I tried all that "soak" time stuff with the toaster oven. I never noticed a difference. Now, all I do is put the spalls in the little tray and lay the other tray on top and crank that baby to 450,500 dgs and let it go all night. I unplug it when I go to work in the morning and take the rock out when I get home in the PM. Usually it is still warm. I've been using those little flea market, Salvation Army, $5 Black and Decker ovens for about 12 years. I wouldn't wrap them, I've seen mine gloe red at nite. I don't know why the plastic knobs don't melt.