Just realized a wet sponge trowel can save a hot pour

Had a driveway job in Tempe last week where the mix was setting up way too fast in the sun. My usual timing was off by a full hour. On a whim, I grabbed a clean sponge, soaked it, and ran it over the back of my steel trowel before each pass. It added just enough moisture to the surface to get a slick finish without pulling up fines. I was sweating bullets but it worked. Anyone got other tricks for a fast-setting slab in direct heat?