I bought motorized blackout blinds from Ikea. After installing it I still see lights coming out of the side of the blinds. What can I do it completely block the light from entering in? Please see the picture for reference. enter image description here


Your problem is that light bounces. White looking surfaces reflect a broad spectrum of light, and even black looking surfaces can reflect substantial amounts if smooth/shiny. You can see from the lighting on the frame in your picture that some of the light hitting the inside of the frame is actually reflection off the blackout curtains. To prevent the light from getting through, pretty much your only options are to block it or absorb it the best you can.

You could paint your window in vantablack, the blackest pigment humanity has come up with. This would stop almost all of the bouncing light and give you a very odd looking, possibly overheating windowframe. It's kind of elegant, but probably not the best solution. A more realistic solution would be to come up with a temporary addition for the curtains when you need it to be really black.

Thick black felt is probably a good option that will give you flexibility and easy mounting without permanent surface damage. The porosity combined with the dark color of the material help it absorb light without reflecting much.

If you want to try semipermanent so the blinds still open, I'd try putting a 4-6" wide piece of absorbent material up the center post of the frame on the inside so it overlapped the edges of the blinds, and L shaped flaps on the inside of the frame to the left and right.

Note that complete blackout is extremely difficult to achieve because of the way your eyes adjust to darkness. A tiny percentage of the total illumination available will seem like a fair bit of light once your eyes adjust.

If you want an absolute and elegant solution and you don't mind spending some money, you could look at something like Peka roll shutters or similar external security blinds, but obviously it won't be cheap and would look extremely odd on some external finishes.

  • Something to consider: The entrance to the darkroom I used in high school consisted of a black curtain, a short hallway (~5'), a u-turn, then another short hallway (~5'). The walls of the hallway were painted black. The curtain, black paint, rough cinder block walls and u-turn were more than enough to keep it about 99% black in the darkroom when the lights were blazing in the outside "light" room. (This was the film developing room, so red lights and the tiniest bit of "white" light were acceptable.) +1
    – FreeMan
    Apr 20 '21 at 11:53
  • Oh, and, IIRC (high school was many moons ago), there was nothing special about the black paint - it was just... black paint. It may, frankly, have even been a gloss black for all I remember.
    – FreeMan
    Apr 20 '21 at 11:53

When my grand children were younger and the came to stay at our home , we had the same problem in their bedrooms. Even a little morning light would wake them up early and for most of the day they were, "DIFFICULT" to handle. My solution was to install "horizontal blinds" to cover the windows and over top of them a second set of "vertical" blinds covering the whole window that exceeded the window area by about 12" on both sides plus the top and bottom. You could also add a set of heavy curtains that stop the light

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