Just tried working with weld thru primer for the first time and was not particularly impressed with the compatibility of the primer with the welding process (MIG).
I was laminating a 2-1/2 inch wide strip of 1/8 mild steel onto a wider strip of 1/8 mild steel using plug welds set in 7/16" dia holes propagating along the center of the 2-1/2 inch strip, and then following that with skip welds along the edges of the 2-1/2" strip.
Because the welded assembly is going to be exposed to the elements and not completely sealed along the edges, I decided to try applying a coat of weld thru primer to the each mating face of the steel strips to mitigate the development of rust between the strips. The finished assembly would be painted on the outside as well after welding is complete.
The zinc rich primer is supposed to combine with the puddle to intruduce an element of corosion resistance to the actual weld but I was mostly wanting to control corrosion caused by any moisture that might get between the two strips as opposed to treating the actual welds as suggested by the tech literature for the product.
It's implied that using the product won't compromise the quality of the welds produced but I found that the volatiles in the dryed primer gased off and boiled out through the puddles causing al kinds of holes and "solidified geysers" in the welds, particularly in the plug welds where the expanding gases can only escape directly thru the puddle.
By the time I was done with this project I had taken to removing the primer from the prepared strips altogether.
Just wondering if anybody here has any experience with weld thru primers and any observations to offer pro or con.
Thanks for any reply,
Dennis van Dam