Why Do Lego Bricks Turn Yellow? (How To Fix It)

Why Do Lego Bricks Turn Yellow? (How To Fix It)

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If you’re a Lego collector, the chances are that your collection has reached a significant size over time. 

 Some people enjoy creating the sets and putting them on display, others build them and then carefully dismantle their sets to store them away, and many more will simply break their creations apart and pop them into storage.

Whatever type of Lego user/collector you are, if your collection has grown large enough you may have noticed slight variations in the tones of each of the colors.

In particular, the white, blue and light grey Lego bricks can begin to become tinged with yellow. 

With the white and light grey bricks, the change over time into a yellow tone is noticeable, while for deeper colors such as dark blue, the same thing that causes the yellowing causes the brick to appear an even deeper blue. 

Lego bricks start to yellow a bit because of heat and age. Legos that are kept in the freezer throughout their lifetime do not yellow while those kept at room temperature will start to yellow. 

Of course Legos yellowing isn’t a simple thing as some people believe that the exposure to the sun causes Legos to start to yellow while others till feel that it is age and nothing can be done to stop them from yellowing. 

Let’s take a closer look at the cause of this yellowing, and what can be done about it.

To see the most popular Lego sets on the market currently just click here 

What Causes Lego Brick Yellowing? 

The exact cause of yellowing on Lego bricks is a hotly debated topic in the fan forums around the internet, with everyone from newbies to hardened collectors to organic chemists weighing in on the topic.

Yellowing has been seen in bricks that are stored in the sun, but also in bricks that have been stored away from any light sources. 

However, this only appears true when bricks are stored in warmer locations. 

Some Lego fans have gone to the extreme of placing their Legos in bags and storing them in the freezer and these same fans have reported no yellowing at all in bricks stored this way.

When sunlight strikes an object, the light is partly transformed into heat energy. Since we know that bricks can yellow whether or not they are in the light, but not if they are cold, it seems the most likely reason the bricks yellow is due to heat.

It is thought that the flame retardant used in Legos breaks down over time, allowing a brownish decomposition product that will leach to the exterior of the Lego brick, giving it that yellowed look.

The good news is that it is possible to restore the original color, which I will cover below, but this yellowing will occur again as more of the flame retardant breaks down and moves to the edge of your Lego bricks.

Can You Prevent Lego Bricks From Turning Yellow? 

Some Lego fans have tried keeping all of their Lego pieces neatly stacked and packed together to minimize the air getting to them in the hope that this helps, others keep their collection in airtight bags, but neither of these appears to prevent the yellowing.

Storing them out of direct sunlight and in a cooler area seems to help reduce the yellowing of Lego bricks, but the only clear cut method we’ve seen is to pack your Legos into a container and pop it in a fridge or freezer. 

This might seem a bit extreme, but for the most ardent Lego collectors, anything is worth it if it preserves the original look of the bricks.

What Can Be Done To Fix Lego Yellowing? 

The good news is we have a fix for this problem! 

I will give you a basic and an advanced method to follow, so do whichever you feel most comfortable with.

Method 1 – The Simple But Slow Option

Both methods have the same beginning point, which is the use of hydrogen peroxide. This is a method originally found by retro gamers to restore their beloved consoles to their original colors, but Lego fans found it and have had great success with it.

Hydrogen peroxide is easily available in most countries, generally at a low concentration. In the US, hydrogen peroxide is generally only available in 3% solutions, but it will still do the trick.

1. Half fill a suitably sized container with hydrogen peroxide.

2. Add the bricks that you are trying to restore.

3. Put the solution in direct sunlight, the brighter and warmer the better.

4. Wait. This is a slow process and will take up to a week to see results.

5. Each day, give the contents a small stir to ensure all edges are exposed to the hydrogen peroxide solution.

6. When you are happy with the results, or a week has passed, pour out the peroxide and wash the Legos in cool water, pat dry with a towel and then leave to air dry.

If you follow the above process, most yellowed bricks should be restored to their original tone. The bricks are often reported to be more ‘grippy’ after being treated, meaning they will lock together more firmly, but this should fade away with use.

Method 2 – Faster But A Little More Complex

If waiting a week doesn’t appeal to you, you can speed up the process by adding sodium percarbonate to the hydrogen peroxide. 

No, you don’t have to be a chemist to get hold of this, as it is the active ingredient in most a variety of “Oxy” cleaning products. 

The most popular option is Oxy Action Crystal White. 

Even in a low light situation, such as a cloudy winter day, this additive will cut the reaction time down from days to hours.

Remember to stir the solution hourly when using the Oxy method to ensure you get the best method. Be sure that whatever Oxy product you elect to use, you use one that is free of colorants, as any dye introduced will negatively affect your Lego pieces.

What Not To Do! 

My final word of advice is this– do not attempt to clean your Lego pieces with bleach! 

Whilst bleach will remove some or all of the yellow tinge, the action of bleach upon the Lego material will lead to it becoming pitted and rough, completely defeating the objective of preserving your Lego in its original, pristine, state.

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