Washing marijuana is a process used to make a specific type of hash, bubble hash, a name derived by the way it bubbles when smoked. Hand washing and machine washing are two methods used to make bubble hash and is performed by churning and stirring cannabis flower with ice water. Hand washing is more labor intensive but the preferred method for many that want more precision during the process.

Washing involves adding cannabis flower to bags of ice water which are called “bubble bags” and agitating the mixture that freezes to release the trichome heads from the plant flowers and material. Agitating the mixture causes the trichomes to separate into an icy slurry which is then filtered through screens or mesh bags to collect the trichomes that become hash.