when you  smoke hemp it leaves a residue 
 tar   inside   the   machine,  which  is 
 extractable  with  the help of  a  metal 
 rod. be wary however, that  the hemp tar 
 is  not as  viscous as you may  think... 
 it'll quickly get  on  your fingers  and 
 boobs...  and it's hard to get off. very 
    sticky business indeed. most people   
 just   get   rid   of   their   machines