Filters are part of the recipe
A filter separates grounds from the drink. Its material, shape and fit in the equipment affect the process. Changing paper can therefore matter even when the bean and water quantity stay the same. A poorly seated filter or blocked air passage can also alter the flow.
Start with the filter specified by the equipment manufacturer. CHEMEX, for example, explicitly describes its system together with its matching paper filters. Other inserts may need their own recipes. An accessory that somehow fits is not automatically an equivalent technical solution.
Paper in everyday use
Paper is easy to remove after use and retains many fine particles. The cup often tastes cleaner than with a more permeable metal filter. Whether to rinse the filter first also depends on the method and paper; it often helps to seat it neatly and preheat the vessel. Discard the rinse water before brewing.
Check the correct size and folding. A torn or folded-over edge can let coffee bypass the filter. When comparing paper brands, keep the rest of the setup as consistent as possible. A change in drawdown time is initially an observation, not proof of better or worse quality.
Metal and cloth
A reusable metal filter can let more fine particles into the cup and create a different mouthfeel. This can feel pleasantly full, but needs to suit your preference. Clean it thoroughly according to the instructions so residue does not affect the flavour of the next portion.
Cloth filters have their own care requirements. They need proper cleaning and storage after use. If that routine feels too demanding, another material may be a better everyday choice. Reusable does not automatically mean easy to care for.
A fair comparison of materials
Brew two small servings with the same beans. Record filter material and shape, dose, water quantity and brew time. Taste at a similar temperature and pay attention to clarity, mouthfeel and sediment. If you also compare different brewers, record that too: a difference then cannot be attributed to the material alone. Adjust each recipe separately afterwards if necessary.
You do not necessarily need a winner. Perhaps you like paper in the morning and a fuller mouthfeel at weekends. Your personal purpose is a better basis for a decision than the idea that only one material can produce real coffee.
Sustainability without hasty conclusions
Disposables create waste; reusables need cleaning and frequent use. An honest assessment considers material, lifespan and care. An unused permanent filter in a cupboard saves little. Choose a routine you will actually maintain long term.
Dispose of filters and packaging according to local rules and material labels. Coatings, additives or composite materials may change their classification. Brown colouring alone does not reliably tell you where something belongs.