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Restoring Discolored LEGO Bricks

(Written by William)

Have you ever built a LEGO creation only to scowl down at the few pieces that were discolored? Or have you avoided picking up used LEGO bricks for similar reasons? Given enough time, LEGO bricks can show the signs of aging. Sure, we may have grown out of using our teeth to remove parts, but dirt and discoloration can still add up.

I was having this very conversation with a fellow member of my LEGO User Group. The member in question has a vast collection of old bricks and he rarely buys anything new. However, none of his pieces look bad. They are just as bright and clean as the latest sets to hit the store shelves. Turns out, he has a method to clean LEGO that he swears by. So, since I have a lot of time on my hands these days, I gave it a shot.


When I had the conversation about reconditioning LEGO pieces, we were specifically talking about age-related discoloring. The biggest culprit for me has always been white. Though I have found other colors to change with time as well. Thus, for my first experiment, I wanted to restore my discolored white pieces.

The other issue I have to deal with is dirty bricks. You know, that layer of filth that finds its way and clings to pieces. You can use dish soap to remove the dirt, but then the parts creak and crackle. This is in part due to that layer of solution that is used to keep the brick from sticking to the molds. So, I threw those bricks into the mix as well to see if the method I learned about will do anything for that (see before picture above).

Turns out, after a couple of hours of using the method, both the discoloration and the dirt were cleaned off the parts (see after picture above). Additionally, I found that the pieces didn’t show signs of that creaking noise as they do when using dish soap. Needless to say, I went from potentially throwing away old LEGO to fully restoring them!


There are two key elements for this procedure. First, you’ll need enough hydrogen peroxide to submerge the pieces you wish to recondition. Second, you will need a container that can hold the parts and peroxide and allow sunlight in. And that’s it!

The before and after photos I have included here are parts that were left for roughly two hours. However, my friend did say if you have parts that are really bad, it is just a matter of leaving them for more hours. Just remember to check on their progress.

One thing my friend stressed was that the sunlight was essential for this to work. So, in order to be thorough, I tested this out. I found a number of discolored parts and left them overnight in the peroxide inside my house, away from direct sunlight. Turns out, in the morning, they were still discolored. So, I put those same parts out in the sun and checked them around the two-hour mark. Sure enough, the sunlight restored the parts back to their original color. To be clear, I placed the tub of parts outside in direct sunlight. There was no window in the way of the sun’s light hitting the pieces. And I did go outside on occasion to move the parts around so they were evenly exposed.

The nice thing about this method is that it’s easy and relatively cheap to do. I got a small bottle of hydrogen peroxide from a local dollar store, as I didn’t have too many parts that needed restoring. But this process can easily scale up. My friend buys hydrogen peroxide in gallon jugs when he finds them in surplus sale. And he uses a small wading pool so that he can treat a large amount of parts all at the same time.


The peroxide should disinfect any parts you have, but I’d also recommend keeping your vats of chemicals away from pets and small children. I have roaming critters in my backyard from time to time, so I placed my tub on top of our green waste garbage can. It’s not a surefire way to keep it away from a determined beastie, but it makes it awkward for them to reach the tub. And I just monitored the container regularly to make sure birds didn’t think it was some new-fangled bird bath.

Another point that is worth mentioning is that I did not try this process on printed elements. I’m uncertain how the peroxide would interact with paint on elements or stickered pieces. I’m fairly certain though, if you picked up engraved bricks from a third party, they should be fine provided no special inks were used.

Overall, it was a simple process to do and rather affordable. I even used a funnel to pour all the hydrogen peroxide I used back in its bottle, since multiple uses seemed to be perfectly fine for the solution. This will allow me to stretch that one dollar even farther. So, if you have some reall old ugly parts you just can’t bring yourself to throw away or use, give this a try and bring them back to life! If you would like to learn more about the method, JANGBRiCKS demonstrates it in the following video.

What do you think? Have you used the hydrogen peroxide method before to restore discolored and dirty LEGO parts? Or what other method do you use? Feel free to share and discuss in the comment section below!

And you might also like to check out the following related posts:

{ 27 comments… add one }
  • Ian June 11, 2020, 11:51 AM

    I have heard of this method, but never tried it myself. I may give it a shot as I have some discolored white and blue bricks. The blue ones are almost dark green!

  • brickmaster June 11, 2020, 12:05 PM

    White bricks will discolor even if you keep them out of sunlight and in storage. I’m nost sure what causes this, but it’s a real thing many people experienced.

    • Stephen Cheesman December 16, 2020, 12:35 PM

      What percentage of peroxide are you using

      • Thita (admin) December 16, 2020, 12:51 PM

        Stephen, you can try the regular hydrogen peroxide available at pharmacies, but in my experience, it only works on slight discoloration. For heavily discolored bricks, use the stronger hydrogen peroxide used by hair salons. I believe it’s like 40%.

        • Amy June 3, 2021, 10:04 AM

          Where could you buy the stronger peroxide? I can’t seem to find it.

          • Thita (admin) June 5, 2021, 6:32 PM

            Amy beauty supply stores usually carry them as it is used for bleaching hair. 🙂

  • mr. marmelade June 11, 2020, 1:04 PM

    I have seen the method work, but I don’t want to disassemble my mocs. Many of them are custom, and it would be a huge task to document how they were made and then put them back together. Maybe I could take them apart in chunks, and soak the chunks. But would that work?

    • Will June 12, 2020, 1:24 PM

      You could always try leaving the MOC together and just creating a larger bath for them.

      I know taking apart a MOC is a pain which is why I’ll often just say, “Now it’s an aged XYZ.”

  • Håkan June 11, 2020, 1:33 PM

    Hmmm, yeah, I have a balcony I could use for this, I guess. I have very big windows now in my apartment, but sunlight generally feels detrimental to both my Lego and comics collection, so I might add some UV filter or something.

    (Currently I have my window blinds down constantly, so I guess it might look a bit shady to my neighbors…)

    • Håkan June 11, 2020, 1:36 PM

      And yeah, some of my old white bricks look closer to modern tan. (Although I have so many white bricks I guess I should pick out a selection of more useful bricks, such as the crater baseplate, first before trying this out…)

  • Galadriel June 11, 2020, 2:45 PM

    We tried this method, but we ended up needing to use the stronger hydrogen peroxide that beauty salons use. The regular one just wasn’t strong enough. The stronger one did work, but now I wonder if the regular one would have worked too if we leave the tub out longer, or wait for a sunnier day.

    • The Other Mark June 11, 2020, 3:29 PM

      I have been thinking about trying this, but keep putting it off. I suppose it can be a cool science experiment. Does the hydrogen peroxide damage the bricks in any way?

      • MagickChicken June 11, 2020, 7:28 PM

        Regular bricks should be fine; I would do a test with translucent ones and screen-printed ones, though.

        • Håkan June 12, 2020, 6:01 AM

          There was another trick that you could use floor polish for translucent bricks, apparently. The post was linked below the article.

          • Thita (admin) June 12, 2020, 10:42 AM

            Yes, that method works very well. I have used it many times. But it’s not so much about cleaning, it’s about restoring scratched up translucent pieces. 🙂

  • Santa Ron June 11, 2020, 5:48 PM

    I have a large winter village moc I put up every year and have tried all the tricks to restore discolored “white” brick. The peroxide in the sun works the best but it only lasts for a few months and the discoloring comes back.
    I decided it was more trouble than it was worth. I just replace the discolored pieces now. It’s worth the extra money and it looks better.

    • Will June 12, 2020, 1:28 PM

      Yeah, if your models are set up in conditions where the discoloring happens often getting new bricks will be a longer fix for your purposes.

  • MagickChicken June 11, 2020, 7:27 PM

    I find it interesting that sunlight is necessary for the cleaning to occur, since peroxide breaks down in sunlight (that’s why it comes in an opaque brown container).

    I wonder if the sunlight is causing bubble nucleation, and that’s helping it penetrate the dirt. There are peroxide-based contact lens cleaners with an iron disk that decomposes all the peroxide in a few hours while creating an effervescent effect; I should play with a couple of those and see if I can get the same result without sunlight.

    Or an ultrasonic jewelry cleaner. . .

    • Vivid Bricks June 12, 2020, 11:57 AM

      As far as I understand the matter (no scientist); the discoloration by sunlight is caused by UV light ripping the oxigen of the stabilizing agent in the plastic. This is causing free radicals (bromide I believe) to be exposed at the surface, and causes the yellow/brown color.

      Hydrogen peroxide (H2O2) + UV light causes the H2O2 to break up into H2O (water) + O (oxigen). This Oxigen ion in the solution wants to have jolly friends again and is binding with those free radicals in the plastic and thus restoring the original color. Of course, if the parts are exposed to sunlight again, over time it will eventually damage the bonds again and discoloration will reoccurr.

      • Thita (admin) June 12, 2020, 1:25 PM

        Very interesting. Thanks for the explanation. 🙂

      • Will June 12, 2020, 1:31 PM

        That is cool!

        It’s like we’re giving the LEGO bricks a breath of fresh air!

      • Will June 12, 2020, 1:37 PM

        That makes me wonder, could you restore a LEGO brick if you had a vacuum chamber and then saturated your bricks with pure oxygen?

        We need some university students and a lab!

  • Hobbes June 11, 2020, 9:51 PM

    I used this many times. If I ever sell a used set, I process them this way before to make sure everything arrives in perfect shape(colours!) Works well for white, the old gray, and the blue (works on the other stuff as well but the other stuff does not change colours as much so it is less noticeable). Works also flawlessly on decorated pieces. I usually leaves my pieces significantly longer than 2 hours – more like between 4 and 6 hours. I also make sure the parts are completely submerged in the solution – no floating parts.

  • RYAN M Conrad April 28, 2021, 7:24 AM

    Does this work with faded darker colors like black, or brown?

    • Thita (admin) April 28, 2021, 7:49 AM

      Ryan, I did actually try it on black, and it worked really well bringing back the shine of some dulled and scratched up pieces. So, you might want to give it a try. 😀

  • Zack August 13, 2021, 5:04 AM

    Do you have any tips for accidental overbleaching using this method? I left some light bluish gray parts out for a couple days because some of the parts didn’t look like they were changing at all and unfortunately some of the bigger plates I had in the bath came out with a very whitish/bleached hue.

  • Jim September 27, 2021, 8:03 PM

    Does anyone think using an ultra violet light would work the same as or better than natural sunlight? As I understand it, its the suns ultra violet rays activating the peroxide.

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