Splinter - In this case, since the substrate was already as flat and stiffer than my melamine cauls, I didn't need a bottom caul. I didn't use a top caul either since the veneer didn't overhang the substrate (it was the opposite) and because of the slight variations in veneer thickness. A top caul would have bridged the the thinner veneer somewhat. I did end up with some surprises when I pulled the panel from the press. More on that in the next post.