Washing Curtains by Fabric: Cotton, Linen, Polyester and Blackout

Curtains fail in the wash more often than they fail on the rod. Almost every ruined panel died of the same three things: hot water, a tumble dryer, or the wrong assumption about what the fabric was. The care label is the ceiling — the notes below explain what the labels are protecting.

Why the first wash is the risky one

Untreated cotton and linen curtains commonly shrink 3–5% on the first wash, a figure consistent across manufacturer care guidance and published textile references. Heat and agitation are the levers: cold water, a gentle cycle and no dryer keep the movement small. Pre-shrunk or sanforized fabric has had the tension relaxed before it reaches you, so the movement is smaller — but not zero.

Cotton and linen

Cold to 30 °C on a gentle cycle, one or two panels per load, mild detergent. Remove hooks and rings first — metal marks fabric and snags it. For linen, expect creases; linen hangs out most of them if it goes back on the rod damp. Iron damp, on the wrong side, at the linen setting. Where the label says dry clean, believe it: linen drapery faces are often sized, and washing undoes the finish.

Polyester

The easiest panel in the room. Cold to 30 °C gentle, minimal shrinkage, wrinkles drop out on the rod. Iron low if at all; high heat can glaze polyester. Skip fabric softener — it coats the fibre and dulls the finish.

Blackout: check the back before anything else

The fabric on the front tells you nothing. Turn the panel over:

• A smooth, shiny or rubbery back is a coating — foam, acrylic or rubber — applied over the fabric. That coating is what blocks the light, and heat, agitation and solvents all attack it. Spot clean it. Hand wash cold if it must be washed. Never tumble dry, never iron the coated side: heat cracks and peels the layer, and the damage is permanent.
• A back that looks like fabric — the same weave as the front, or a lighter liner sewn in — is a woven or triple-weave blackout. Those wash cold on a gentle cycle like any other polyester panel.

If the label is gone, test a hidden corner: a drop of cold water and mild detergent, left a few minutes, then blotted. Coating that transfers to your fingers will not survive a wash.

Fabric	Water	First-wash shrinkage	Dryer
Cotton, untreated	Cold–30 °C gentle	3–5%	No
Linen	Cold–30 °C gentle	3–5%	No
Polyester	Cold–30 °C gentle	Minimal	Low, only if the label allows
Blackout, coated	Spot clean; hand wash cold	—	Never
Blackout, woven	Cold–30 °C gentle	Minimal	No

Rehang damp, always

The final step is the one most often skipped: put the panels back on the rod while still damp. Gravity pulls the wrinkles out as the fabric dries, and the panel finishes in the shape it hangs in. Do not fold a damp coated panel against itself — the coating sticks to itself and peels apart when separated. Between washes, a vacuum with a brush attachment every couple of months does most of the work — more often in kitchens. On windows that condense, the EPA and CDC 24-to-48-hour drying rule applies to the hem as much as to a flooded floor: a hem that stays damp grows mildew. If the panels come back shorter than expected, the drop and ceiling-height arithmetic tells you where the hem should now sit, and what the lining layers contribute explains which layer is worth protecting.