Preventing Warping when Roasting at High Temperature I like to roast in a gas oven at 400F for extended periods.  Ex: I will cook large batches of bacon at 400F for about 35 min, and large batches of Brussels Sprouts at 400F for 60+ min (with stirring).  I have a large, gas convection oven.

A challenge I experience is my pans warping.  This can cause them to suddenly deform in the oven, flinging food out of the pans and causing burns in the oven.

I recently got a set of 18-gauge stainless steel baking sheets, an upgrade from a thinner, cheaper set I had before.  These have helped some, but I still experience warping.  My questions:


Would aluminum be better than stainless steel for purposes of preventing warping?
Is the use of metal inevitably going to risk warping? (i.e. do I just need to give up and switch to glass or something?).  
Do I just need an even higher gauge (e.g. maybe 10?).  (note: I like to use baking sheets that are at least 20in x 14in, and it's hard to find sheets this large at gauges higher than 18).  
Am I somehow missing something else entirely?


I've read that having fewer raised edges can reduce warping.  But, I really need the pans I use to have all four edges raised about an inch.
The bottom surface of the pan will expand as it heats. The edges will also expand but they won’t be able to expand as much as the bottom surface. This will cause the warping, even cracking.

As you have mentioned one way of avoiding this is having one or two edges, as the cookie sheets would have. These pans will not create such tension as the surfaces of the pans expand.

In your case however I think you need thicker pans that can withstand the tension.