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Discolouration/fading of bricks

CortezCortez Member Posts: 19
edited April 2011 in Everything else LEGO
How quickly does Lego discolour or fade if left in natural light? I have a few sets on display in a room with double aspect windows which cast a large amount of sunlight in summer. None of the models are in direct sunlight. How big is the risk of colours changing and is this something which can happen in months or years?


  • davee123davee123 USAMember Posts: 832
    I believe it's pretty variable. Direct sunlight is bad, and we've heard some people say that it can happen in only a few months if the conditions are right.

    However, the problem is that ABS is very unpredictable. The molecules in ABS don't form a uniform structure, they're sort of random blobs. The older your parts, the more likely they are to be subject to yellowing, but it depends on the particular "batch" of the element. Within the same set, we see some elements yellow very quickly, while other elements (with the same exposure) resist yellowing for much longer.

    White elements are probably the biggest risk, with old gray and blue following close behind. Other colors seem to be less likely to be affected.

    Luckily, there's a solution if your elements get too yellowed-- check out Retr0bright (or other similar mixtures).

  • fox171171fox171171 Member Posts: 45
    I've wanted to try RetroBrite, but can't seem to find any Hydrogen Peroxide, 10 to 15% strength. Highest I can find is 3%. Tried hairdressers, as suggested, but no luck.

    Found this:
    But smallest amount is 4kg 35%, for $100. A bit more than I want to pay. Shipping can be an issue.
  • IstokgIstokg MichiganMember Posts: 2,326
    Davee123.... gotta love your "random blobs" analogy. I've noticed this in many sets over many decades.

    Ironically Cellulose Acetate (which ABS replaced 1963-70), which has problems with warping, has a tendency to hold its' whiteness on white bricks better than ABS... but unfortunately it has a tendency to warp.... although climate control does play a factor in CA warping... I have a CA set (717 Junior Constructor USA Samsonite of 1961-65) that has no warping at all on the CA parts.
  • brickmaticbrickmatic Member Posts: 1,071
    Actually, part of the reason why different bricks hold up better than others is because of additives. Small amounts of additives are added to each batch of plastic that enters the molding machines. These additives are pigments to color the plastic, chemicals with flame retardant properties, antioxidants to help slow down the degradation of the plastic, and additives that modify the physical properties of the plastics. Small differences in the proportions of the additives results in differences in how well the bricks will age. This is why bricks produced at the same time, in the same color, and stored together in the same conditions will often have different levels of yellowing. What is really telling is when you look that a model that had been assembled a long time ago and look closely at the white bricks, you'll see that generally bricks with the same shape have the same level of yellowing. This is of course because bricks with the same shape were made in the same molding machine with the same batch of plastic.
  • drdavewatforddrdavewatford Hertfordshire, UKAdministrator Posts: 6,742
    edited April 2011
    ^^^ I recently tried the Vanish + peroxide + sunshine method and the results were.....unexpected (!)

    The results were such that I decided to discuss it on my blog and share some photos. You can read about it at the link below if you're interested.

    Suffice to say the outcomes can be unpredictable and you need to be careful.....
  • davee123davee123 USAMember Posts: 832
    So, the flame retardant (what causes the yellowing, IIRC) is added by LEGO at the time of molding, rather than by the plastic supplier? I was under the impression that it was added when the ABS granulate was formed, but I admittedly have no clue.

    That would make a lot of sense, though-- many elements that I've seen have yellowed according to what appears to be the batch they were made in rather than the particular color or date of the set.

  • jgadgetjgadget Member Posts: 192
    @Dr.D - I've been tempted to have a go at making some Retr0Bright, but not got around to it yet.
    I'll admit that I haven't studied it in depth, but I thought the best results were obtained by applying a thin coating of the gel formula.
    Why did you choose to go with the immersion approach?
  • IstokgIstokg MichiganMember Posts: 2,326
    From what I understand... the supplier used to be the Bayer Corp. (famous for their aspirin).... there is an entire genre of LEGO "test brick" collectors collecting Bayer Bricks (with either A, B, C, D, E or F on the brick studs in a rainbow of different colors). The "A" bricks had the least "clutching power"... the "F" bricks had the most clutching power.

    Bayer used to mix the colors into the ABS pellets. From what I gather now TLG does the color mixing before the moulding process, using non-Bayer ABS plastic... hence the decrease in the quality of the end product.

    Very old LEGO bricks used to have a lot of "bleeding" (previous color used in the mold would show up on the edges of the new colors put into the mold). This was supposedly attributable to the MRA (mold release agent).

    An interesting fact about ABS plastic... it is the "B" (Butadiene) in ABS that absorbs the smoke for those complaining about "smoky" LEGO. A solution (although impractical) for eliminating the smoky smell is to put the bricks into a vacuum chamber for 24 hours and the smoke will be eliminated.
  • brickmaticbrickmatic Member Posts: 1,071
    @drdavewatford I find found your blog post on your attempt to reverse discoloration entertaining! I guess you won't be trying to boil the solution again anytime soon :p Thanks for sharing your experience with the Retr0Bright process.

    On a side note, I believe the reason Lego changed the color of gray to bley is to make those bricks more resistant to discoloration.

  • brickmaticbrickmatic Member Posts: 1,071
    @Istokg Oh, that's good to know about the vacuum chamber. That wouldn't actually be very impractical for me.
  • davee123davee123 USAMember Posts: 832
    @brickmatic - the color change for gray had nothing to do with practicality, unfortunately. I think everyone in the hobbyist community would've been at least begrudgingly accepting if that were the case! :)

    The change to new gray from old gray had more to do with the aesthetic look of the grays and browns. Certain people at LEGO thought that the palette looked very dull and drab (the colors hadn't really changed since they switched to ABS from CA that I know of-- maybe Gary knows better though!)

    Anyway, supposedly in 2000, they started testing new colors that looked "new" and "bright". The thinking was that nobody would care if they didn't match EXACTLY with the old colors (boy, were they wrong!), and that it would make their product a bit better and more cohesive. Basically, they believed they were improving the product aesthetically.

    Hobbyists threw what will probably forever be known as the biggest hissy-fit EVER by AFOLs. Many people speculated that it was some sort of *practical* reason that encouraged the change, because they couldn't fathom that the company would do something as silly as change the color just to make it look better. Hence, many people began effectively coming up with conspiracy theories, such as:

    - Reduce the tendency for yellowing
    - Less toxic for kids
    - Less flammable
    - Cheaper
    - More recycle-able and/or less environmental impact
    - Change in molding/dying process for higher-quality molds
    - etc.

    It seemed that almost nobody could take LEGO's word for it that they did it for aesthetic reasons, despite the fact that LEGO would have lost a lot less respect among AFOLs if that were the case. But LEGO has confirmed several times that yes, it was done to make the colors look better. And they've also confirmed (subtly) that yes, in retrospect, it was probably a bad move.

  • drdavewatforddrdavewatford Hertfordshire, UKAdministrator Posts: 6,742
    @jgadget, I used the immersion technique rather than painting on gel piece by piece simply because I had lots of LEGO that needed treating and I figured it'd be quicker and easier.

    @brickmatic - glad you liked the blog posting ! Having completely nuked all that LEGO, I figured that I should at least warn others of the potential pitfalls !
  • IstokgIstokg MichiganMember Posts: 2,326
    davee123... interestingly enough... CA old gray is virtually indistinguishable from ABS old gray. The colors that are the most noticeable are red (by far the easiest to spot)... CA red is sort of a transluscent orange-red. Yellow is also a color that went from what I call "Lemon Chiffon" to regular yellow. And blue is another color... CA blue was a brighter more medium blue than the (comparatively) darker blue we know today. Black and white are pretty much the same, except on mint pieces the CA ones have a shinier finish. Funny thing is... all my CA gray plates (no gray bricks were produced in the 60s) don't quite have that shine that some of the other colors have.

    Also, when TLG switched over to ABS from CA (a process that went comparatively fast in Europe and Australia in 1963-64), it took about 8 years for the last of the USA/Canada Samsonite red and yellow CA to be used up. That's why I theorize that TLG send Samsonite their old LEGO molds (waffle bottom plates, and 1x6/1x8 bricks with cross supports)... and also their remaining old red and yellow CA they had in inventory in Billund (they probably got their fellow Dane friend's... the Maersk owners to ship a few cargo containers of CA red and yellow to Denver Colorado and Stratford Ontario. There's no other logical explanation why red and yellow CA was used until 1970, while ABS blue and white was used starting in 1963 in USA/Canada.

    One last thing about red and yellow LEGO... when TLG switched over to ABS, they (Bayer) had troubles with producing those 2 colors. So from 1963-73 Bayer added Cadmium (a heavy metal) to the red and yellow ABS pellets. This produced a darker color of red and yellow in ABS bricks of that era, This appears to be most noticeable in classic red windows/doors of that era. Sometimes Bricklink sellers incorrectly list old classic red windows/doors under the "dark red" heading.

    Although TLG showed that Cadmium would not be a hazzard to children, and would not leech out of the bricks... it was deemed to be a potential hazzard for landfills (LEGO in landfills... what a horrific thought! :-O)... so by 1973 Bayer came up with an alternative to Cadmium for producing red and yellow LEGO elements.

  • brickmaticbrickmatic Member Posts: 1,071
    @davee123 Thanks for pointing out the conventional wisdom. I looked for citations and found this, which supports your points and seems to really explain how the color change went down:

    This post makes it clear that the color palette was market tested with children before being approved and these tests were positive. I am curious, however, how the Design Lab team went about selecting the color palette that they first submitted for testing and how much of a role testing played in the design process (as opposed to the role it played in the approval process).
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