Weld-through or weldable primer

[got2haul]

I was thinking that when it's time to replace some small areas of the body panels on my '80 short wide, it might be a good idea to coat the inner side of the panels with weld-through primer prior to stitching it together.  I haven't used this stuff in the past.  Those that have, please share your comments and experiences with using the weldable primers.  Thanks.

[HAULIN IT]

Yes, It's a good idea. There are many companies that make it. I like the SEM brand, should be available at any body supply store in either a brush-in-cap can or a spray can. What I've found to work best is to coat all of the bare metal, but leave a 1/4" from the edge where your going to weld if your doing a seam (it's going to burn off anyway, but welds with less splatter), for plug welds... clean through the hole to the under panel with a die grinder bit before you weld. It will weld if you forget a spot, but you will find it works better if you clean the area at the weld. Lorne

[Blazin]

I have used it, seems to work good. My thing is how much extra protection are you getting. Primers are not meant to take the elements for a long period of time.

[jay6776]

I use it on everything i weld.  i have seen cars come back that were in accidents again and there is alot less rust than the cars I have seen without it. The SEM copper weld through is really nice stuff. And It can not hurt anything useing it.
jay

[Blazin]

I agree it can't hurt to use it. Just one of the things I think about! 

[farmallgray]

What do you guys think about POR15 and Eastwood's rust encapulator? I used the Eastwood stuff on my truck 12 yrs ago and it is starting to rust again after 12 Pa (the road salt capitol of the US) winters. But I don't know how much worse it would be if I hadn't used it. The underside of the floor pans still look good where I coated them.

I had dribbled it into the backsides of the hood front, fenders, doors and bedsides with a brush. I'm thinking next time about hosing epoxy primer in there with an udercoating gun. It won't get much of a test though because the truck isn't going to see the salt anymore.

[jay6776]

What do you guys think about POR15 and Eastwood's rust encapulator? I used the Eastwood stuff on my truck 12 yrs ago and it is starting to rust again after 12 Pa (the road salt capitol of the US) winters. But I don't know how much worse it would be if I hadn't used it. The underside of the floor pans still look good where I coated them.

I had dribbled it into the backsides of the hood front, fenders, doors and bedsides with a brush. I'm thinking next time about hosing epoxy primer in there with an udercoating gun. It won't get much of a test though because the truck isn't going to see the salt anymore.

If you got 12 years out of it thats great when we do rust i tell people 5 years. I have never used por15 but have heard alot of good stuff about it..   Epoxy primmer is not for rust it will be a waste of cash.  I use the SEM rustmort have had alot of good luck with that stuff.