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