I have a reading light whose temperature is very high even on the lowest setting (marketed as 3000K, but feels higher). I want to filter away all of the blue light it emits. My first idea was to get a piece of transparent red plastic, (similar to those Japanese "checksheets") cut it to size, and glue it to each light source.

Here is what the object looks like. Skip to 1:35 for a view of the parts I'd have to cover. https://youtu.be/oY0W-FDZ8bU?t=95

  1. Is there a better way of doing this? For instance using some kind of paint or gel?
  1. If not, is there a better material to use than plastic?
  2. Would it have to be red to block out all of the blue light, or could orange still get the job done?
  • Welcome to Lifehacks. The colour to use to eliminate/attenuate blue is yellow. Both are spectral colours and opposite to each other on the color wheel diagram. canva.com/colors/color-wheel
    – Stan
    Commented Mar 18, 2023 at 14:14
  • @Stan Thank you for the correction. Looks like I mistook the kelvin rating for blue light attenuation.
    – Qwokker
    Commented Mar 19, 2023 at 14:19

1 Answer 1


The Mellow Yellow Reading Light Lifehack

You can make a transparent optical quality filtering "paint" by mixing gelatine powder with water and adding yellow food colour to the mix.

Apply (brush or dip) the filter gel when the surface of the luminary (bulb) is cold and let dry. Multiple layers are additive and have greater effect than a single layer. After some use, the gel may fade but it can be remixed and reapplied to suit your taste.

Of course, you can also make 'caps' to clip/slip on the ends if you don't want to put the gel directly on your new reading light. Alternately, appropriate-size transparent pill bottles can be cut in half to use as clip/slip on filters. Use the bottoms coated with the gel filter.

Some experimentation will be necessary for you to find the right concentration of the gelatine and water. You'll want it to be a bit more concentrated than for making it to eat for desert.

Good luck.

  • I recently bought a low-power mains LED night light which was too stark. I cut a section from the orange bag of a well-known supermarket chain, wrapped it, secured it with an elastic band and snipped off the surplus plastic. It's now just right – but it isn't a reading light. Commented Mar 18, 2023 at 18:13
  • Thank you, this is a very promising idea.
    – Qwokker
    Commented Mar 19, 2023 at 14:17

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