Welding sheet metal holes using Brass or Aluminum?

I have heard of guys putting br*** behind sheetmetal for welding up small holes as the weld will not stick to the br***. I dont have any br*** but have a ton of aluminum. Can i use that to back up the sheetmetal when welding?
Im just doing about a dozen small holes and using a 110 mig. 19 ga steel. Thanks

 

Sure, it just gets hot faster.

 

Aluminum will work,but the weld will get into the aluminum and make it a little hard to get off.Try a test piece first to set your heat and go from there.

 

Use copper instead.

 

^^^^what he said copper is best. The heat can melt the aluminium surface and stick it to the weld like harley man said. Also with br*** the heat can cause the zinc to burn out of the metal, again sticking it to the weld or contaminating the weld (pinholes).

 

Copper works the best. Get a short length of copper tubing 8"-10", flatten one end a few inches. Now you can bend it if need be to the contour of the piece your working on and you have a handle to hold it by. You can also take a small piece of tubing, slice down the middle and flatten it and hold it behind the holes or use magnets to hold it in place.