I admit, I was skeptical that yellow faded legos could even be “cleaned” to look like new again until I saw some posts online about it.
But it turns out all it takes is three things you probably already have around your house:
- Hydrogen peroxide (the stronger the better!)
- OxyClean (ie: sodium percarbonate)
- Sunlight (or a UV lamp)
Lego bricks (unless they’re very very old) are made of ABS plastic. The surface layer contains chemicals (bromine) that cause it to yellow or eventually brown over time when exposed to UV light. But some smart people figured out how to non-destructively reverse the chemical reaction that causes the yellowing. Put a little oxyclean in the hydrogen peroxide in a jar, put your parts in, and leave it in the sun for several hours or a couple days and the mixture fizzes and your legos start to look new again. The amount of time needed to make the pieces brand new will vary depending on how yellowed they are. Stronger concentrations of hydrogen peroxide is the way to speed this up.
If you want to get really fancy and clean really large items like old computer cases and keyboards while you’re at it, you can make a gel out of the cleaning solution by adding glycerin and xanthan gum (from your favorite store that sells gluten free cooking products) so you don’t have to immerse your pieces. But for legos, they have so many crevices that I think dunking them is generally easier.
I picked a few pieces to do a trial run, since I had the ingredients on hand to try it, and left them in the sun in the mixture for the better part of the afternoon in a window getting partial sunlight, stirring periodically. When I dried the pieces all off and compared them to the control pieces (uncleaned bricks of similar levels of yellowing), there was definitely some improvement on all pieces, though it had not yet been enough time in the sun to completely whiten the pieces (and the ones on the top got cleaner than the ones on the bottom of my tupperware). So I would categorize this experiment as one worth repeating, and worthwhile.
As an FYI, I have yet to test bricks with writing or designs on them, but I have heard some colors (like gold space figure accents) do not hold up well to cleaning. You’ll notice in my picture above I also tested a blue brick with some yellowing, which makes them look greenish, and it’s a little bit out of gamut so it didn’t photograph well, but it did appear to reduce the yellowish tinge, though I have yet to decide whether it looks the same color as “like new” or slightly different. On a lot of the new parts they’ve changed the colors “slightly” since the 70’s so it’s hard to compare.