Why can roller blind fabric become slightly curved on wide blinds?

When manufacturing wider roller blinds, a slight bowing or curved effect may sometimes occur in the fabric. This phenomenon is normal within the industry and is commonly referred to as cupping. The effect becomes more noticeable when the total width of the roller blind exceeds the original roll width of the selected fabric.

Why does this happen?

Many modern roller blind fabrics are considered reversible fabrics, meaning the same side of the fabric can face either inward or outward. To manufacture blinds that are wider than the factory roll width of the fabric, the material sometimes needs to be processed and cut differently compared to standard production.

When the fabric is cut and processed along the roll direction of the original fabric roll, the natural tension within the material may change. As a result, the outer edges of the fabric can react slightly differently compared to the center section, which may create a subtle bowing or cupping effect near the bottom bar of the blind.

The effect may vary depending on:

• The structure and coating of the fabric
• The width and height of the roller blind
• Light exposure and temperature changes
• Whether the fabric is blackout or transparent
• How much of the blind is extended

Most common on wide blinds

The phenomenon is typically more visible on:

• Very wide roller blinds
• Thin or soft fabrics
• Blackout fabrics
• Blinds where the final width exceeds the original factory fabric width

Is this considered a defect?

No. A certain degree of bowing or cupping is regarded as a normal fabric characteristic within the roller blind industry and falls within accepted European tolerance standards for roller blinds.

According to industry standards, a certain deviation is permitted depending on the width of the fabric.

This does normally not affect the functionality of the roller blind and is primarily a visual effect that may become visible under certain lighting conditions.

Important information

When ordering very wide roller blinds, we always try to select the most suitable fabric and production method in order to minimize the risk of cupping. However, the phenomenon cannot always be completely eliminated because it is related to the natural characteristics of the material itself.

This applies especially to wide blinds where the finished blind width exceeds the original width of the fabric roll.