Weld thru primers

[marcm2030]

I'm getting ready to do rocker replacement on my 74. Is zinc or copper weld thru better to use. I will be mig welding through pre punched holes. I want to get good penetration of the welds without burning off all the primer. I want to get good protection on the back of the rockers before I can't get to them anymore.



Also is there a certain can primer that good for spot priming. I see epoxy primer or self etching. Not sure witch one is better. I need one I will be able to paint over with quality paint. Probably a base coat clear coat finish. Any help is greatly appreciated.

Thanks,

Marc

 

[sp71eb]

http://www.tcpglobal.com/itemdetail.aspx?itemno=LIK+10011

I'm a bodyman and have used every kind of weldthru primer out there. This stuff is hands down the best. Most zinc and copper weld thru primers require cleaning the paint out of the weld area to get a good weld. This polymer type primer is easily welded through without any additional cleaning of the weld area.

And for epoxy and self etch. Both are direct to prepped metal. Epoxy is good for protecting metal from the elements but must mixed and sprayed from a gun. Self etch comes in two forms. The type that goes under topcoats such as primer surfacer to help it bond to bare metal and rattle can type that is used for quick bare metal coating. Some weld thru primers are a etch type also but are terrible when it comes to welding. Get the like90 stuff and don't look back. Its expensive but one can will do all you will need. A note is that it will be see through when it is on your bare metal. When it dries(takes about 8 hours and doesn't need to be dry to weld) it will be sticky and kinda plastic feeling. Hope this helps.

 

[allenfahey]

Also is there a certain can primer that good for spot priming. I see epoxy primer or self etching. Not sure witch one is better. I need one I will be able to paint over with quality paint. Probably a base coat clear coat finish. Any help is greatly appreciated.

Thanks,

Marc

Primer in a can is never as good as a 2 part primer. If you choose an epoxy primer they usually can double as a sealer. The only thing usually different is the mix ratios. If you choose an etching you have to apply a separate primer on top after the etch has flashed (no sanding between products). Whatever you choose to use look up the TDS(technical data sheet) which will tell you everything about the product from substrates to dry times to mix ratios. If you google "Dupont Variprime TDS" which is a great etching it will look like THIS .

 

[rjrobin2002]

Maybe a dumb question and I weld and paint alot of stuff, but what applications are the weld through primers used for?

 

[allenfahey]

Bare metal between the mating surfaces. You don't apply it for coverage but just coat it.

 

[marcm2030]

Thanks for the info.


Allen,
Is the epoxy/sealer primer better to use. I will just be spot priming for now. Maybe get to painting 6-8months from now. Marc

 

[allenfahey]

Thanks for the info.


Allen,
Is the epoxy/sealer primer better to use. I will just be spot priming for now. Maybe get to painting 6-8months from now. Marc

If you are storing it outside then yes epoxy is better but either one will work. Alot of epoxies are harder to sand compared to a high build 2K primer which goes on top of the etching. You can also epoxy prime it and block sand with 180 and then 2K high build for final priming. No wrong way but make sure to read the TDS for the product you are using. That will also tell you what hardener to use. There is alot of good info in there and can possibly save you money. For an example in the system I use at work, Spies. The hardeners I use is the same for the primer, sealer, and clear. You could then buy a larger size can of hardener which will be cheaper than smaller cans of hardener for other brands that use a different hardener for primer vs. the clear.

 

[marcm2030]

Allen,

Thanks for the advice I really appreciate it.
It's great that people on this site are willing to help others with there expertise.

Marc