I was always told it was the starches in the potatoes, but I have no scientific evidence to back that up. back when i was pipe welding, new guys in the shop would get nose bleeds. I figured they weren't used to the welding smoke. we had very poor ventilation in that shop. and fwiw, I learned a great deal of puddle control running 7018. if you want to learn a little bit of everything, look for a used one of these http://www.lincolnelectric.com/en-us/Equipment/Pages/product.aspx?product=K2403-2%28LincolnElectric%29. it's a damn fine welder capable of MIG, stick, TIG, and pulse. I would love to have one in my shop, but we have very very little need for stick or TIG. I welded a ton of pipe (stick) and a crap load of structural (MIG/pulse/stick) with this welder in my old shop. ESAB has a similar machine without all the fancy options that runs like a bat out of hell too. but look for a used one unless you want to drop 5 grand or more.
