[ebranden]

What causes porosity in welds?
The most common, to the real odd ball stuff, that gets overlooked during set up, before welding starts

[Greg From K/W]

If your using welding rods then dirt and rust will cause it. As well as oil and grease. Water saturation in the coating on the rod.

If your talking about mig welding dirt on the base metal could do it. Rust might but you never know. Lets wait and see what the others say about it.

[BlackCatBonz]

What causes porosity in welds?
The most common, to the real odd ball stuff, that gets overlooked during set up, before welding starts

Arc length too long, dirty material, bad technique

[TheExpert]

Porosity in welding is a result of dissolved gases or gases released during the welding process, being trapped in the metal when there is insufficient time to escape prior to solidification.

[karir]

another big cause of porosity is cold starts! what i mean is striking an arc and moving forward too quickly. when u strike,you need to wait a second for arc to stabilize,then move your rod in a circular motion in place a couple times and then progress. this should prevent any chance of creating porosity.

[Jarrod]

1. Clean the weld area of all rust and mill scale.
2. Use only a newly opened box of rods.
3. Keep a tight arc.
4. Follow other tips given in this thread. There ia alot
of good advice from others.