Blackout Blinds

Firstly what are blackout roller blinds?

It is probably simplest to say that blackout blinds are designed not to allow any visible light to penetrate through a window into a room. The best blackout roller blinds on the market in the UK are systems that have been designed to exclude the maximum amount of visible light as practically possible and are those systems that come closest to blocking 100% of visible light. However no manufacturer will claim to exclude 100% of visible light as the fact that the fabric must be free to move to open and close means there will always remain a theoretical possibility that light may be able to transfer around the edge of the fabric or the internal sections of the mechanism. In reality any good blackout roller blind system should appear to exclude 100% of visible light to the naked eye when closed.

Before going into more detail about made to measure blackout blinds we should mention what does not qualify as a blackout blind, though is often called such. When closed, true blackout window blinds are designed not to allow any visible light to be transmitted through the fabric, not to allow any light to escape around the sides or bottom of the fabric and not to allow any light to escape around the roller and mechanism at the top. Most products that are sold today that are termed blackout blinds are simply roller blinds made with a blackout fabric. This means that when closed no visible light is allowed to be transmitted through the fabric but will however allow light to escape around the sides and the bottom of the fabric, and will also allow some light to escape around the roller and mechanism at the top. These types of window coverings do achieve good levels of room darkening, but this also means that the effect of the light penetrating around the edges of the fabric is greatly exaggerated. A blind that allows light penetration in this way like this should correctly be termed 'dim out'.

When should I use a blackout roller blind? When will a dim out blind suffice? What other blind options are available online? What else could I do?

The decision to buy a blackout blind is therefore really based on how important it is to eliminate the light seepage around the edges of the fabric as described above. This should be considered along with the additional costs involved, as well as the aesthetics of having the cassette and side and bottom channel components fixed around the windows. Made to measure blackout roller blinds are normally used in rooms which, because of the requirements of light sensitive activities which will be undertaken in them, must be able to be fully darkened. Therefore black out roller blinds are most commonly used in more commercial environments in the UK including laboratories, hospitals, projection rooms and dark rooms.

If you are considering purchasing a blackout window blind then also consider using a simple roller blind mechanism in a cassette housing with side guide channels. The cassette and channels will reduce the amount of penetrating light considerably, which may be suitable for the children's bedroom or as a roller blind for the bathroom, though the light reduction will be less effective than a dedicated system. It is also worth considering installing a simple blind across the full window opening rather than installing it in the window reveal. With a sufficient overlap at the edges of the window opening, again the light penetration will be considerably reduced.

Another cost effective option to consider is one of the new and innovative products that are on the market to provide temporary and in some cases portable solutions. These products usually involve a film or cloth that is fixed either directly to the glass or to the window frame by adhesive, suction or Velcro. These products if fitted correctly can provide excellent levels of room darkening at a relatively low cost.

Finally, it is stating the obvious, but if you are considering a roller blackout blind to create a room with good darkening levels for some activity , then also consider moving the activity to a room which has no windows or one that has external security shutters that can provide sufficient light control. If the black out roller blind could be permanently in the closed position then also consider blocking up the window opening itself.

How do blackout roller blinds work? How do they differ from dim out blinds?

Blackout systems usually consist of the following additional parts to a simple roller blind made with a blackout fabric – cassette head box, heavy duty bottom bar, side channels and bottom channel. The head box cassette is fixed directly to the wall and stops the light escaping around the roller and mechanism. The side channels house a smaller channel for the fabric to pass through which is usually lined with brushes to seal the fabric to prevent light from escaping. A similar brush strip is fitted to the bottom bar to seal against the bottom channel, or against a window board or the wall surface if no bottom channel is used. On the best systems the side channels also include a fabric tensioning and retention system which prevent the fabric from leaving the side channels when the fabric is put under load due to impact or a change in air pressure which can be caused by wind or vacuum. These systems usually involve buttons or a zip being attached to the vertical side edges of the fabric which are too large to pass through a specially flange shaped channel housing. The channel housing is then sprung or tensioned by means of foam or brush strips which push the channel outwards causing the buttons or zips to be pulled to keep the fabric tort. As well as maximising light retention the guidance and tension systems also make sure that the fabric stays in line when the blind is retracted as any dislodged fabric in a roller blind with side channels can be problematic and can cause jamming of the mechanism.

What options and accessories are available?

Roller blackout blinds can normally be installed equally successfully either in the window reveal or across the window opening. Specialist systems are available with opening mechanism options which include tensioned spring, tape operation, chain operation, winder operation as well as electrical operation controlled by switch, remote control or automatic sensor. These systems can also be installed side by side with a common operating mechanism to cover multiple windows and are usually available with many colour and style options for the fabric and a small number of standard colours for the cassette, side channel and bottom bar components.

Are there any other benefits?

As well as being the best system to control light penetration these systems are also the best at providing protection against solar radiation, to retain heat within a room and to reduce levels noise pollution from outside of a building.