Panel Prep for new floor pans

[Casting Timmy]

I am working on replacing my floor pans and the napoleon hat on my pan. I am grinding/sanding through to get the hat off as it's leaving me a solid portion underneath.

The flat parts for the hat to weld too have surface rust and pitting as over the years water got it there. I will wire brush it will, but was thinking about using Eastwood's Post weld treatment as it's a mild phosphoric acid solution then using their weldable primer so under the welds it has some protection.

Is this a good approach? I know some phosphoric acid solutions discolor, but I don't know if that will weld. This Eastwood stuff seems to not discolor and leaves the metal looking pretty clean.

Thanks for any help you can offer.
Tim

[67ctbug]

Try not to replace the whole hat... the aftermarket piece needs major work to fit right. I think you should use copper weld through, I hear it is better than regular weld through primer. Why not just use phosphoric acid too clean it up? It's easily available from Home Depot/ Lowes. https://www.homedepot.com/p/Miracle-Sealants-32-oz...YgodgBsKRA
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'67 Beetle L41
'74 Westfalia
'69 Plymouth "Adam-12"
'63 Ragtop
'73 914
'72 Dodge Wrecker
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World Series Champions 2016

[c21darrel]

^^^Interesting find at home depot. This is the one i always buy.
https://www.homedepot.com/p/Klean-Strip-1-gal-Phos...7Brest%7D+

I would sand blast the area, do my welding then grind, prep and paint. Eastwood has an internal frame coating if you are concerned with inside tunnel.
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[Casting Timmy]

THanks, I'll get some of that stuff from Home Depot instead of Eastwood. Probably get some interior tunnel coat later when I get it back together.

[theKbStockpiler]

I have read where weld-able primer has a lot of zinc in it and that some people just use spay cold compound zinc from Rustoleum as a substitute. I have never tested it so I don't have a personal opinion on it.
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My beetle is not competing with your beetle. I have the yellow beetle in my town. There is a red one, a green one ......
Use all safety devices including a mask.

[57BLITZ]

I feel it's best to do it the way VW did it . . .
Weld clean, bare steel . . . then paint it!
I have never considered using "weld-through" primer after reading of folks ending up with contaminated welds . . . I would rather have to replace the pans again in thirty years than have them come loose next year!

After I finished welding, I applied some thinned paint directly INTO the joints using a "hypodermic applicator" . . . capillary action pulls the paint right in like magic! https://www.gauntindustries.com/5-oz-products/?sort=featured&page=3
Sprayed the entire chassis, then applied seam sealer to joints after paint cured . . .

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Jesucristo es mi Señor y Salvador!

[theKbStockpiler]

You don't acctually weld through Weld-Thu Primer. It's best used in areas you can't paint after the panel or patch is welded in.
_________________
My beetle is not competing with your beetle. I have the yellow beetle in my town. There is a red one, a green one ......
Use all safety devices including a mask.