Step 1: Save the kief
Kief is the powder made of trichome heads, the resin glands where THC, CBD and terpenes are produced, and a 4-piece grinder with a screen and an extra bottom chamber collects it as you grind. It has a high concentration of cannabinoids, so start with a pinch smaller than a dime when you use it. More on that in what kief is and how to use it.
Before any cleaning, tip the kief chamber onto a sheet of paper and scrape the screen and walls with the grinder's scraper or a clean spoon. Use a clean tool rather than your fingers, which add oils and moisture, and store kief like flower: in an airtight glass container somewhere cool, dark and dry. The weed storage guide covers containers and humidity.
What you need
- Isopropyl (rubbing) alcohol for metal parts; Vaping360 recommends at least 70%, ideally 90% or higher
- Warm water and dish soap for plastic or acrylic parts
- A glass jar or sealable bag big enough to cover the parts
- A stiff toothbrush, a small soft brush, a toothpick and cotton swabs
- A sheet of paper or a tray to catch kief, and a clean towel
Method 1: Dry brush for routine upkeep
For regular upkeep, take the grinder apart, tap each piece over paper and sweep the teeth, threads and screen with a dry brush. Futurola, a maker of rolling equipment, suggests a quick brush-down every few uses so resin never hardens, and warns that the mesh screen is the most delicate part and bends easily.
How often you deep clean depends on use. Smoke Cartel, an accessories retailer, suggests tapping out loose debris daily and a full clean about once a month, and Vaping360 recommends at least a monthly wash for regular users, plus a clean before a grinder goes into storage.
Method 2: Freeze it when resin is caked on
Cold makes sticky residue stiff and brittle, so it breaks into small clumps instead of smearing (Weedmaps). Put the separated pieces in the freezer for at least 30 minutes; Smoke Cartel suggests 30 to 60 minutes, then tapping them firmly over parchment or a tray straight away, before they warm up. Scrape out what is left with a toothpick and a soft brush, and keep what falls out, since much of it is kief.
The same trick can free a grinder that will not turn. Smoke Cartel suggests freezing a stuck grinder for about an hour, then wrapping a wide rubber band around the lid and base for grip.
Method 3: Alcohol soak for metal grinders
Isopropyl alcohol dissolves oils and natural resins (Wikipedia), which water alone will not shift. Vaping360 and Smoke Cartel both reserve it for metal grinders, including aluminium, stainless steel and zinc ones.
- Take it apart. Separate every chamber and any removable screen, and peel off any rubber O-ring; Smoke Cartel says alcohol dries rubber out and can crack it.
- Soak. Put the metal parts in a jar or sealable bag, cover them with alcohol and leave them for 20 to 30 minutes, swirling now and then (Weedmaps). For heavy build-up, Vaping360 soaks for up to an hour or overnight and sometimes adds coarse salt.
- Scrub. While the residue is soft, work a toothbrush along the teeth, threads and screen, and use cotton swabs in tight corners. Re-soak any stubborn piece.
- Rinse. Rinse every part in warm water until it no longer smells of alcohol.
- Dry completely. Smoke Cartel recommends towelling metal parts dry right away, because water left in crevices can cause white oxidation on aluminium and zinc. Vaping360 then waits at least a couple of hours before grinding again, since damp parts gum up as soon as you use them.
What not to do with aluminium, plastic and wood
- Don't boil an aluminium grinder. Smoke Cartel limits boiling to grinders made entirely of stainless steel, warning that heat can warp aluminium, damage its anodized finish and dislodge the magnets. Anodized coatings crack from thermal stress above 80°C (Wikipedia).
- Skip harsh acidic or alkaline cleaners on aluminium. The anodized layer can be dissolved by high- or low-pH chemicals, which strips the coating and lets the metal underneath corrode (Wikipedia).
- Never use alcohol on plastic or acrylic. Acrylic swells and dissolves in many organic solvents, and stressed acrylic parts can craze when they meet solvents (Wikipedia). Smoke Cartel describes crazing as a network of tiny cracks that clouds the plastic before it breaks. Smoke Cartel, Vaping360 and Futurola all use warm water and dish soap instead; Smoke Cartel soaks the parts for 30 to 60 minutes, then scrubs gently with a soft brush and rinses.
- Don't boil plastic either. Commercial acrylic grades begin to soften at 85°C to 165°C (Wikipedia), and Vaping360 warns that boiling can warp or damage cheap plastic grinders.
- Keep wood dry. Vaping360 advises against washing wooden grinders with water or alcohol, which the wood can absorb; brush them out and wipe them with a damp cloth at most.
Alcohol and drying safety
Isopropyl alcohol is flammable, and its vapour is heavier than air, so keep it away from heat, sparks and open flame while you work (Wikipedia). Rinse until the smell is gone and let everything dry before the grinder goes anywhere near a lighter.
Drying matters for hygiene too. Vaping360 warns that a neglected grinder can grow mould, so let every part dry before reassembling it, to keep bacteria from growing in the damp. The alcohol-and-salt method for cleaning glass is covered in types of bongs.
Replacing a worn grinder
If a plastic grinder has cracked or the screen is torn, a replacement is easier than a repair; Vaping360 notes that metal grinders last longer and survive falls better than plastic or acrylic ones, and they can take an alcohol soak. GasDank's accessories page shows what is on the menu, with same-day delivery across Toronto and the GTA, usually within 1 to 2 hours, and mail order across Canada. Customers must be 19 or older (21 in Quebec), with ID checked at the door.
