halfdome, Danny wrote:Here's a photo of the side that sat out in the direct sun yesterday for 5 hours. It was a clear 80+ degree day. It's just as flat as the day I made it.Danny
Our low temperature yesterday was 83 degrees.

When I installed the (floating) aluminum it was 40 degrees in my garage. Lately, as it's been near 110 degrees, there is very slight oil-canning in my aluminum. You wouldn't know it though unless you push on it.
As Danny said, I've seen examples of direct applied aluminum in our area using contact cement or outdoor carpet cement, and they don't seem to have any delamination or oil-canning.
I guess it more of a "pick-em" as to how you do it.