Hi guys and gals, Been a long time lurker on the site! Over the years, I have had many rust heaps that I wish I could have fixed...But never had the bottle to try and fix anything...So here I am! I have a brand new welder, and im determined to learn the art....including making decent repair patches and doing a nice job. Here is my problem: I know there is surface rust between the seams. Do I have to bust open all the seams to brush the rust out? or can I get away with using epoxy mastic to seal the lot up (after cleaning and patching the visible areas) Thank you all!