I'm not a welder but I can stick stuff together when I need to.  Uncle and Dad were welders.  I have been in welding class in high school, in college, Dad tried to teach me ... I was 30 before I found the problem was I couldn't fry eggs.  Everyone said when it is working right it sounds like eggs frying.  I was frying eggs for a men's breakfast at church when someone explined I didn't know how to fry eggs.

I've had beat into my head the first trick to a good weld is clean up the material you are welding together.  If the area being welded is not clean .... as in no rust, no paint, no nothing but shiny metal clean you cannot expect a good weld.

As long as a weld will hold, 1/4 inch of paint makes it look a lot better :-)