Difference between metal, cloth and paper filters?

The three main filter types for filter coffee — paper, metal and cloth — produce distinctly different flavour profiles. Paper retains oils and fines, producing a clear, light, aromatic cup. Metal lets oils and fines through, producing a full-bodied, more textured and slightly cloudy cup. Cloth (flannel or nylon) sits between the two: it retains fines but allows some oils through, producing a round, smooth and clear cup — often described as the softest of the three expressions.

The history of cloth filtering is the oldest of the three. Before Melitta Bentz invented the paper filter in 1908, filter coffee was brewed in cloth socks or bags. The method remains alive in several countries: flannel coffee (nel drip) is a vibrant tradition in Japan, Costa Rica and Thailand, prized for the remarkable softness it brings to the cup.

A quality cloth filter (typically untreated cotton flannel, or fine-mesh nylon) physically retains coarser particles and the most significant fines, but its woven mesh allows oil molecules to circulate. The result is a cup with less turbidity than metal, but more body than paper. Dried-fruit, cacao and honey notes are often better expressed than with paper.

Cloth filter maintenance is the most demanding of the three. After each use it must be rinsed in cold water (not hot, which cooks coffee into the fibres), stored damp and refrigerated, and replaced every 2 to 3 months depending on frequency of use. A poorly maintained cloth filter transfers very unpleasant rancid flavours to the cup — which is why many enthusiasts abandon the method after a few months.

As with metal filters, the diterpene question arises. The cloth filter lets through an intermediate proportion — less than metal, more than paper. For large volumes (full pots several times a day), paper remains the most neutral option in terms of lipids.

The environmental balance is complex. Unbleached paper filters are compostable but their production has a water and energy cost. Metal filters last years but require steel in production. Natural cloth filters are the lowest-tech of the three and have the lowest industrial impact, but require the most water for maintenance. There is no universal answer — it depends on how the user weighs the criteria.

Comparison: paper / metal / cloth filter