A Primer on Chemex Filtration

Is there a cleaner cup of coffee?

Chemex filters are some of the most unique out there. Paper filters have been produced for a long time in immeasurable quantities, but Chemex filters are sort of like the specialty coffee of paper filters. Here’s a few things about Chemex filters that you might not know.

Thicker Than Other Paper Filters

One of the hallmarks of Chemex coffee is its ability to produce a consistently clean, bright cup of coffee. Well, it turns out that most of the credit for this cleanness can be attributed to the special Chemex filters. They are about 30% heavier than other paper filters, which in turn makes them sturdier and more resilient.

These are almost twice as thick as other paper filters, making them twice as effective at trapping oils, impurities, sediment, and so on. This makes for a very balanced flavor in your coffee cup, as well as helping achieve very consistent results even for novices.

Conversely, these filters are also healthier for us since they trap almost all of the oil found in coffee beans which can -and does- elevate cholesterol levels even in healthy individuals.1 Thank you, Chemex, for keeping us healthier!

Circle or Square: Your Choice

The classic Chemex filters come as pre-folded squares that stick up and out of the Chemex when inserted into the carafe. Unfortunately, this aesthetic is considered ugly by many Chemex users.

Chemex heard its customers loud and clear, and now manufactures circle-shaped filters of the same material and quality as its classic filters, just for us to have a different choice.

Why Chemex Filters?

Chemex has always been about the science. They have continued to make paper filters because they know that their paper is better. This laboratory-grade paper is infinitely better at making coffee, while metal filters provide a different flavor that can mostly be attributed to loose coffee particles, oils, and etc. This means that the difference in flavor is mainly because of the ineffectiveness of metal filters; accident, not virtue is what causes this difference in flavor.

Therefore, Chemex has maintained their stance on paper filters and continue to manufacture their trademarks super thick filters.

Should You Wet the Filter First?

This practice of pre-wetting the filter is rather common among professional coffee experts. Does washing the filter make an actual difference?

Well, it does, and it doesn’t. This practice has become common in other brewing methods that may use mass-produced, no brand paper filters which have a very distinctive smell and flavor. This contamination can cross over to our cup. With the Chemex filters, this isn’t really much of a problem.

If you find the taste of paper highly unpleasant, then go ahead and rinse your paper filter!

Natural or White Paper

Here we come to a question of pure aesthetics. Both kinds of filters have been purified through a series of hot water baths. The only difference is that the white paper filters have been bleached— that’s all. They are exactly the same paper, just different colors. If you’re interested in learning more about the differences between bleached vs natural filters we wrote check our article covering characteristics of both.

With no real difference, it all comes down to what color filter you think looks best.


Most Chemex filters fit all their coffee makers, except for the smallest of them all; the three-cup size (across all models) and their Funnex. For this, they have a special size, called Half Moon.

The Half Moon is identical to the other Chemex filters in composition, and just like the other two filters, it can be found bleached and unbleached.

  1. “’How Coffee Raises Cholesterol.’ ScienceDaily, 15 June 2007.” https://www.sciencedaily.com/releases/2007/06/070614162223.htm ↩︎

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