How to Clean a Grinder and How Often to Do It

Have you had your grinder for a while without cleaning it? Take a look at the teeth. There is probably a layer of hard, sticky resin in the gaps between them. That is why the grinder turns more stiffly than before and grinds less evenly, and luckily it is quick to fix. Here we go through what you need, how to clean your grinder step by step and how often it is worth doing.

If you are new to grinders, you can start with our guide on what a grinder is and how it works.

What you need

You do not need any special tools to clean a grinder. Most of it is probably already at home:

• Isopropyl alcohol, ideally 90 percent or stronger. You can find it at pharmacies and hardware stores.
• A small brush, such as an old toothbrush or a stiff paintbrush.
• Cotton buds and toothpicks for tight spaces.
• A small bowl or a zip bag for soaking.
• Kitchen paper.

It also helps to have a coin and some room in the freezer, more on that below. Isopropyl alcohol is highly flammable, so clean the grinder in a ventilated space and away from open flames.

How to clean your grinder step by step

1. Empty the grinder

Grind what is left and empty every chamber. Tap the grinder against a sheet of paper to get the last bits out. If you have a four-piece grinder, collect the kief from the bottom chamber before you start, so it does not end up in the sink.

2. Put it in the freezer

Many people skip this step, but it makes a big difference. Take the grinder apart and put the parts in the freezer for 20 to 30 minutes. The cold makes the sticky resin hard and brittle. Then tap the parts against a hard surface, and a lot of the resin comes off before you have even started scrubbing. Kief stuck to the walls also becomes easier to loosen.

3. Brush away the loose material

Brush the teeth, walls and screen with the toothbrush while everything is still dry. A lot of the loose material comes off at this stage, which makes the soak more effective.

4. Soak the metal parts

Put all the metal parts in isopropyl alcohol for 20 to 30 minutes. If the grinder is only slightly dirty, 20 minutes is enough, but if it has not been cleaned for months you can leave it longer. Acrylic or plastic grinders should not be soaked in alcohol, as the material can be damaged. Use warm water and a little washing-up liquid instead.

5. Scrub and rinse

Go over everything with the toothbrush again. The resin should now come off much more easily. Use cotton buds for the screen and tight corners, and toothpicks between the teeth where the brush cannot reach. Then rinse all parts thoroughly in warm water until they no longer smell of alcohol.

6. Let everything dry completely

This step matters more than many people think. If you put the grinder together while it is wet, the metal parts can start to corrode and the threads can stick. Lay the parts on kitchen paper and let them air-dry properly. One to two hours is usually enough.

How often should you clean your grinder?

It depends on how much you use it. If you use your grinder every day, a quick brush every other week and a proper soak once a month is often enough. With regular but not daily use, a thorough clean every four to six weeks is usually about right. If you only use it now and then, every three months may be enough.

A good rule of thumb: when you have to use more force than usual to turn the grinder, it is time. Do not wait until the teeth are visibly clogged.

Save the kief

Kief is the fine powder that collects in the bottom chamber of a four-piece grinder. It is made up of trichomes, the tiny glandular hairs on the flower where the plant produces most of its cannabinoids and terpenes. With CBD flowers, this means the kief is rich in CBD and aromatic compounds.

Kief can only fall through if the screen is clear. A clogged screen means most of it stays in the grinding chamber and gets mixed with the rest of the ground material. The freezer trick above is especially useful here: after freezing and a few taps, you often find more kief at the bottom than you expected.

How the material affects cleaning

The material your grinder is made of decides how you should clean it. You can find our models among our grinders and mixing trays.

• Aluminium is the easiest to clean and handles regular soaking in isopropyl alcohol best. The surface stays in good condition and does not absorb odours over time.
• Zinc alloy is common in cheaper grinders and is fine to clean. Check for sharp edges or a coating that looks like it could flake. If you see that, replace the grinder rather than keep using it.
• Acrylic and plastic are the hardest to clean. Skip the alcohol and use warm water with washing-up liquid. Plastic also scratches more easily, and resin gets stuck in the scratches.

If you use your grinder often and clean it regularly, a good-quality aluminium grinder is worth the money. It will last for many years.

After cleaning

Once everything is dry and assembled, the grinder should turn noticeably more smoothly, and the teeth should grind evenly again. With CBD flowers you will also notice a cleaner aroma, without traces of old resin. If you use a vaporizer, an even grind matters even more, as a dry herb vaporizer works best when the material is evenly ground. If you are thinking about getting one, you can read our guide to dry herb vaporizers.

Sources

• Livingston, S. J. et al. (2020). Cannabis glandular trichomes alter morphology and metabolite content during flower maturation. The Plant Journal, 101, 37–56.
• Tanney, C. A. S. et al. (2021). Cannabis glandular trichomes: a cellular metabolite factory. Frontiers in Plant Science, 12, 721986.
• National Center for Biotechnology Information. PubChem: Isopropanol.