For anyone welding out there, Please keep this in mind. Any fumes present MIGHT be harmful when exposed to the heat of the weld. There are numerous chemicals out there that change composition when heated. Tri-chlor-ethelyne, Carbon Tettrichloride, (great for de-greasing) are extremly dangerous to your health. I can not express this enough. My brother is dead because of Tri-chlor. It turns into Phosgene gas when heated above a certain point, and welding aluminum is more than enough to make it deadly. Aside from the fact that it can, and does go right thru the pores of your skin when you get it on your hands. (I have seem guys wash their hands with it) and I don't think any of them are alive anymore. When you get gassed by the phosgene, it attacks the liver, and your liver cannot heal itself as most other body parts. Each time you are exopsed, you get damaged that much more, eventually making your liver hard as a rock. Having Alcahol (drinking) in your liver and breathing trichlor fumes can do terrible damage, too. The alcahol chrystalizes and plugs up your liver. (This is even faster) to kill you. It takes fewer PPM of trichlor to be harmful than it takes to smell it, so you don't even want it in the same building if you can avoid it. Many of the welders I used to work with are no longer with us because of this, and my liver is a bit on the hard side from it, too. I am lucky to be alive after 25 years of welding aluminum in the factory where I worked. I still enjoy it, anyways, I am just more careful. I guess soap and water would be much safer, just rinse it off good. With TIG, wet is OK, it dries before you get there. With MIG, it can cause porosity, which greatly weakens the weld.