till it flashes off, then you apply your paint. Yes there is a re-coat window with sealer but there is never any situation that would require you not to go straight to paint after it flashes off.

 

[Pa PITT]

Well it's been a long time since I sold my paint .. But we could write 75 pages on how to spray it correctly and I'm not sure we'd be done at that time..
The new primers .. sealers .. even paint to recoat have a window of time that you need to get your next coat onto it .. If it's too dry it'll peel off or flake off.
.. Been lots of years but I swear some of the 2part primers had a window of time to recoat them.
.. As far as sealers .. They can be sanded but, it sure best to not get to that point.
.....................
... Now granted I'm 10 years behind the new products but Once I was as good as I ever was .