Any idea where I can find "lead-bitumen"? Anybody know of any other names for this substance? Anybody know of any good substitutes? In this article lead-bitumen is used to seperate two layers of MDF. I have some Focal (JM Labs) 6.5" midrange speakers kicking around with a couple of JM Labs titanium tweeters. I would like to put them in a box similar to the one in the article mentioned above but haven't been able to find lead-bitumen anywhere.. Thanks in advance!