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