plain curtains are not always good for blackout purposes unless they are made with the right material. Just because a curtain is plain does not mean it can block light. Plain curtains are simple in design, but the fabric they are made of is what really matters for blocking light.

If plain curtains are made of thin or light fabric, sunlight can easily pass through. These are better for decoration or light filtering, not for complete darkness. To make plain curtains work for blackout use, they should be made from thick, tightly-woven fabric like polyester or velvet. Some plain curtains come with an extra blackout lining on the back. These are much better for blocking light and keeping your room dark.

Many people like plain curtains because they are simple, match any room style, and can be made to fit many needs. If you want both a simple look and full light control, choose plain curtains that are labeled as “blackout” or come with a lining.

So, in short: plain curtains can be good for blackout use, but only if they are made with thick or blackout fabric. Always check the curtain label or ask the seller before you buy.