I sand blasted the visible rust and pitting and left the remainder of the paint on to strip by hand.

Well as good as I thought it was....it was not.

I have prepped it and treated it with phosphoric etch. Think it's okay to go with epoxy?

It is on the inside btw....


This is the blasted area.




Here is the pitting under the paint..

 

A little different than what I usually see. Looks like moisture got under the paint instead of rusting from inside out.
I would think you could stop the pitting by using a rust neutralizer.

 

I wouldn't worry about it too much if it's on the inside of the roof. You'll be putting a headliner in, right?

I'd primer or use a rust convertor and paint it, then put your isulation on and put the headliner in....

 

I had a lot worse pitting on the top side of my '37 Buick. It was pretty deep but there was no way I was going to blast that big a piece of sheet metal. I got a bottle of Krud Buster rust remover, a phosphoric acid based product, and a stainless steel brush and went at it. It got the pits completely cleaned out in a relatively short period of time.

 

That looks good Bob..

 

Thanks, that is a BIG roof panel. It probably sat out in the elements for decades. It had a thick coat of hardware store paint but it was really bad. I removed the dried out paint with one of those fiber wheels on an angle grinder and then went after it with the rust remover. I think it took maybe six hours to get all of the rust out of the pits, right down to clean steal. First lesson I learned though is not to rinse it with water, it will flash rush fairly quickly. The phosphoric will dry and leave a film which I sanded off just before I applied epoxy primer.

 

Wish I had known about that stuff years ago...I better write it down or I'm sure to forget...lol

 

We're there black spots left? Or you actually scrubbed it all out?

On another note, my gaps are looking good...

 

When I looked really close into the pits it was clean metal, no black spots. I worked on the entire roof, keeping it wet with the product and scrubbing with the stainless steel brush to get down inside the pitted areas. There are a lot of products with phosphoric acid for rust removal, I bought mine at a local store and I think it was cheaper than the other, I don't remember, but it worked great. Also, if you do research you'll see most product form a protective film to prevent rust and convert any remaining rust to another product. I don't exactly remember, just do the search, you'll see.

 

Hey Clinton, I guess you took off your roof panel to remove the drip rail? It looks like the panel itself is in good shape, and your fit is nice. I know my roof panel is swiss cheese. That will be a project for later. Bob, I like that Buick. A 4 door is neat! Is that one done?

 

Greg, unfortunately the Buick has been on the back burner for about three years. Business problems and other things have come about. I have the body work on the main body done and have it in primer.

I rebuilt the front cab corners, rocker panels, rear quarter panels and wheel wells and trunk floor. About 30% of the total body.

1937 Buick Special Page

 

That will make a great cruiser!

 

Yeah, if I ever get it done.

 

Aren't you suppose to neutralize the acid when done scrubbing so it doesn't continue to etch? I use Eastwood's version Fast Etch and their instructional video shows a wipe down with solvent for that reason. For small parts I rinse or dip in a solution of baking soda and water.

 

Phosphoric acid is different, no only is it non toxic it leaves behind a protective coating of phosphate that inhibits rust if you wash it off before it dries you actually wash off the protective coating. Auto manufactures use phosphate acid dips as one of the steps for corrosion protection prior to paint.
You are better off leaving the surface alone and just wiping down with thinners prior to paint.


It is the same stuff they use in hot tanks/acid dips for cleaning rust off stuff. The Krud Kutter metal clean and etch/ paint prep is just a stronger concentration of phosphoric acid. Phosphoric acid can also be found at concrete supply places like Brock White as concrete cleaner.