Thanks. Really good info. Just a follow up question..... My garage is not attached to my house and is built into a rock hill with the front door being the only opening. Thus, the only ventilation I have is the front door. If I keep it closed while doing welds, will the gasses cause problems? Plan is to do a few quick welds and open the door to air out.
You want ventilation while welding. Get a fan. A bathroom fan would work and run some flexible duct from the fan mounted in an exterior wall to the weld area. Then suck the fumes as you weld. Commercially is very similar to what is done. But good fans to exchange air in building.