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