coffee filter : key properties

( from instagram post 2025.3.8 )

In addition to filtration speed, there are other properties that affect the performance of filter paper:

1. Thickness and surface texture.

They are associated with the "total filtration area" thus the "loading capacity". A thick, heavily creped filter offers more surface areas to trap fine particles, pores are less clogged resulting in steadier liquid flow.

My favorite hario v60 tabless is the one that is heavily creped. Although not the fastest filter in the market, it rarely clogs and never disappoints me for its consistent brew times.

2. Average pore size.

Unlike metal filters, paper is made of natural wood pulp and contains pores in varying shapes and sizes. Therefore, "average pore size" is used to classify the particle retention (in microns) of a filter.

The larger the pores, the faster the liquid flows. Large pores also allow very small fines to pass through that can detriment cup clarity, presenting muddy and bitter flavors. On the contrary, small pores can filter out higher amount of fines but also require more filtration areas to prevent clogging.

The first video shows a cup containing some very fine undissolved solids. It was brewed using a relatively high-speed, smooth filter. Although the acidity was decent, it was slightly masked by a smokey, bitter undertone. In comparison, the cup in the last video looked crystal clear and was brewed using a med-slow, creped filter. I had to make up the brew time with a coarser grind resulting in softer acidity, but had better clarity and a smoother finish.

In the end, it all comes down to our taste preference.