A weed grinder helps to grind the bud into the finer material, which makes for a more potent, better smelling, better tasting, cost and time effective rip. The increased surface area from evenly grinding the bud aids to release the aromas and the increased surface area helps make the bud burn more freely. The Trichomes, that give the bud is potency, is no longer brushed away from hand crushing - rather stays with the grinder, hence increasing potency. In a 3 or 4 piece grinder, the trichomes also known as kief or crystals are stored into the bottom chamber, which accumulates after a time and can then be used to sprinkle onto the cannabis for a bigger kick. Some grinders also come with a pollen chamber... the pollen can be pressed into homemade hash. With a grinder less marijuana is needed to reach the same effect, less smoke is inhaled for the same effect, which can translate into substantial savings in cannabis cost to reach the same effect. Time is saved as grinding cuts grinding time by 1/4 of what it takes to hand grind, which means a quicker reward and less time wasted!
A grinder can be made of wood, plastic or metal. However, the quality is distinctively different, as wood and plastic are generally cheaper but wear over time. There is also the potential for the wood or plastic to shape into the weed! There are generally 2 pieces 3 piece and 4 piece grinders with the 3 piece and 4 pieces generally costing more but reduces the bud into finer pieces.
To use... insert the bud around the center... twist 5-10 times... and then shake gently to have the ground weed cycle through the chambers... open - then poor out... and if there is stuck or chunks still remaining... close and twist again both directions. Tap as needed to get the rest of the weed out... smoke and enjoy! :)