Flannel is generally made with either a twill or percale weave. The fabric is then napped to hide the weave. Napping is a finishing technique that gives flannel that signature fluffy, fuzzy feel. Flannel can be napped on just one side, or it can be double-napped, meaning both sides of the fabric are napped, for extra softness. Flannel is also often sheared after napping for a smoother texture.

Lyocell is similar to viscose in that it is a regenerated cellulose fabric, but is made with a more eco-friendly process. TheU.S. Federal Trade Commissiondefines lyocell as rayons “composed of cellulose precipitated from an organic solution in which no substitution of the hydroxyl groups takes place and no chemical intermediates are formed” — essentially meaning it does not use the harmful chemical solvents normal viscoses use. Lyocell production also results in little waste product, but it is still relatively energy intensive.