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How to Keep Your Chemex Clean

A simple guide to cleaning your Chemex, from daily rinses to deep cleaning for tough stains.

The Chemex is known for its cool shape and the clean coffee it makes. It's made of a special glass that doesn't add any flavor. This means you only taste the coffee beans.

A beautiful, sparkling clean Chemex coffee maker sitting on a sunlit kitchen counter.

But if the glass is dirty, your coffee won't taste pure. This guide shows you how to clean it. It covers everything from a quick daily rinse to a deep clean for tough stains.

Why a Clean Chemex Is Important

Sometimes, new Chemex users say their coffee tastes bad, like burnt or sour. This is usually because of how it was brewed. For example, sour coffee often means it brewed too fast.

Bitter coffee can mean it brewed for too long. A dirty Chemex can cause both of these problems.

  1. Oily Buildup: Coffee beans have oils that stick to the glass. If you don't clean it, the oil gets old and tastes bad. This old oil will ruin your next cup of coffee.
  2. Mineral Buildup: If you use hard water, you'll see a white film called scale. This scale means your water has a lot of minerals in it. These minerals can make your coffee taste chalky or bitter. In automatic brewers like the Chemex Ottomatic, this scale can clog the machine and stop the water from getting hot enough.
Pro Tip: If you notice a cloudy, white film (scale) in your Chemex, it's a sign of hard water. Cleaning it is a temporary fix; switch to filtered or bottled water to prevent mineral buildup from happening in the first place.

If you see scale inside your Chemex, it's a warning sign that you're using hard water. Cleaning the scale is only part of the fix. You should also start using filtered or bottled water.

Before you change your coffee grind or how much coffee you use, make sure your brewer is clean. A clean Chemex is the first step to making good coffee.

A Simple Cleaning Schedule

The best way to keep your Chemex clean is to have a schedule. How often you clean it depends on what you're trying to remove.

Table 1: The Chemex Cleaning Cadence

Frequency Method Purpose
Daily Hot Water Rinse or Soap & Water Removes fresh coffee oils.
Weekly Deep Clean with a cleaner like Cafiza Removes tough, brown coffee stains.
As Needed Deep Clean with Vinegar Removes white, cloudy mineral buildup.

Step 1: The Daily Rinse

This is the most important thing you can do. A quick one-minute rinse right after you use it will prevent most future stains. Do it while the glass is still warm.

A person using a long bottle brush to clean the inside of a Chemex with soapy water.

You can just use very hot water if you do it right away. But washing with a little soap and water is even better.

Is It Okay to Use Soap?

Some people worry that soap will leave a taste behind. This can happen, but that doesn't mean you should avoid soap completely.

Coffee oils don't wash away with just water. You need soap to break down and remove the oils, or a thin film will build up over time.

Important: Always use unscented dish soap. The "soapy" taste people worry about is almost always from leftover fragrance, not the soap itself. Rinse thoroughly until the glass is squeaky clean.

The "soapy" taste usually comes from scented soaps or not rinsing well enough. The real problem is the fragrance, not the soap. So yes, you should wash your Chemex with unscented soap and rinse it out really well.

Your Daily Cleaning Routine

Warning: To prevent thermal shock, which can crack the glass, never put a hot Chemex directly into cold water. Let it cool down for a few minutes first.
  1. Let it cool a bit. Never put a hot Chemex in cold water because it could crack.
  2. Take off the wooden collar and leather tie before washing. If the wood gets wet a lot, it can warp, crack, or get moldy.
  3. Add a few drops of unscented dish soap and fill it halfway with warm water.
  4. Scrub the inside with a long bottle brush. This is a must-have tool because of the Chemex's shape. Make sure you scrub the bottom, middle, and neck.
  5. Rinse with warm water until all the soap bubbles are gone. The glass should feel squeaky clean.
  6. Let it air dry, preferably upside down on a rack. Don't put the wooden collar back on until the glass is completely dry.
  7. You can put the glass part in the dishwasher (without the collar). But washing by hand with a brush usually works better.

Step 2: Deep Cleaning with Vinegar

This is a special deep clean for a specific problem. You don't need to do this every day. Use this method only when you see mineral buildup.

A cloudy Chemex coffee maker filled with a vinegar and water solution to remove mineral scale.

When to Use Vinegar

If your Chemex looks cloudy or has a white film, you have scale from hard water. To remove these mineral spots, you need to use something acidic. Plain white vinegar is cheap and works great for this.

How to Clean with Vinegar

  1. Take off the wood collar and leather tie.
  2. Mix one part white vinegar with one part warm water.
  3. Fill the Chemex with the mix and let it soak for a few hours. For really tough scale, you can leave it overnight.
  4. Pour out the vinegar mix. Use your bottle brush to scrub off any leftover spots.
  5. Now, you need to get rid of the vinegar smell. Wash the Chemex with unscented dish soap and warm water.
  6. Rinse it well and let it air dry.

Does Vinegar Dissolve Coffee Grounds?

People often ask this, but it's about getting rid of grounds, not cleaning. The answer is no, vinegar doesn't really dissolve coffee grounds.

You might see tips online about using vinegar and baking soda to clear a drain. This creates a foam that can loosen a clog, but it doesn't dissolve the grounds. Don't put lots of grounds down your sink.

Plumbing Alert: Never wash large amounts of coffee grounds down your sink. They do not dissolve and can combine with oils and grease to create serious plumbing blockages. Always dispose of them in the trash or compost.

They can cause serious blockages. It's better to put them in the trash or compost.

Step 3: Getting Rid of Tough Coffee Stains

This is another kind of deep clean, and it's for a more common problem.

When to Use This Method

If your Chemex isn't cloudy but has a sticky, dark brown film, you have old coffee oil stains. Daily soap and water won't be enough to get this off.

Cleaning Science: Remember this simple rule: Use an acid (like vinegar) to fight mineral buildup (scale). Use an alkaline solution (like baking soda or Cafiza) to fight acidic coffee oil stains.

We learned that acid (vinegar) fights minerals. But coffee oil is also an acid, so to clean it you need to use an alkaline solution. This is the key to deep cleaning for grease.

Method 1: Salt and Ice

This is a simple trick that doesn't use chemicals. It uses salt and ice to scrub the inside of the glass.

A person swirling ice cubes and coarse salt inside a Chemex to scrub away coffee stains.
  1. Put a bunch of ice in your empty Chemex. Add two tablespoons of coarse salt, a few drops of unscented dish soap, and a little water.
  2. Hold the Chemex and swirl it around fast for a minute or two. The icy, salty mix will scrub the coffee oils off the glass.
  3. This works well for light or medium oil buildup.

Method 2: Baking Soda

This is a bit stronger than salt and ice. Baking soda can scrub away stains and also helps get rid of smells.

  1. Put a teaspoon of baking soda and some unscented soap in the Chemex. Fill it with hot water.
  2. Let it soak for 30 minutes, then scrub it well with your bottle brush. This method can work better than vinegar for hard stains.

Method 3: Professional Coffee Cleaners

This is what you use when your Chemex is really stained. People suggest things like OxiClean, Cafiza, or even denture cleaning tablets.

They all seem different, but they work the same way. When you mix them with hot water, they create hydrogen peroxide to lift stains and a strong degreaser to dissolve coffee oils.

  1. The Method: Add the cleaner to the Chemex and fill with hot water. Let it soak, and the stains should just flake off. For denture tablets, drop one or two in and let it sit overnight.
  2. The Final Wash: This is a strong cleaner. You have to scrub and rinse it many times. Then do a final wash with unscented dish soap to make sure no chemicals are left.

Table 2: At-a-Glance: Chemex Deep Cleaning Methods

Method Active Agent Chemical Type Best For Removing...
Vinegar Soak Acetic Acid Acid White, cloudy mineral stains.
Salt & Ice Salt Abrasive Light brown or yellow stains.
Baking Soda Baking Soda Mild Alkaline / Abrasive Tougher stains and smells.
Cafiza / OxiClean Sodium Percarbonate Strong Alkaline Very dark, set-in stains.

Step 4: Cleaning Your Filter

People sometimes ask about cleaning Chemex filters. They might be talking about reusable filters. Or they might mean how to get paper filters ready for brewing.

A side-by-side comparison of a reusable metal coffee filter and a disposable Chemex paper filter.

Paper filters are only used once. You prepare them, you don't clean them.

How to Clean Reusable Filters

Reusable filters are great for saving money, but you have to clean them well. They can get clogged with tiny coffee grounds and oils.

Should You Wet Paper Filters Before Brewing?

Yes, you absolutely should. This is a very important step for brewing good coffee. Some people say it's to wash away a paper taste, but there are more important reasons.

  1. The main reason is to heat up the brewer. The glass Chemex is big and can cool down your water. Pre-heating it helps keep the water hot enough to brew correctly.
  2. Rinsing also helps the filter stick to the glass walls. This creates a good seal so the filter doesn't move around.
  3. Wetting the filter also helps the water flow through the coffee grounds evenly. This makes sure you get all the good flavor out of the coffee.

Here's how to do it. Put the filter in the Chemex with the 3-layer side facing the spout. Pour hot water over it to wet the whole filter and heat the glass. Then, carefully dump the water out before adding your coffee grounds.

Step 5: How to Prevent Problems

This last step is about two things. First is how to stop stains from building up. Second is how to stop your brew from getting clogged.

How to Stop Buildup

The best way to prevent tough stains is to clean your Chemex daily. Just use soap and water right after you brew.

How to Stop a Clogged Brew

It's very frustrating when your coffee just stops dripping through the filter. This makes the brew take way too long, and your coffee will end up tasting bitter.

A stalled brew usually happens for one of three reasons. Here is how to figure out the problem.

Clogged Brew Fix: The most common cause of a stalled brew is "vapor lock." Always place the 3-layer side of the paper filter against the spout. This creates an air channel, allowing coffee to flow freely into the carafe.
  1. Check the Airflow: The wet paper can sometimes stick to the glass and create a seal. This "vapor lock" stops air from escaping, so the coffee can't flow down.
    • The Fix: This is an easy fix. Always put the 3-layer side of the filter against the spout. This creates an air channel so the coffee can flow freely.
  2. Check the Grind Size: If the airflow is fine but it still clogs, your coffee grounds are too fine. The tiny coffee dust is blocking the filter.
    • The Fix: Use a coarser grind. The Chemex filter is thick and needs a medium-coarse grind, almost like what you'd use for a French press.
  3. Check Your Pouring: If the airflow and grind are right, the problem might be how you pour the water.
    • The Problem: Pouring too fast or swirling the coffee too much can cause problems. It makes all the tiny coffee particles sink to the bottom of the filter where they form a thick layer that blocks the water.
    • The Fix: Pour the water gently and don't swirl it too much. You can also try pouring the water over the back of a spoon to soften the stream.

Helpful Tools for Cleaning

The Chemex itself is simple, but you'll need a few tools to keep it clean.

A flat lay of essential Chemex cleaning tools including a bottle brush, unscented soap, vinegar, and baking soda.

More Cleaning Tips

Tips from Coffee Fans

When you look online, you'll see a few common tips for cleaning a Chemex.

All these tricks work well because they use the same kind of powerful cleaner. They are great at dissolving old coffee oils.

How to Clean the Chemex Ottomatic

The Chemex Ottomatic is an automatic brewer that needs to be descaled, just like a regular coffee machine. If you don't do this, it could void your warranty.

The Chemex Ottomatic automatic pour-over coffee brewer machine.