Hello, I have been having a few issues with aluminum lately, the worst being pitting in the weld, that has been driving me nuts. All of these issues only happen with a newer welder that I bought. THe welder in question is a 250 Snycrowave (sn# lg480049l). T weld looks ok on the outside, a little grainy and dull, but the bead is filled will gas pockets that only come out when ground down. Material is 6061 or cast mold plate, I am using both 4043 and 5056 and have the same issues. thicknesses vary from 1/4 to up to 4" thick. some times I pre heat sometimes not. I have tried pure, thoriated and ceriated and have the same issues. I like to weld hot, but very my amps as needed with the pedal. Filler and base materials cleaned with acetone and SS brush or scotch brite pad. Attached is a picture of the pitting.

I will try to make a sample tomorrow with more accurate info for amperage, material, cleaning, rod, ect with a before and after grinding.