Yellowing

[RNRS001]

I'm sure much has been said about this issue but I've a question related to this. I see so many fantastic sets but I often wonder what they look like after a few years. Can anyone shed a bit of light on this? The reason I'm asking is this;

About a year ago I contacted LEGO about the yellowed parts for my Volkswagen camper. The set had never been in direct sunlight and yet some parts just looked like a different colour altogether. Some showed cracks as well, as can be seen on the photo attached. The arrows point to cracks, this isn't just dirt or hairs. LEGO had send me all new white parts as even those hidden in the set itself were yellowed.

Last year I moved to my new place and was able to get a LEGO-room. I've spend the past few weeks building pretty much every town set from 1980 to 1995 until I ran out of space. Once this was finished it was time for the "grown up" sets. I was able to put the Volkswagen Camper back together with the new parts from LEGO. While building I realized that the blue from the seats had turned grey while it'd been in a box for a good 3 months. I realized that with many of those newer sets I noticed cracks as well. The Unimog has cracks in the orange parts, the yellow big crane truck has broken parts... 

Putting everything back together from the eighties made me realize that some white parts from that era are not as yellow as the white parts from that Volkswagen Camper. I've about 5 broken pieces from that era as well. LEGO was just of better quality I think?

I see the Lamborghini has colour issues... I really like LEGO but I've refrained from buying the Ghostbusters car because of issues like these. Hence me asking. White doesn't stay white. Blue doesn't stay blue. Grey turns green/grey... What do the big sets look like after just a few years?

[Alexandrina]

Parts don't seem to yellow at a consistent rate. I think exposure to sunlight has an effect - your photos show what I've also experienced, studs that are covered by over bricks tend not to discolour as much or as fast - but that's not entirely the case, and even within a set you can see the discolouration happening at different speeds. I have next to me set 75182, bought new in 2017 and assembled on the day of purchase, and having been on my shelf ever since. The parts are from the same box, have had the same exposure to daylight, and on some the yellowing is clearly beginning while other bricks are as bright white as when the set was first opened. Unfortunately yellowing is inevitable, since it's a property of the plastic itself; sooner or later, every white brick will turn yellow. There are posts on Eurobricks with suggestions for combating the yellowing - I can't vouch for these, since I've never tried anything myself, but it does appear to be possible to restore white bricks to their original colour. I'd guess that any part with a sticker on is impossible to salvage without removing the sticker in the process, but who knows?

To be honest, if you're into Lego enough to have a Lego room, and you want the Ghostbusters car, I'd go for it. Certainly don't hold out in the hopes that Lego fix yellowing once and for all, because I can't see that happening any time soon!

As for broken bricks: I've never broken a brick myself (except for a plant piece which I shut in a door hinge when I was younger!) but I've come across many from joblots. The broken parts have tended to be older bricks (1970s-1990s) rather than post-millennium bricks, with no correlating to colour, but I can't vouch for my anecdotal experience being gospel.

[koalayummies]

Its worth noting that fluorescent bulbs can emit ultraviolet radiation. So even in a blackout curtain room that gets zero sunlight but is lit by CFLs for example can be exposed to UV. Its interesting to see the contrast between the covered and uncovered parts of the bricks varying so significantly.

[Toastie]

What I don't get: Why are LEGO bricks supposed to "last" (just in terms of changing color) "forever"? Is there any other plastic material that people know of, which does not do that? Plastic material that has the following other characteristics: Clutch power. Can be swallowed and comes out through the natural human digestion process unaltered. Put together and taken apart a thousand times (LEGO is meant to be a building toy). When lit up, it does not act as fuel. Etc. etc. etc.???

Best
Thorsten

[hagridshut]

I have many pieces that are discolored at different rates.  

Intensity, angle, and amount of time of sunlight exposure seems to be related to the pattern of discoloration.  While it did initially annoy me that some of my white bricks turned yellow and blue bricks turned a greenish hue, I've just accepted it now as an unknowable event.  It never crossed my mind as a child that sunlight exposure would affect some LEGO pieces this way, but have no effect on other LEGO pieces.  My belief is that in the future, the only pristine and color accurate models of many old LEGO sets, will be high resolution 3D digital representations.

[Alexandrina]

  On 3/9/2021 at 2:43 AM, hagridshut said:

I have many pieces that are discolored at different rates.  

Intensity, angle, and amount of time of sunlight exposure seems to be related to the pattern of discoloration.  While it did initially annoy me that some of my white bricks turned yellow and blue bricks turned a greenish hue, I've just accepted it now as an unknowable event.  It never crossed my mind as a child that sunlight exposure would affect some LEGO pieces this way, but have no effect on other LEGO pieces.  My belief is that in the future, the only pristine and color accurate models of many old LEGO sets, will be high resolution 3D digital representations.

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It's worth remembering that it's at least theoretically possible to remove the yellowing - so there's nothing stopping somebody restoring all the bricks in a set to their original colours. 

[RNRS001]

 

 

  On 3/7/2021 at 1:42 AM, Toastie said:

What I don't get: Why are LEGO bricks supposed to "last" (just in terms of changing color) "forever"? Is there any other plastic material that people know of, which does not do that? Plastic material that has the following other characteristics: Clutch power. Can be swallowed and comes out through the natural human digestion process unaltered. Put together and taken apart a thousand times (LEGO is meant to be a building toy). When lit up, it does not act as fuel. Etc. etc. etc.???

Best
Thorsten

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I'm not expecting them to last forever though. What does surprise me is new white parts seem to yellow a lot faster than the parts I've got from the eighties. I own 6379 and those parts have yellowed the same way the white parts from the Volkswagen camper have yellowed. One is over 30 years old, the other was just 5 years old. The stable was put together several times and all white parts had been used heavily when I was a child. The Volkswagen camper had been put together 2 times and its parts had always been in a closed box.

  On 3/6/2021 at 3:44 PM, Alexandrina said:

To be honest, if you're into Lego enough to have a Lego room, and you want the Ghostbusters car, I'd go for it. Certainly don't hold out in the hopes that Lego fix yellowing once and for all, because I can't see that happening any time soon!

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I realize the yellowing happens eventually and I don't mind it. Nothing lasts forever, my Fisher Price Garage from the eighties is just as yellow as the average LEGO brick. But a set that's just 2 years old showing discolouring already is unaccepting, really. You expect the parts to last a child's lifetime wouldn't you? 

Hence the question. It's easy to say "Just buy the set" but if parts start to break, yellow and crack on a set that's there for display value only it's not really living up to its promise, I think? 

[Alexandrina]

  On 3/9/2021 at 7:20 AM, RNRS001 said:

Hence the question. It's easy to say "Just buy the set" but if parts start to break, yellow and crack on a set that's there for display value only it's not really living up to its promise, I think?

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Parts breaking are not a common occurrence. Even on dark red and reddish brown bricks, during the period when they were known to be brittle, most of the time you would be fine. Bricks in other colours, being displayed long term rather than dismantled, are very unlikely to just break. 

In any case - and I promise I don't mean to be rude here - Lego to me is a construction toy at its core. Yes, you build the model and display it for a time. But if all you want is something to sit on your shelf forever, why not buy a model? If you're going to be dismantling the set at some point, bricks eventually going slightly yellow won't be a huge issue - when you rebuild, you can use nin-yellowed bricks. 

[Toastie]

  On 3/9/2021 at 7:20 AM, RNRS001 said:

The Volkswagen camper had been put together 2 times and its parts had always been in a closed box.

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This is really weird indeed.

I also do agree with you on the "should not break" issue, of course - as @Alexandrina has pointed out. That is another league. And with my bunch of bricks it really hardly happens at all.

But back on the yellowing issue - which naturally occurs.  You said the model/parts was/were mostly in a box. Was that box (unintentionally) exposed to heat? My LEGO space is in the attic. There are two rooms up there - in one I have to survive Zoom meetings for about a year - so last summer in installed a little air conditioner. The other (smaller) room next to my though gets really hot from time to time. A temperature sensor (oh yes, ESP 8266 - it is just one door (=4 m) away from my chair, but it is way cooler to call up a website ... )  told me: 43°C = 109°F.

Or exposed to anything else? Ozone for example?  Had it been sitting in sunlight for some time?

I am asking because I am curious. Heat? Difficult. Oxidants? Thinkable. Sunlight? For sure. However, it could also be that once you "trigger" a chemical reaction (by e.g. light) yellowing could very well be of radical chain type reaction. Not fast (this is what they are usually), but more of type "persistent"; once triggered in the material, there may not be that many radical scavengers. But: Just wildly speculating.

As said: Light for sure, the longer the exposure, the yellower the formerly white brick. OK, that tails out of course, as once the upper molecular layers have reacted, there is naturally an end, as you can't see into the bulk material.

Interesting.

Best
Thorsten

P.S.: Searched a bit the web ... as usual, there is so much garbage out there. But this one seems to be of decent nature:
https://www.polymersolutions.com/blog/what-makes-plastic-turn-yellow/

The last paragraph is of interest, as it goes along the lines I was speculating

"Of course, UV radiation isn’t the only factor that can cause plastics and polymers to age. Exposure to visible light, extreme temperatures, humidity or exposure to solvents can also cause a polymer to fail over time. When it comes to yellowing, however, UV light is often the primary culprit.

Getting back to your game console, it probably sat atop your TV for years — catching some rays — before you packed it away. Even though it’s been sitting in darkness for a while, the damage was already done and yellowing occurred. UV radiation was also the source of the yellowing in the case of the medical tubing failure. It turns out the patient was an avid sunbather, so the tubing got a much higher dose of UV rays than the manufacturer anticipated."

 

Edited March 9, 2021 by Toastie

[Toastie]

Here is something for you guys interested in the chemistry of yellowing, degradation, whiting, repeated degradation ...

https://deskthority.net/viewtopic.php?f=2&t=6084

Now, there is the usual speculation and misinformation you will find again and again in forums and on the web in general, however, look for the entries of the user "Chyros" - he is apparently a chemist , for example here: https://deskthority.net/viewtopic.php?p=228113#p228113  and here https://deskthority.net/viewtopic.php?p=228424#p228424

He talks about the Bromine containing fire retardants as well - which make of course not that much sense as cause for the yellowing of modern LEGO ABS, as it has been banned in the US since 2004 or so. I do not believe that the lawyers at TLG take it up with the Justice Department in the US. Well, who knows. But seeing them on their knees when the Osprey Technic set hit the fan ... no they won't.

The thing is: Yes, oxidants as bleach - or much better - H2O2 at rather high content percentage + sunlight can make the plastic white again - but just to accelerate the degradation processes after whitening. Makes sense; a polymer structure always suffers from (rough) oxidation. Color may "return" to white by bombing the degraded chemical bonds responsible for the >discoloring<, but the integrity of the polymer cannot be healed by such a rough treatment - actually such bombing always causes some more or less serious collateral damage. The analogy to surface treatment with H2O2 + sunlight is close to "aerial bombing".

Oh well. Chemistry rocks.

Best
Thorsten

 

[BrickObsessed]

Sun or oxidation? Maybe dust? Dirt from the air? Have you tried washing? Plastics do change color over time.

  On 3/9/2021 at 7:44 AM, Alexandrina said:

In any case - and I promise I don't mean to be rude here - Lego to me is a construction toy at its core. Yes, you build the model and display it for a time. But if all you want is something to sit on your shelf forever, why not buy a model? If you're going to be dismantling the set at some point, bricks eventually going slightly yellow won't be a huge issue - when you rebuild, you can use nin-yellowed bricks. 

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Same. I mean, I buy sets. I build them, admire them, gaze at them, even analyze them. But after a few weeks or months, they get dismantled. At some point, I want to create a new one out of them or reuse them, so to speak. 

Edited March 10, 2021 by BrickObsessed

[hagridshut]

  On 3/9/2021 at 9:01 PM, Toastie said:

However, it could also be that once you "trigger" a chemical reaction (by e.g. light) yellowing could very well be of radical chain type reaction. Not fast (this is what they are usually), but more of type "persistent"; once triggered in the material, there may not be that many radical scavengers. But: Just wildly speculating.

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I am convinced that there is some kind of chain reaction that happens.  

Decades ago, I used White Brick, Modified Facet 3 x 3 x 2 Top to create terrain.  Only the exterior facet was exposed to any kind of light.  However, years later, the entire part started to yellow, even the inside surfaces that had not seen any sort of illumination for a long time.

[dr_spock]

Aren't stablizers added to the plastic to keep those free radicals from uprising?   I guess there is a limit when the stablizers are exhausted fighting the radicals.

It seems to happen to non-LEGO plastic too.