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Weld Thru Primer

Raymond Murray

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Wondering what the crew out there prefers for a weld thru primer. I bought the super expensive SEM CopperWeld which is supposed to be the best; but if you read the small print on the can it says to wipe any excess off because nothing will adhere to it. I noticed that the Eastwood description says just the opposite - prime/paint right over it.
 
I dont really care for copperweld. A quality epoxy primer is just as good IMO. I find it takes the weld easier on initial strike where the copperweld seams to want to sputter. Using copperweld, I have found on spotwelded panels where I'm using my mig, I can use a small wire wheel to clean the copperweld through the center of the hole to the adjacent panel & it is easier to get a confident weld, but theres a lot of areas I just cant get to to get it cleaned off... These areas are especially troublesome because sometimes the heat needed creates a pile that needs ground flat afterwords. To me thats not ideal... Try brushing some mixed epoxy between panels.
As far as topcoating, I scuff it off best I can & use 2 coats of epoxy & haven't seen any issues.

I once saw an axle get shot with epoxy primer after getting blasted. It had the cover removed so the gasket surface could get protected for storage. The oil was drained but center wasn't removed or cleaned and was going to be replaced at a future time. When the time came to pull the unit & clean the housing I witnessed how difficult it was to clean up the caps. The overspray was on top of gear-lube & I was shocked at how well it had adheared. I can only assume it's the ideal protection for clean, prepped steal...
 
I also noticed that many of the bolt on brackets and braces have seam sealer underneath them between the body and the bracket. What a mess sometimes.
 
There is also a heavy green primer underneath the red final primer. Dont know what it is; maybe a heavy epoxy or polyester used to smooth out the poor metal forming.
 
I always liked the 3M weld-thru primer, but I imagine it's pretty expensive by now as all the 3M stuff is. The last stuff I used was made by U-pol. To be honest I've been trying to avoid situations where I need a weld-thru coating in the first place because they never seem to do what they're supposed to do, at least long term.
 
3M stuff is insanely overpriced. I just tried some Eastwood stuff. Pretty OK.
 
Difficult to purchase. The Spray Max 3680001 is also nice but equally hard to find.
 
100 bucks for a gallon at grainger......life time supply........brush it on

I just got a new gallon, broke it into 4 quarts so it doesn't go bad in the can.......gave my buddy a quart

(6) Bloxide Weldable Primer - YouTube

24100_bloxide_gallon_700x-jpg.jpg
 
The truth is, weld through primers are very easy to spray, and often harder to weld to. I've tried a few ( by no means an expert) and the results were, meh.
 
...or what a blonde uses to bleach her hair.
 
The truth is, weld through primers are very easy to spray, and often harder to weld to. I've tried a few ( by no means an expert) and the results were, meh.

bloxide welds like normal, let it dry........ I usually put it in the sun or run a heat gun on it when in a hurry
 
I also pour a little into seams, and blow it into crevices with compressed air......it's an awesome rust preventer

its very thin and watery
 
Grabbergreendream. Did you say that you weld to epoxy primer without grinding to bare metal? I've never tried that. Hmmmm. Learn something every day.
 
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