Can you reuse Chemex filters? We have the answer!

The Chemex coffee maker is one of the great classic pour-over coffee makers. You can make fantastic coffee with one, and as a bonus, it looks great on your countertop. 

But, the Chemex coffee maker uses a proprietary bonded paper filter. Which is quite expensive compared to competitors. So you might be tempted to wonder whether reusing the Chemex bonded paper filters is possible. Or maybe your reasons for wishing to reuse coffee filters aren’t driven by money. Single-use paper filters might seem wasteful from an environmental standpoint too.

So, can you reuse Chemex filter? Reusing the proprietary Chemex bonded paper filters is NOT recommended. They were made for brewing a single batch of coffee in your Chemex coffee maker. If you wish to use a coffee filter more than once, you’ll need to look into a coffee filter specifically designed to be reusable. There are alternatives that work just as well as paper filters.

In the process or researching the reusability of the Chemex paper filter, I found a lot of interesting information. If you would like to know more about reusing coffee filters or Chemex filters, please consider reading the rest of the article.

Chemex paper filter

What is a Chemex filter?

The coffee filters made by Chemex are not your typical paper coffee filters. They are made of thick paper (20%-30% thicker than on average). This ensures that bitter elements in ground coffee, oily substances, and the finest of impurities stay in the filter and out of your cup. Also, unlike regular paper coffee filters, the Chemex bonded filters are folded instead of pressed together with a seam.

The filters from Chemex are folded in such a way that when opened, you have one side with three layers of paper, and one side with one layer of paper. The thicker side should be placed over the sprout. The three layers of paper prevent the filter from collapsing into the sprout when it gets wet. A collapsed filter blocks the sprout and prevents you from pouring your freshly brewed coffee into your favorite mug. 

The Chemex filter is intended for single use. You brew, and you toss. That’s the deal. 

The Chemex filters come in three different versions for the ‘regular’ Chemex sizes (6-cup, 8-cup, 10-cup) and two for the 3-cup Chemex and the Funnex. The main difference between all versions is that they are either white or brown. This means that they are either put through an oxidizing cleansing bath (white filter) or just through a hot water bath (brown filter). The material of which they are made is the same. Additionally, the filter line-up for the regular Chemex models also has a version where the top has been cut to unfold into a circle. This is purely for aesthetic purposes (see pictures).

In the gallery below an overview of all different Chemex filters:

Which one to choose is purely a matter of personal preference. Every one of the functions in precisely the same way. Some people like the oxidizing process for their filters, some people prefer just to have the water baths. The former is said to clear away some of the paper taste. The production process of the latter puts less strain on the environment. 

And for the difference in shape: some people prefer to have the circle filter paper because it sits nicer in the top part of the Chemex. Others like to have the points sticking from the top for the easy removal of a used filter.

What are Chemex filters made of?

As said, Chemex filters are made from very thick paper. In fact, according to Chemex:

"The paper filters are based on laboratory-grade paper and designed specifically to filter out impurities, all unhealthy and bitter elements from the coffee."

Chemex FAQ's

So it isn’t ‘just’ thick paper. Chemex put a lot of thought and research into it. You might even say that the filter contributes as much to the taste of the coffee you get from a Chemex coffee maker as the design of the device itself. This is what Chemex has to say about this:

"By using Chemex paper filters, one is able to brew coffee as strong as they like, without acidity and bitterness."

Chemex FAQ's

Why are Chemex filters so expensive?

Chemex filters are more expensive than regular filters (like Melitta). But, in my opinion, there are good reasons for this difference in price. A Chemex filter has a lot more material than a conventional paper filter. The material is thicker, and it is folded in such a way that multiple layers form. That means the Chemex filters also have more material than a conventional filter. More of a thicker material means higher costs. 

Let’s face it. A Chemex filter probably has a higher production cost than a more conventional paper filter. Also, the Chemex coffee maker is a specialty coffee maker. One doesn’t but a Chemex to make cheap coffee. You buy a Chemex to make the best coffee. And the best usually comes at a premium.

Can I reuse a Chemex filter?

So, reusing Chemex filters is not recommended. But why? Well, when you brew coffee, the Chemex filter will clog with tiny particles from the ground coffee. These are tiny pieces of coffee bean, oils, and other impurities. 

When you would just throw out the used ground coffee, give the filter a quick rinse, and put in new coffee for a second batch, the filter would still be clogged with gunk. The coffee will run through the filter MUCH slower. This means your coffee will quickly over-extract. And over-extracted coffee is no good, believe me.

And, although the filters are really sturdy and thick, they aren’t made to be rinsed out. You could probably get away with once, but washing them out multiple times would undoubtedly make them rip.

Are there any good reusable alternatives to Chemex filters?

The short answer to that is: yes and no. But that doesn’t help.

The long answer: when it comes to reusable coffee filters, there are two options: those made of a soft material and metal coffee filters. 

The CoffeeSock reusable filter for Chemex

The soft material reusable filters a made of some sort of fabric. There are some good nylon reusable filters, but in my book, there is only one option. The CoffeeSock filter. The CoffeeSock is made from organic cotton. It is designed to be used with the 6-cup, 8-cup, 10-cup, or 13-cup Chemex, but people have also had great success with it in their 3-cup Chemex. The CoffeeSock is incredibly easy to use. After brewing, you dump the coffee grounds (use the in your garden, they work great as fertilizer!), rinse the CoffeeSock, and leave it to dry thoroughly. My advice would be to buy two. It takes a while for the CoffeeSock to dry, and they are best used when they have completely dried. 

Whenever you feel your CoffeeSock needs extra cleaning, you boil it for a couple of minutes. The coffee will stain the CoffeeSock immediately and permanently, but this doesn’t impact the flavor of your coffee. In fact, cotton imparts no flavor at all on your coffee. Unlike paper filters. This is because cotton is 90% cellulose, which is tasteless and odorless. Paper (or wood, actually), on the other hand, is 40% to 50% cellulose. 

Personally, I want the products I buy to be as sustainable as possible in any way. So besides the environmental benefits of a reusable coffee filter, I am also thrilled the CoffeeSock is made in the USA (in Austin, Texas, to be precise). 

Metal reusable filters for Chemex

Metal reusable filters are made from a fine mesh metal. Usually stainless steel, but there are versions of gold plated titanium out there. The most essential characteristic of metal reusable coffee filters is that they cannot absorb as much of the oils and impurities as a paper or cotton filter. 

This isn’t necessarily a bad thing. People who like this say the coffee is more full-bodied and rich, people who don’t say it tastes ‘muddy.’ In any case, a metal mesh coffee filter cannot produce a crisp and clean cup of coffee. The paper and cotton filter absorbs much of the oils and impurities, which lead to a cleaner cup devoid of acidity and bitterness.

Honestly, I think Chemex coffee made with a metal filter tastes more like French Press coffee. For me, the CoffeeSock is the best way to make ‘real’ Chemex coffee and still be able to reuse the filter.

Are reusable filters better than the original paper Chemex filter?

Whether they are better is a matter of personal opinion. 

If you care about the environment, reusable filters obviously put less strain on the environment. 

If your motivation to consider a reusable filter is economical, then: yes, a reusable filter is cheaper in the long run. A CoffeeSock, for instance, only costs a little bit more than 1 pack of original Chemex filters (100 filters). 

If you want to make Chemex coffee that is authentic and use it the way the inventor meant the Chemex to be used: the original paper filters are what you should use. 

Are Chemex paper filters better than steel filters?

We have already figured out that metal filters absorb less (practically none) oils and less of the fines in the ground coffee. But in what way does this impact the flavor of the coffee?

This is what Chemex has to say about this:

"The paper filters are based on laboratory-grade paper and explicitly designed to filter out impurities, all unhealthy and bitter elements from the coffee. By using Chemex paper filters, one is able to brew coffee as strong as they like, without acidity and bitterness. It is a misconception that metal filters provide a "stronger" cup of coffee, when in fact it the coffee produced simply has leftover flavor of the oils and sediments that actually detract from experiencing the full flavor of the beans."

Chemex FAQ's

A bit more by Chemex on the differences in taste between metal filters and paper filters:

"By using Chemex double-bonded filter papers, one will be able to brew the perfect most pure cup of coffee every time. Once all of the impurities, oils, bitter elements have been filtered out, the clean, full flavor of the beans will shine through. When using a metal filter, all of those undesirable elements are left in the brewed coffee."

Chemex FAQ's

Is using paper filters healthier?

There seem to be some health benefits. I am not a doctor or nutrition expert by any means, so let me quote Chemex again:

"There are quite a few proven health benefits when using Chemex filters. Coffee drinkers concerned about cholesterol weren't happy about some early study results showing that coffee seems to increase cholesterol levels and "bad" LDL cholesterol levels in particular. But upon closer inspection, the bad news turned out to be not so bad, because the cholesterol-raising effect seems to be limited to coffee that hasn't been filtered, which includes Turkish coffee, coffee brewed in a French press, and the boiled coffee consumed in Scandinavia.
Harvard Study

The cholesterol-raising ingredients in coffee are oily substances called diterpenes, and the two main types in coffee are cafestol (pronounced CAF-es-tol) and kahweol (pronounced KAH-we-awl). They are present either as oily droplets or in the grounds floating in the coffee. But a paper filter traps most of the cafestol and kahweol, so coffee that's been filtered probably has little, if any, effect on cholesterol levels.
Harvard Study

Our paper filters are based on laboratory grade filter paper, double-bonded thickness to filter out impurities and unhealthy oils, acidity, bitterness, fats and sediments."

Chemex FAQ's

Bonus: How 'regular' coffee filters are made

Unfortunately, Chemex hasn’t shown us how their proprietary coffee filters are made. I don’t think it’s a big secret but haven’t made a video about it (hint!). For those of you who are interested, an old episode of the tv-show ‘How it’s Made’ features the production process of the oldest paper coffee filter manufacturer in the world: Melitta.

Need help brewing the best possible coffee with your Chemex? Check out our Chemex brew guide!

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