Primer Question.
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Elder User
Joined: Sep 2006
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From: Katy(Houston), Texas
Primer Question.
I went to a auto paint shop a few days ago to buy some weld through primer and while I was there I figured I should pick up some primer to paint the parts that I will be welding. These parts will not be accessable once the panel is welded in (I hope that makes sense). The guy there sold me self etching primer. When I got back to work I did a little research on the subject but I'm not sure if I got the correct thing for my situation. It seems like it will work but should I have gotten epoxy primer for those inner panels or will self etching work or would regular hardware store type primer work. I was concerned about the possibility of moister build up between the panels and rust forming.
Am I worring about something that I shouldn't be or should I really be concerned about the bare metal from sanding off for the spot welds that wont be seen? The primer wasn't cheep so just want to be sure Im not wasting my money.
Thanks!
Am I worring about something that I shouldn't be or should I really be concerned about the bare metal from sanding off for the spot welds that wont be seen? The primer wasn't cheep so just want to be sure Im not wasting my money.
Thanks!
Hotshot
Joined: Oct 2009
Posts: 16,135
Likes: 4,735
From: Burbank, WA
For maximum protection on hidden areas, epoxy primer is the way to go, definitely. Self-etching is good stuff, but is intended to be top coated with epoxy or primarily urethane fill primer.
All that said, it really depends on how you intend to use the truck, your weather conditions, and where these hidden areas are as to whether or not you should be concerned with coating the areas. In a dry climate, it may coat itself with some benign surface oxide and be fine for years and years. If it's an area that will be wet a lot, then it would be best to coat them with something.
Understsand that it took 50-60 years to become as big a problem as it is now, and there was never the kind of assembly quality or care given to these trucks as we will now that they're restored. You'll need to decide how crazy you want to get with coating the hidden areas. But if you do decide to coat them, I'd exchange the self etch for epoxy. If you're going to do it, do it the best you can.
All that said, it really depends on how you intend to use the truck, your weather conditions, and where these hidden areas are as to whether or not you should be concerned with coating the areas. In a dry climate, it may coat itself with some benign surface oxide and be fine for years and years. If it's an area that will be wet a lot, then it would be best to coat them with something.
Understsand that it took 50-60 years to become as big a problem as it is now, and there was never the kind of assembly quality or care given to these trucks as we will now that they're restored. You'll need to decide how crazy you want to get with coating the hidden areas. But if you do decide to coat them, I'd exchange the self etch for epoxy. If you're going to do it, do it the best you can.
Junior User
Joined: Feb 2011
Posts: 98
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From: Waterford, Michigan
I agree with Wayne
Epoxy is the way to go.
Just make sure if this is a part to be top coated you cover the epoxy with a fill primer. The epoxy remains somewhat sticky and can load up your sandpaper if you end up needing to scuff it because you waited beyond the recoat window.
Each paint manufacturer and product line can have different recoat/drying windows. Ask for the data sheet while your at the paint store. If they are a reputable dealer they will have no problem printing one off for you.
Good luck,
Rich
Epoxy is the way to go.
Just make sure if this is a part to be top coated you cover the epoxy with a fill primer. The epoxy remains somewhat sticky and can load up your sandpaper if you end up needing to scuff it because you waited beyond the recoat window.
Each paint manufacturer and product line can have different recoat/drying windows. Ask for the data sheet while your at the paint store. If they are a reputable dealer they will have no problem printing one off for you.
Good luck,
Rich
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Elder User
Joined: Sep 2006
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From: Katy(Houston), Texas
Thanks for the responses.
For now these should be parts that aren't exposed once welded up. In particular Im talking about the inner cab corner where it welds to the cab and then where the inner is covered by the outer corner.
Ok, I'm planning to take it back and get some epoxy primer on Monday.
For now these should be parts that aren't exposed once welded up. In particular Im talking about the inner cab corner where it welds to the cab and then where the inner is covered by the outer corner.
Ok, I'm planning to take it back and get some epoxy primer on Monday.
Junior User
Joined: Feb 2011
Posts: 98
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From: Waterford, Michigan
Don't missunderstand.
The etch primer has its place as well. It's great for bare smoth metal. It has acid in it that etches the metal and gives the primer some teeth to bite into the metal.
With the epoxy you actually don't want the metal real smooth. Run over it with your DA with some 80 grit and wipe it with some prep solvent. You'll be good to go.
Don't forget to ask for the data sheet. It will help you determine the best mix ratio for your application and recoat windows.
Rich
The etch primer has its place as well. It's great for bare smoth metal. It has acid in it that etches the metal and gives the primer some teeth to bite into the metal.
With the epoxy you actually don't want the metal real smooth. Run over it with your DA with some 80 grit and wipe it with some prep solvent. You'll be good to go.
Don't forget to ask for the data sheet. It will help you determine the best mix ratio for your application and recoat windows.
Rich
Welder User
Joined: Feb 2009
Posts: 5,269
Likes: 50
From: northwest MT
Yeah, epoxy will work better if you aren't top coating it. When i want to prime small hidden areas, I just use a paintbrush and slobber it on the welded seams. Do a couple of coats. Nobody will ever see it, and you will have peace of mind....
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