Hey guys I was wondering, does weld through primer absorb moisture like regular primer?


Thanks, Dave

 

I just used some for the first time recently. It is not a surface-building type of primer. It appears to be filled with something shiny like aluminum and dries to a surface that seems to be less porous than sandable primer. I used it for plug-welding (90-degree) flanged joints through holes, but I think it was intended for spot-welding, with the aluminum being there to avoid insulating the joint. I think the whole idea is to seal up as much of the aread around the joint, so as to reduce corrosion. With this in mind I would expect it does not absorb moisture, but I am interested in other people's experience/opinions.

 

thought I'd bump this thread up. I just bought some "Du-Pol" weld through primer. I intend to cover the surfaces between panels that I need to spot-weld together. However, and perhaps I'm overthinking this, but I'm wondering if that will be enough for durability. Afterall, it's an inner fender panel. I suppose I'll have to scuff and prime the whole area afterward with some self etch? or chassis black? Is using wax&grease remover before the weld through overkill?

 

always use a good cleaner before any application to include weld through primer as it still needs to chemically bond with the metal. This stuff is still a sleeper- went to the local welding supply store to get some and when i asked you'd thought I was the biggest idiot alive- finally a smart-a$$ed employee/expert sarcastically commented that "all primer is weld through". big laughs then i shook my head, praised their collective ability and knowledge and left for the paint store.

the primer, from what i understand is more of a coating that impedes the collection of water and formation of the chemical reaction that causes rust- primarilly the latter. the weld itself and immediate area is not protected that well but once immediately out of the destruction it works well (more resistive to the heat as well) which is better than other products. I think butt welding where you can treat all of it after the weld is worth it whenever possible. weld through is not a topcoat quality seal- probably similar to etch primer that leaves a protective residue but doesn't seal that well.

Self etch is expensive as is epoxy primer but if i have the choice it's epoxy. Self etch means less scuffing is needed to spray it...epoxy needs more surface prep but is the bomb...pricy to do both. Epoxy needs to be sprayed within 12-24 hours usually or you have to scuff it again.

What you put as your first coating is the most important layer you will add- epoxy is best unless you go with a por 15 or easton product that has a polyurithane base and doesn't need or want primer under it. thats the best bet i think and you will not have to worry about rust under there for a very, very long time.

 

the welding primer is a zinc formula. So your putting a protective layer of zinc over the bare metal. This keeps the area free of contaminents. This gives you a cleaner and better weld. If your doing a butt joint, the primer will protect that area your not going to see. Eastwood sells zinc undercoatings that are used to spray the inside panels of your vehicle to prevent oxidation.

 

eastwood does? did n't know that...always used the por zink stuff. good to know since eastwood is a sponsor.