Lining is not optional

Unlined curtains look wonderful in photographs and disappoint in rooms. Without a second layer the face fabric carries every job at once: falling well, blocking light, insulating the window and surviving sunlight. It cannot do all four.

A cotton sateen lining takes the ultraviolet hit so the face fabric does not fade along the leading edge. Interlining — a soft flannel layer between the two — is what gives a curtain the weight that makes it fall in those slow, sculptural folds you see in good hotels.

There is a thermal argument too. A lined and interlined curtain across a single-glazed sash window measurably slows heat loss overnight. Clients notice it first in their heating bill and second in the quiet.

It roughly doubles the making time, which is why unlined quotes look cheaper. Over the life of the curtain it is the least expensive decision on the estimate.