Some say they do it to make the weed last longer, some say it's too harsh without it. I say just pack in as much as you would minus the amount of tabacco that would be there. I don't smoke big stonking cones, I pack about 3/4 full, pull it all and leave no "deads" in the chamber and then I hold it without coughing until I blow out next to nothing. Then I have 10 more. It hurts me to watch cunts pack a rainforest, barely pull it, cough their ring up and blow the bulk of the cone out of the bong as "dirty" or "dead" smoke. what a waste!