Forum / Welding, Forge & Casting
✅ Flux-core welds are full of holes (porosity). Wire? Technique? Machine?
@garage_gabe
Oct 17, 2026 · 1k views
Harbor Freight 125 flux-core, .030 wire, 1/8" angle iron. Beads look like Swiss cheese. Cleaned the metal with a flap disc. What am I doing wrong?
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3 replies
✅ Accepted solution
Three things to check in order: 1) polarity, flux-core wants electrode NEGATIVE and those machines ship set for MIG (positive); 2) stickout, you want 1/2 to 3/4 inch, not the 1/4 you use for MIG; 3) wind. Even a fan across the bench blows the shielding away. Also check the wire: cheap flux-core that has sat open for a year absorbs moisture and pops.
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And drag, do not push. Pushing flux-core traps slag in the puddle.
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It was polarity. Swapped the leads inside the machine and the next bead looked like an actual weld. Thanks.
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