Light control and privacy

Light control runs along a spectrum, from a sheer that keeps the view to a blackout that takes the room dark. Naming where a window needs to sit on that spectrum is the first decision, because it drives the fabric more than anything else.

The spectrum

Light filtering

A filtering fabric softens the light and cuts glare while keeping the room bright and, on a sheer, keeping some of the view. It gives daytime privacy without going dark. It is the most common choice for living spaces.

Room darkening

A room-darkening fabric blocks most of the light but not all of it: a little still passes through the weave and around the edges. It suits a bedroom or media room that wants to be dim rather than fully dark.

Blackout

A blackout fabric stops light through the material itself. To get a genuinely dark room you also have to deal with the gaps at the edges, which is what side channels, a cassette, or an outside mount are for. The fabric alone is only half of a blackout.

Openness factor

Screen and solar fabrics carry an openness factor, the percentage of the weave that is open. A lower number, around 1 to 3 percent, means more privacy and glare control and less view. A higher number, 5 percent and up, keeps more of the view and lets more light through. There is no right answer, only the trade you want between view and privacy.

Privacy changes from day to night

A sheer or filtering fabric that is private in daylight can become see-through after dark, once the lights are on inside and it is darker outside. If evening privacy matters, that is the argument for a room-darkening fabric, or for a second layer.

How each product gets there

On a roller shade the light control is the fabric you pick, filtering through to blackout. A cellular shade is offered in filtering and room-darkening cells and can layer both on one headrail. Horizontal blinds and shutters control light by tilting the slats or louvres, closing toward the room or the glass to change the view. Drapery adds evening darkness and softening over a daytime shade.

Layering

When one window needs both, the usual answer is two treatments: a filtering shade that does the daytime work, and drapery or a room-darkening shade behind it for the evening. Each does one job well rather than one doing both badly.

The reliable way to judge a fabric is to see it on the window. Order a sample in the openness and colour you are weighing up.