Sibarist B3 FLAT vs April Flat Bottom Paper

Fits

Flat basket

Flow

Medium · Manufacturer-stated

Material

Paper

Reuse

Single-use

Availability

Specialty only

How it brews

The B3 grade of Sibarist's abaca flat-bottom paper (associated with Matt Winton's flat-bed method), in S and M. Unlike the FAST papers, B3 is a lower-porosity sheet Sibarist rates as medium flow, trading some drainage speed for more body and retention across the flat bed. That medium class is the maker's own framing, not independently measured. It fits the flat-basket seat and interchanges with other flat papers of that fit; a pre-brew rinse is common.

Fits

Flat basket, Kalita Wave 155, Kalita Wave 185

Flow

Fast · Manufacturer-stated

Material

Paper · Cellulose

Reuse

Single-use

Availability

Specialty only

How it brews

The Copenhagen roastery's own flat-bottom paper, sold Small (≈Kalita 155 / Origami S) and Large (size 175, for the April plastic brewer). It's cut to sit deep with a wide base and is marketed as flowing faster than conventional flat papers — that speed claim is April's, kept as a class rather than a number here. One honest ambiguity: older retailer copy described April filters as using Sibarist's abaca FAST technology, while the current listing says virgin wood pulp (cellulose); we record cellulose per the direct listing but don't treat abaca as confirmed. It drops into a Kalita Wave 155/185 seat, so it interchanges with those papers.