Thoughts on Cafec Roasting Level Paper Filters
These filters actually available in market for awhile but recently comes into Canada, so I have brought in some and feel very exciting to try them out.
From my understanding, these filters use "crepe" (you can see it as density of the paper surface) on inside and outside of the paper to control the flow rate. Higher crepe (lower density) has better permeability and can let more fines fill into the gap between each crepe, so water flow down with less resistance, result in faster flow rate. On the other hand, lower crepe (higher density) works in the opposite way. You can see the paper density better in below pictures, the upper one is Light roast filter and the lower one is Medium-Dark roast filter.
Higher crepe also means thicker. We can see from the picture below for filter thickness, Medium-Dark roast filter on the right (MDR)>Dark roast filter on the middle (DR)>Light roast filter on the left (LR). I personally like the texture of LR, very soft and silky.
For this test I used Loveramics Smooth Dripper, everything is the same except for filter, 50g water for 20s bloom then single pour to 300g.
LR: Around 2min20s, light body and clean flavour, strong tea-liked finish.
MDR: Around 2min7s, better flavour complexity and intense.
DR: Around 2min13s, mild flavour and thicker body.
My opinion is don't focus too much on the name (light, dark roast), see them as a tool to help you control the flow rate. For example, if you like use fine grind, fast brew and also want a bit body on light roast coffee, you can try MDR instead of LR.
P.S. I like MDR better, for now.