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