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