Cutting copper usually creates these sharp-edged burrs, and they need to be removed for your soldering to work properly. Clean dirt and corrosion off the outside of the pipe end with a 120-grit ...

longer than the damaged section. The key to a good joint when soldering copper pipe is to keep the inside of the pipes dry, ...

Instead of buying some job specific wire mesh, just use a copper coated scourer to clean your soldering iron tip. Usually used for cleaning pots and pans, these little guys can be picked up at ...