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I have an IKEA window roller blind similar to this one. The material is 100% plastic.

It is however dark blue, so it absorbs a lot of sunlight and so it warms up the apartment.

I was thinking of buying some silver paint spray and simply painting it over so that it reflects the sunlight.

Would this work? Or would the paint simply start sticking to itself when it's rolled up (every day), or fall off?

What kind of paint spray would you buy?

Much appreciated your time reading!

window covered with a blue roller blind, with sunlight shining through the panes and the blind

Nelson
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bud.dugong
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  • If you really want to stop the heat coming into the room, then fit a shade outside that stops the sunlight hitting the window. Nature does a good system - called a tree. – Solar Mike Jul 11 '23 at 08:29
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    @ Solar Mike, That window look like it's at least on the 2nd floor if not higher. A tree may take a pretty long time to grow and give shade. – RMDman Jul 11 '23 at 12:16
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    Are you trying to create a _blackout curtain_ that completely blocks the external light or do you still want light to filter through, just without the heat? You might want to use to search for [`solar control film`](https://en.wikipedia.org/wiki/Window_insulation_film#Solar_control_film) for products that adhere to the window and reduce heat, glare and UV. – HABO Jul 11 '23 at 13:57
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    if you really want to go cheap DIY, just tape a bunch of aluminum foil to it. – rtaft Jul 11 '23 at 19:31
  • It appears that 20% of that window is not covered. You should check and make sure that's not the chief issue. Aside from that, spray paint is a terrible idea. There's a good reason why white blinds are a wildly popular color choice... – MonkeyZeus Jul 11 '23 at 20:04
  • Buy a replacement blind in the colour you want, and store this blue one for winter when heat retention is desirable. Swap them twice a year. – Criggie Jul 12 '23 at 00:19
  • Thank you for everyone for the insightful and creative solutions! – bud.dugong Jul 17 '23 at 11:29

2 Answers2

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As your objective is to reflect the light, rather than explicitly paint the shade (more impractical), consider the following.

One can purchase silver reflective mylar sheet from various sources (Amazon) at various prices. A 4 foot x 50 foot roll is approximately US$30 with some variation therein. Even an "emergency blanket" made of mylar would serve, although removing the wrinkles may be problematic.

The sheet (or blanket) could be attached on the inside of the roll up using adhesive tape. Mylar is quite thin and would have little impact on the roll thickness.

Note that such an implementation would reflect the sunlight back toward the glass and is likely to heat the air between the shade and the glass. Convection heating will result. It may be less than that experienced by the bare shade, however.

One can apply self-adhesive reflective window film to accomplish useful reflection, but as this is an apartment, such semi-permanent modifications are often discouraged.

Mylar sheeting

Amazon listed item is source of image, currently out of stock but representative of other similar products suitable for this application.

fred_dot_u
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  • This is prob the best solution, aside from also getting blackout shades. There's commercially available products out there exactly for what OP is trying to do: reduce sun glare heat. One brand I've seen in the US is called "Gila" and they have "heat control" window film, that works kinda like automotive window tint, reflects heat, but also darkens the glass. – unknownprotocol Jul 11 '23 at 21:23
  • Thank you, I think this solution is best suitable for me! – bud.dugong Jul 17 '23 at 11:30
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Silver color doesn't reflect sunlight to a significant degree. Shiny does, as with a highly polished metal surface. Spray paint on fabric doesn't get you shiny.

Also, it would be very difficult to get a uniform color without applying so much paint that it would be flaking off when you operate the blind or stick together, as you suspected.

isherwood
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    I will note that real silver mirrors are very good across the entire visible range. But something that looks silvery often isn't because of cost and silver oxidation issues. – Jon Custer Jul 11 '23 at 14:14