hey sicka.... i do batches of BHO and i just use any can to tell you the truth, you will never now the refinement plus its full of hydrocarbons anyway....
What they mean is cooking it over after they have evap'd the butane out, this can be done in an oven on very low heat over a period of time, or you can just vacume purge a few times untill you see it buble and turn itself nearly inside out. Vacume purging is hell quicker but if ya gots the time a fews hours in the oven depen how low you can get it but simply spreading the oil load over a bowl and "getting its surface area maxed out you will gain good results in filtering your already evap'd BHO hope this helps if i wasnt such a stoner i would link you up but as of now im knocked out by my very own BHO....how ironic lol