75 BBC Stingray

I was wondering what people would suggest to keep the rust to a minimum over the next several weeks as I get the seams welded and add gussets.

I don't want to spray a light oil, as it would contaminate the weld area. I could prime the frame and mask all the areas I am going to weld, but that would be a mountain of work. How bad is it to leave the metal bare for 3 weeks? The garage is insulated and has a good vapor barrier. With the cooler weather, I would expect the air to remain relatively dry...

Also, how did people weld up their seams? Did you weld a small section on say the front of the frame, then switch to the back, then maybe to the middle of the frame. That way no one section gets too hot to warp?

Thanks in advance!

Fevre

Can you prime it then wire brush the area you are going to weld?

MILO

After a frame was dipped in acid, it came back with a coating which protected it for a few months. To get it off we just wash it off with soapy water and it was good to weld/paint. I don't remember want they used back then, should be easier enough to find.

PureSilver

I hung mine in an unheated garage in cool dry weather and didn't have much problem. I used POR-15 to cover it about two weeks later.

We did the sandblasting after welding, and only fully welded the seams between the chassis connections- nothing forward of the front (under-engine) crossmember, and nothing behind the differential mount. We did it in stages so we wouldn't warp the frame, though I really don't think that would be a concern.

I still need to weld a clutch cross-shaft mount but will grind the paint off when I do.

LemansBlue68

You could try spraying it with high zinc weld-through primer. Make sure the primer would be compatible with the paint you plan to apply. This way you get two birds with one stone: Anti-corrosion benefit while welding and the frame is prepped to paint in the areas that weren't welded.

Weld through primer might be a bit on the expensive side, though. At least the stuff in spray cans is.

NHvette

What do you plan to eventually coat it with ?
Actually, no matter what coating or paint, an acid etch will help.
Use Naval Jelly - or some other Phosphoric acid treatment.
It etches into the surface and converts a thin layer of the steel
(Iron) to iron-phosphate. This layer can protect the metal for
months. It will also wirebrush or sand off easily for clean welds.

The weld-through primer sounds OK - but it will contaminate
the weld. Also, coating with POR15 or similar products - you don't
want primer on the metal - you DO want a phosphoric etch, though.

You'll need the frame outside to wash it off after etching.

When welding the front area of the seams, I just paused between
sections of about 10 inches. This also allows the welder to
cool - staying within the duty cycle of the machine (usually
about 20% - of 10 minutes). Weld 2 minutes - cool for 8.

mandm1200

I was going to suggest something like the Metal Ready from the Por-15 product line. It will not only keep the frame nice but will etch it so it's ready for paint.

bobs77vet

i have used this technique for the past 17 yrs and have never been disappointed, however i have only used a rustoleum self galvanizing primer and then followed by rustoleum oil based paints, i have never used a high quality automotive finish over this and would not comment on how it would work. I even left some 16 ga sheet metal painted only with the self galvanizing primer out in the weather for a yr to see what it would look like and it was not rusty.

75 BBC Stingray

Thanks for all of the replies. I plan on using POR-15 products. I believe the primer is called Metal-ready or something like that.

I plan on getting all the welding done in the next 3-4 weeks, so hopefully the rust will stay to a minimum. I'll look into the phosphoric acid etch coatings in the meantime though.

As for the welding, it sounds like doing a short section of 4-8", then moving on to another area of the frame would be the best. Any more suggestions are of course appreciated.

bobs77vet

i don't know your welding experience or what you're welding with, but alot of us hopscotch around onthe frame to keep heat down in any particular area and allow us to do alot of welding at once, and then repeatedly go back to the areas.

75 BBC Stingray

I'm not actually doing the welding, but a college of mine who is experienced will be doing me a favor. The welding unit is a 220V arc welding unit with a MIG attachment...