I was going to post on the Home Decorating forum, thinking it would receive some good feedback, then thought to check out the garden forums. And wowza! Here you all are! I bought this, uh, treasure about 15 years ago, probably for a dollar. It has sat under the eaves of the house while the children grew, and now it is time to make some garden art! It was heavily rusted when I bought it, and that hasn't changed.
Today, I sanded with sandpaper "for metal" and after wearing out my fingers and sweating up a storm, moved to the wire brush. Yes, I am a novice in these things! I would love to know if I need to scrub every last sign of rust off of it before painting or just get it fairly smooth (but with all the chunks of rust off). This photo shows it mid-way through the process. After lots of wire scrubbing, there remains surface rust, but it feels fairly smooth.
Also, any ideas what it might be from?