Check out TECH SHOP SAN JOSE some tops on how to create better welds using good prep and how to avoid destroying your material.
Step 1: Strip Platting
in order to start the weld you need a clean surface for the electricity to jump to. as well as having some problems with some coatings burning and inhaling the fumes. so it makes it better in both days. there are many ways to strip coating for metals I have another instruct able for that.