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What are Blackout Blinds?
Blockout Blind? Total Blackout Blind? Cassette Blackout Blind? BlocOut™ Blind?

What is a Blackout Blind?
We get asked for a Blackout Blind, a Blockout Blind, a Total Blackout Blind, a Cassette Blackout Blind, a BlocOut™ Blind , a Blackout Blind with Side Tracks, a Blackout Blind with Side Channels, a Blackout Blind with Side Rails, a Roller Blockout Blind - call it what you like, the purpose is to exclude light.
The first thing to understand is that all "blackout" blinds are made from fabric which light does not come through, however, it will not stop the light at the edges unless you do something extra. This is where side channels or side rails or a fully cassetted option begin to make sense. You can make any type of blind from light proof material, but if there are gaps it will not be blackout. (BlocOut™ is a trademark of Bloc Blinds, an award winning product)

Can I get a 100% Total Blackout Blind?
Yes and No. Effectively, to any rational person, we can achieve Total Blackout with a Fully Cassetted Blackout Roller Blind. However if viewed close up, staring sideways into the side rails, or peering up around the ends of the headrail, you may see a glimmer of light. For that reason we would only claim 99% exclusion of light not 100%. When you exclude virtually all light the tiniest pinprick of light does become super bright and visible.
(you have met the general public I assume, on one occasion in forty years I met that particular gentleman, he peered sideways at the blind from close up and pointed his finger and screamed "I can see light, do you call that Total Blackout" :) )

Will a Blackout Blind make the room warmer/colder ?
Yes. Because you are adding a lightblock (airblock) you will reduce draughts around the window, also if you leave the blind closed in summer you will reduce heatgain - leaving the blind 90% closed in summer with the window open can be the best option for lowering heatgain whilst airing the room. We also have thermal honeycomb blind fabric which as well as being Blackout also traps a blanket of air for additional insulation in both winter and summer.

Can I leave my window open with a blackout blind?
You can, but it may not be a good idea. If you do not have side channels the fabric will catch the wind and the bottom rail will clatter, if you have a fully cassetted option for effective blackout solution then the airflow is restricted and why have the window open. If you want excellent blackout with an open window please consider blackout curtains (Changing Curtains also supply and fit superb blackout lined curtains in any fabric of your choice)

Below I discuss various types of Blackout Blind and how efective they might be, and I also add photographs to try and demonstrate this.

Blackout Roller Blind   A roller blind made with light blocking fabric, but there is lightwash at the edges. If the fabric is fitted into side channels or side rails which are attached to the window frame or wall you eliminate light seepage at the sides. If the roller itself is installed inside a headrail or headbox you eliminate light seepage around the roller at the top. If the bottom edge of the blind drops into a bottom rail you eliminate light at the bottom. If you fit all of these it could be described as a Full Cassette

Click on any of the photos below for more info and a link to a video showing that blind in operation
Cassetted Blackout Roller Blinds North London
Cassetted Blackout Roller Blinds North London
Blackout roller blind with Full Cassette (side rails, bottom rail and headbox) Central London
Blackout roller blind with Full Cassette (side rails, bottom rail and headbox) Central London
Fully Cassetted Blackout Roller Blind fitted behind existing blind East London
Fully Cassetted Blackout Roller Blind fitted behind existing blind East London

     Blackout Honeycomb Blind   A blind made with "Honeycomb" fabric - such as duette, which has two layers with an air gap between for extra sound and heat insulation. This fabric can be light stopping, but there can be gaps at the sides, fitting inside or behind side rails or side channels can help prevent this, but the honeycomb shape at the edges can leave glimmers of light. The headrail at the top leaves very little space for light wash and the bottom rail falls fully to the bottom of the blind drop, so if your sill is straight (HoHoHo?) there will be little light visible there. You dont usually require a full cassette for effective blackout

Honeycomb Blackout Blinds installed London
Honeycomb Blackout Blinds installed
Honeycomb Blackout Blinds installed London demonstrating lightwash
Lightwash at the edges
Honeycomb Blackout Blinds installed London now with side channels fitted for one of the blinds
Side channels fitted for one blind
Honeycomb Blackout Blinds installed London now showing difference side channels make to lightwash
Reduced lightwash from one blind
Honeycomb Blackout Blinds installed London both blinds now have side channels
Side channels now fitted for both blinds
Honeycomb Blackout Blinds installed London, both blinds have side channels and the photo is almost completely dark, there are glimmers of light from near the headrail
This is not a completely blank photo, if you expand it and look closely there is a tiny bit of lightwash


Blackout Roman Blind   A roman blind made with a blackout lining. Because of the way it is made you may get some light coming through where the stitches are holding the pockets in place so the blind can fold. The headrail at the top will exclude most of the light, but the fabric hangs from the front of the headrail and there are always gaps at the sides. If side rails or side channels are fitted this can help, there still may be light at the bottom. Because roman blinds are a softer fabric look it can be preferable to add a pair of dress curtains at the sides, made with blackout lining and hung correctly these can provide a very effective lightblock at the sides

Blackout Roman Blind fitted in North London
Blackout Roman Blind fitted North London
Patio doors in Hertfordshire with blackout roman blinds
Blackout roman blinds for patio doors installed Herts

Blackout roman blind fitted Essex

Blackout Vertical Blind   A vertical blind made with light blocking fabric. This can be a useful option which is inexpensive and can provide elements of privacy during the day depending on how the louvres are rotated. But, this option will never provide Total Blackout because although the louvres can rotate 185 degrees the fabric to fabric overlaps are never light tight, there is always light wash at the top between the louvres and the headrail, at the edges where the louvres are never quite as wide as the headrail, and at the bottom because there is a gap so the louvres are free to rotate and draw. Depending on which way the sun comes up and which direction you rotate the louvres you can reduce the light to an extent. Not a great option if you are seeking true blackout

Blackout Venetian Blind   The slats of a venetian blind are usually lightproof, whether aluminium or wood. But the ladders mean that the slats never close all the way and there is "the pyramid effect" which means that each slat closes a tiny bit less than the one above leaving bigger gaps at the bottom (more noticeable on a long drop blind). Because of reflected light from a white surface you will achieve greater darkness from a dark venetian blind than a white one, but you will never get real blackout  

All photographs on this page were taken by our staff after Changing Curtains created and installed the blinds. All of these photos are copyright.
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