What is room darkening vs 100% blackout?
While sometimes used interchangeably to mean the same thing, blackout shades are not the same as room-darkening shades. Room-darkening shades reduce approximately 95-99 percent of light that enters a room. On the other hand, blackout styles can eliminate brightness by up to 100 percent in some cases.
Like blackout curtains, room darkening curtains are designed to block light, but they aren't exactly the same. Room darkening curtains are made with a fabric liner that's not quite as thick as the one used with blackout curtains and which allows a small amount of light through.
At IKEA, there is a difference between blackout curtains and darkening curtains. Blackout curtains block nearly all light. Darkening curtains let a little amount of light pass through.
To block out light 100%. This means, no amount of light passes through the fabric. Hence, the name 'blackout'. Because of the thick fabric, they also come with an added bonus; the ability to muffle sound.
When considering whether to purchase light filtering or room darkening blinds, many homeowners ask, “Can you see through light filtering blinds at night?” The answer is, thankfully, no.
CONS: -May take up more space: Blackout curtains are hung from a curtain rod, so they may take up more space than blackout blinds. -Can be difficult to clean: Blackout curtains can be more difficult to clean than blackout blinds because they are typically made of a thicker, heavier material.
If having a private, low-lit room is important to you, then absolutely, they're worth it! Room darkening shades do exactly what they say – they darken a room. Because of their vinyl material, they block up to 95% of incoming light.
The two types of shades that are best for blackout are cellular and roller shades. Cellular shades are made of one piece of fabric or material so they have a flat, thick surface to provide total blackout. Roller shades come with a pleated or honeycomb construction that is thick enough to keep a room dark.
Roller blinds are perfect for all rooms in the home. However, they are particularly great for bedrooms, given how easy they are to motorise and fit with a blackout lining. A blackout roller blind is an easy way to cast your room into total darkness.
Room darkening curtains are a type of window treatment that is designed to block out a significant amount of light without being 100% blackout. Most “blackout” curtains are simply room darkening curtains without any certifications toward their blackout fabric capability.
What is the difference between blackout and Dimout?
Blackout fabrics 'block' 100% of light from being transmitted from one side to the other. This is achieved by applying one or a number of coatings to the reverse of the fabric which 'blocks' light. Dimout fabrics Significantly reduce the degree of light transmission from one side to the other.
In short, black out is a verb and blackout is a noun. Use each spelling accordingly in your writing. Notice that a hyphen is never to be used. The single word spelling is appropriate when using the term as an adjective.

The fabric used in room darkening blinds will have fewer layers than blackout fabrics. The thinner fabric allows some light to pass through but still blocks 95% of light.