Below is an excellent example of how not to build a steam box for wood bending. I made this intending to use it in making a specific curved wood design for my Sconce project also seen on my website. The wood I was determined to bend was too dense for a steamer like this and the box split apart after a couple hours of use.
Tip number one is do not use wood glue for a steam box; the steam will dissolve it.
Tip number two is use lots of screws (definitely more than two per board). Also, make sure that you pre-drill to avoid any hint of splitting.
Tip three, do NOT use wood that’s all ready warped, split or bent. This is probably obvious to most, yet apparently not to me.
Last tip is do not try to bend wood that is denser than the wood the box its self was made from.
It was as entertaining as it was disappointing to watch my steam box pop apart at the seams minute after minute. Oh the joy of scrambling to screw the various pieces back together as they burst open one after the other, engulfing my hand in searing steam. Even better was the joy of attempting method after method of bending only the slightest curvature to your exotic, hand-selected, Sapelle wood only to be left with half-charred, water damaged, awkwardly warped sticks of crap. Then to use those charred sticks to make a mediocre looking sconce that scantly resembles your very elegant original thought of how it should look.