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