The Stovebolt Site Forums The Shop Area Paint and Body Shop painting patch panels prior to install

I am finally back north where I can work on my 53 truck. I'm mocking up the many many patch panels with sheet metal screws, hoping to check everything for fitment prior to welding, recommended by Carl52 I think. I'm wondering if I should paint the patch panels with something, epoxy or ? for future rust control, prior to welding them in place. I'm particularly thinking of panels that will no longer be accessable, i.e. insides of cab corners , and cowl panels, etc. Should they be painted first, or is the black coating on them from the suppliers adequate? I was thinking of painting them with epoxy and then sanding it off around the weld areas, prior to welding. Is this a good idea, or overkill?

Not sure how much good it does but I've used weld through primer on the inside of some patchs that would be nonaccessible after attachment.

I used a rust encapsulator POR-15 for these kind of areas. You will not be able to get all of it on the patch due to welding. I TIG welded all my panels which leaves a small heat affected zone but there still is one. How do you plan to use the truck? All weather, outdoor storage, etc. My truck is fair weather only so I don’t think rust issues will ever come into play in my lifetime.
https://www.flickr.com/photos/advance-design_parts_co/8129083489/in/album-72157631867396207/

Robert (MPandC) does use epoxy paint on patches, and uses a flat tip drill bit to remove the paint in plug welds.
It can't hurt to paint them, but when you think about it, will panels rust thru in your lifetime if left uncoated? Maybe if you drive the truck thru a vat of acid.
It's a personal preference, IMO. I have brushed on some epoxy in areas that will be concealed in my work, which is a lot less trouble than setting up to spray it. That's another trick I picked up from Robert.

I've used Encapsulator, weld through primer, epoxy primer, what ever fit the situation. On the Burb fender well, I reached up between the inner and outer panel with Encapsulator and sprayed as much as I could. With the A project, everything comes apart. So a lot of Epoxy, then clean where you need to weld. Hidden/folded stuff got weld through.

To what Keven said, look inside your A pillar when you can. Or even far up under the dash. No protection and 70 years later, a layer of surface rust with no rot through.

To add to what Mark said, here's a shot of the underside of the cowl on my cab where the blaster couldn't get to. A little surface rust, but still solid after nearly 70 years. Compared to the lower sections of cowl that were totally rusted away, it's not a big concern. But I plan on getting some kind of coating down on the bottom parts that will see road spray and possibly collected moisture.

Thanks guys, that kind of answers my question. I'll be using my truck for an around town daily driver. I don't drive any of my old vehicles in the rain unless I get caught out somewhere, and have to. I will never drive it in the snow. I keep both rust Encapsulator and epoxy around anyway, so I'll just use those wherever it makes sense.

Try this.

One thing about most of the areas where we replace spotwelds with TIG or MIG welding, if those areas do rust (and they will), it will never show as long as you keep the inside of the truck dry and the exterior prep and paint was done right.
Can one lessen the amount of metal affected by welding by using weld-thru primer? Yes. Can one eliminate this affect entirely? No.
Now you need to ask yourself this question. In the time which you have left in your lifetime and your kid's lifetime, will anyone ever know if it was used or not?