10. After a little practice, we were able to produce some good welds. When welding aluminum, the gas coverage is very important to avoid contamination. Always push the puddle to ensure that the gas is on and in front of the welding pool. This will help you produce a weld more like the one pictured on the left. On the right, you see how the weld has a blackened or burned appearance; this is the result of a weld that's been pulled rather than pushed. This is the most important tip when it comes to MIG-welding aluminum. With some practice of pushing the welds, you'll be on your way in no time.