From the paper linked in the post: > [...] boiled coffee was poured through a two-layer polyester/acrylic sock (an occasional household recommendation as poten

From the paper linked in the post: > [...] boiled coffee was poured through a two-layer polyester/acrylic sock (an occasional household recommendation as potential substitution for a paper filter) No kidding. I thought the sock was just a cute icon they used for the graphical abstract.