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BLINDSPEC

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Blackout & Room Darkening

The category’s most misunderstood promise, told straight: "blackout" describes the fabric, not the installed result. Mount a blackout shade inside the frame and daylight still rings the edges through the deduction gap — so a genuinely dark room takes more than a fabric label. This hub is the honest playbook for real darkness: outside mounts with generous overlap, side channels that seal the light gap, dual-shade setups, and the difference between blackout and room-darkening when "comfortably dim" is all you actually need. If a bedroom, nursery, or media room is the job, the mount matters as much as the weave.

Where to start

Comparisons

Glossary terms

Blackout Fabric
Fabric that passes no light — but the installed shade still leaks at the edges.
Room-Darkening Fabric
Cuts most light but not all — the honest choice when you just want dimmer.
Side Channels / Light Blockers
Tracks along the window edges that seal the light gap a shade leaves.
Light Gap
The daylight leak around an inside-mounted shade — physics, not a defect.
Outside Mount
Mounted on the wall or trim above the opening — forgiving and darker.
Lining (Blackout / Privacy / Interlining)
The backing fabric that sets a shade’s light control and body.
Routeless / Privacy Slats
Slats without lift-cord holes — better closed privacy and light control.

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