How to clean yellowed LEGO bricks to make Classic Space sets look new [News]

This is very old news for some of you, but I just realized that we never blogged the breakthrough discovery of a way to restore the original color of yellowed LEGO bricks.

LEGO discoloration experimentLEGO fans have discussed this problem for years, even concluding (correctly) that ultraviolet light can contribute to faster yellowing of colors like white, blue, and old light gray (some of the key colors of Classic Space sets). Fans like sugegasa have experimented with the effects of sunlight on the new grays, but nobody could quite figure out how to reverse the effect on older, yellowed bricks.

That is, until now. The same problem apparently happens with other ABS products, such as the casing on older computers and video game consoles. A group of gamers over at Retr0Bright have proved conclusively that the original color of yellowed ABS can be restored by using hydrogen peroxide.

Tim Goddard gave it a try on his yellowed LEGO bricks.

Cleaning yellowed LEGO bricks

Success! In brief, the problem isn’t dirt so much as a chemical reaction in the visible surface layer of the ABS plastic itself, caused by UV rays in sunlight. Immersing the LEGO bricks in a hydrogen peroxide solution permeates the surface and reverses that chemical change.

Learn how to get those Classic Space sets looking like new again at Retr0Bright.

Important: Standard disclaimers apply. Your mileage may vary.

12 comments on “How to clean yellowed LEGO bricks to make Classic Space sets look new [News]

  1. JimmytheJ

    Whoo! Gleaming whites, here I come! A whole tub of yellowed parts will once again have meaning! Yee-hah!

    Plus, I could buy yellowed parts cheaper and make them better! Gah-hoo!

    Any problems to printed parts? I don’t wanna ruin the old goodness, anyone experimented with easily replaceable bley parts?

    What measurements should I use?

    Should I wear plastic gloves?

    Is there any hydorgeney peroxidey residue?

  2. DocRod

    what a coincidence, I’ve just been trying this myself in the last week.

    I’ve had good success with the arrowroot variant recipe, I added glycerol as an experiment. I could post some before and after pictures that show much more yellowing than those in this article, but guess I can’t in the comments section.

    The white and greys worked really well, the blue faded a bit, but this was on a second run. Logos seem to be unaffected.

    I also only needed about 6 hours in the sunlight.


  3. gigahound

    I would like to caution that if the parts are left in the solution too long they can become a lesser shade of the color they are supposed to be.

    You really should read the entire site before trying this.

  4. Artahn

    I use that stuff in my ears. It gets rid of dirt and oils and such. Everything else stays perfectly in tact.

  5. SFlash

    I also use a sonic water cleaner. I’ve had some decent results with yellowed legos going white, but use it to mainly sanitize my legos without a single chemical. I have had incredible cleaning success with old nasty bricks. Every old lego that comes in my house gets this treatment.

  6. Fred

    Another fun cleaning tip:
    If your bricks have a good nasty layer of dust on them, a dry paint brush (I like a 1.5 inch brush) works wonders.

  7. darinS

    for questions on printed bricks. “The original “Oxy” mixture does not affect paint or stickers, unless the stickers are held on with a water based glue or are paper stickers.”

    That’s from the source article. Not they don’t test on LEGO bricks, but I would assume it should be fine. Still test a brick that you don’t care for first.

    This is the article I found:

  8. Kermit

    Reading the Retr0bright page I understand that the yellowing of the plastics is caused by the bromine added to the plastics. The function of this being a flame retardant which is needed for electrical equipment to stop it from catching fire.

    I’m wondering however, why should this be necessary for Lego bricks ??

    Does Lego still use this material in their product?

    This because it is believed that this material can have some health issues. and according to Wikipedia some of these material are banned by some European countries.

    Maybe the yellowing effect is therefore caused by something different in Lego.

    Maybe I should write an email to the Lego group with these questions.

  9. David4

    Yeah I wouldn’t use this stuff if the kids are going to play with the pieces. The active ingredient in Oxiclean (or Oxy Power) is a pool chemical.

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