One-of-a-kind Coffee Filter

Do you randomly watch Coffee Championship videos? I do.

I was recently watching 2025 World Brewers Cup videos and came across something very interesting.

It is a filter, used in making a pour over coffee, that doesn't let plain water pass through initially, until the first parts of the coffee is extracted.

I know this is cool but before we look into why and how that is possible, let's talk about why filters in coffee brewing.

Filters are what separate coffee from water. So they do seem to play a crucial role.

Types of filters

Broadly, there are 3 types of filters - paper, metal and cloth.

Paper filters are the most used. For all types of major types of coffee brewing like pour overs, Aeropress, chemex etc. They tend to filter very well, effectively trapping oils and fine particles resulting in clean cup with enhanced brightness and acidity. The best part about these is that there is no sediments in the cup.

Metal filters have larger pores than the paper ones, allowing oils and fines to pass to the cup. It results in much fuller body and a good mouth feel.

This is not always not desirable. There were a lot of Aeropress Championships which were won with a metal filter.

Cloth ones, although I haven't used them yet, seem to be a middle ground between paper and metal. It has a faster flow rate than paper which means higher extraction.

Flow rate is the speed with which water passes through the coffee bed and falls into the cup. Matters only in percolation type brews like pour overs, or the unverted aeropress.

Now, in paper filters, there are yet a few types. Not all paper filters are the same. You can choose ones based on the flow rate or their ability catch the micro-fines from going into our cups. For example, if brewing with dark roasts, Cafec T-90 helps you not over extract with a faster flow rate.

This difference is achieved based on how thick and porous the papers are made. They can choose to have different textures inside and outside.

Coming to the one-of-a-kind one

Water is in the filter but doesn't drip. Source

This one is so new I could not find any material online.

It is essentially a hydrophobic filter. Meaning that it repells water. So initial till it is only water and nothing else, nothing passes. This results in an immersion style bloom for some time. My guess is that it improves the acidity and sweetness.

Slowly when the coffee starts to extract, chemicals in coffee react with the filter and let it pass and it becomes a normal filer.

All of this is fascinating to me. I hope I passed on some of it to you now as well.

As usual, let me leave you with some links so that you can explore further.

More Links to explore

The competition video 👇🏼

That’s all I have. Have a caffeinated weekend.

See you.

Keep on brewing!