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