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hosocat Samba Member
Joined: January 13, 2005 Posts: 109
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Posted: Wed Oct 08, 2014 1:43 pm Post subject: Weld through primer procedures |
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I apologize in advance if I'm asking a question that's already been answered. I did a quick search and didn't find an answer, so here goes.
When I weld my new floor pans onto the tunnel of my 73 SB convertible, I am going to prep both the tunnel and the sanded edges of the new floor pans to a shiny surface, then spray with weld through primer before I weld.
Should I spray all exposed surfaces on the tunnel and the new pans, or should I just spray weld through primer on the spots where I'm going to spot weld the pans onto the tunnel? Also, after I've welded should I then sand off all remaining weld through primer before I prime again and finish with final coating, or should I just paint over the weld through primer, or does it not matter? Thanks for tips. |
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theKbStockpiler Samba Member
Joined: July 07, 2012 Posts: 2316 Location: Rust Belt
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Posted: Wed Oct 08, 2014 6:19 pm Post subject: |
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Weld through primers claim to fame is when you you want to protect metal that will be enclosed after you weld it. It is stated as being better than nothing. If you use regular paint and or primer it will burn off and you will have bare metal that you don't have access to. _________________ 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. |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21518 Location: Oklahoma City
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Posted: Wed Oct 08, 2014 6:36 pm Post subject: |
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theKbStockpiler wrote: |
Weld through primers claim to fame is when you you want to protect metal that will be enclosed after you weld it. It is stated as being better than nothing. If you use regular paint and or primer it will burn off and you will have bare metal that you don't have access to. |
Also...the problem with welding through any primer...even weld through primer...is that it gets impurities into the weld puddle. It makes the weld weak and prone to rust and pores.
Its, best to prime the metal surface with weak basic primer, clamp in place.....then wipe well with acetone where yiu are going to weld.....both sides. Then wire wheel it with a CLEAN steel only ...not stainless wire.....nit a wire wheel that has been previously used on other metals like stainless or brass or aluminum. It puts metals into the surtace which ckntaminate the weld.
Will all of this stop you from welding? No.....but it can cause rust apots after a period of time. Best to do it as correctly as possible.
Ray |
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fh4ever Samba Member
Joined: December 27, 2010 Posts: 12 Location: sc
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Posted: Wed Oct 08, 2014 6:49 pm Post subject: |
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there is another school of thought....I have always used seam sealer on both sides to seal the joint. However, I just bought a rattle can of the weldable primer...I thought I might just give it a try. The salesman did tell me the primer contains zinc for welding conductivity and immediately around the weld area will burn off. so I will still use the seam sealer. |
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kman Samba Member
Joined: November 04, 2005 Posts: 739 Location: Michigan
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Posted: Fri Oct 10, 2014 3:12 pm Post subject: |
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Yeah it's more than 90% zinc. Scuff it off and epoxy before seam sealing. |
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esde Samba Member
Joined: October 20, 2007 Posts: 5969 Location: central rust belt
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Posted: Fri Oct 10, 2014 5:56 pm Post subject: |
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I use the the copper weld through primer a lot. It is great for stacked joints, where you have two layers clamper together, that are spot / rosette welded, like the pan/ tunnel intersection. My technique is: grind smooth, clean, prime with weld through along the entire seam. Then clamp/ screw the parts, then weld in. When I can, I prime with epoxy before using seam sealer, then seam seal, then epoxy again. Whatever you can do to seal the joint, and coat the metal inside. |
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hosocat Samba Member
Joined: January 13, 2005 Posts: 109
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Posted: Mon Oct 13, 2014 3:27 pm Post subject: |
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I bought a 12 oz can of weld through primer. Our local OReilly's had it in stock for $10 a can, which seemed reasonable compared to the $18-20 I was seeing on the internet. I don't know if all OReilly's carry it. My local one has a paint center where they mix paint, so they may carry a more extensive supply of auto paint supplies. |
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ekacpuc Samba Member
Joined: December 08, 2010 Posts: 1414 Location: ketchikan alaska
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Posted: Sat Oct 18, 2014 7:42 pm Post subject: |
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Just prime, let dry and then weld.
At home I use zinc rich weld through primer.
I'm a welder (get paid to do it) and everything we weld is primed with weld through primer. If you get pin holes grind the weld out and do it again. I've never had a problem.
The primer making a weld more rust prone is bs. That's why we use the stuff... To prevent rust. I'm a shipyard welder, we service the same ferries year after year and if the weld through primer didnt work we'd know... Granted primer isn't top coat so ya still have to top coat or it will rust.
Btw every weld gets tested that I make. If there where problems I'd know. |
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ekacpuc Samba Member
Joined: December 08, 2010 Posts: 1414 Location: ketchikan alaska
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Posted: Sat Oct 25, 2014 10:48 pm Post subject: |
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ekacpuc wrote: |
Just prime, let dry and then weld.
At home I use zinc rich weld through primer.
I'm a welder (get paid to do it) and everything we weld is primed with weld through primer. If you get pin holes grind the weld out and do it again. I've never had a problem.
The primer making a weld more rust prone is bs. That's why we use the stuff... To prevent rust. I'm a shipyard welder, we service the same ferries year after year and if the weld through primer didnt work we'd know... Granted primer isn't top coat so ya still have to top coat or it will rust.
Btw every weld gets tested that I make. If there where problems I'd know. |
I was incorrect. Some weld through primers apparently suck! The company I work for ran out of the normal primer and used this other weld through primer. It really really sucks! Pinholes every time.
I'd spray scrap steel and test the primer before dedicating myself to it. If you get pin holes avoid using where you're gonna weld.
My father has a jeep he's doing body work on and is using some weld through primer and it's fine. The stuff we use to weld at my work was fine. Some weld through primers suck. Just be carefull. |
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