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jd5775

Yellowing in MISB sets

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So almost all of my misb sets are from the 1990 to 1995 period. I have heard about "oxygen sensitive white bricks" and yellowing of sets that are still misb, so I am worried that I won't be able to keep them immune indefinitely.

So far none of them have shown any signs of yellowing, even in the oldest ones, do you think that if they were going to yellow, they would have by now? I keep most of them in a dehumidified basement that gets a little sunlight (not directly) and the others in a closest that also gets very little sunlight.

Is it possible to keep them new indefinitely or will they eventually yellow regardless?

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If your sets from the 90's have not yet yellowed, it is very unlikely that they will considering they are misb. It will be a fair amount of time before they start yellowing if they are kept in the boxes and in little sunlight.

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If I understand the chemistry correctly, the reason the yellowing happens is exposure to UV. The UV light transfers energy to the flame retardant, which can cause the bond with the bromine to break. Since bromine is by nature a yellowy-brown, that color will start to emerge in the bricks as the bonds are broken. (I think the bromine bonds to itself forming Br2?)

Hence, if you avoid exposure to UV, you should be fine. I've opened various MISB sets as old as 18 years, and never had a problem with yellowing. That's largely because (I think) the elements are protected from UV by the surrounding cardboard box. If you've got (say) polybag sets, where the light can get into the bag and hit the elements, you might be at risk for yellowing. Or maybe if you keep your box lids open.

The other thing to watch is moisture, which has nothing to do with yellowing. In theory, humidity can affect the bricks, but not very noticeably. Effectively, it can cause slight warping if left in a humid environment. Fortunately, the effects aren't really noticeable, IIRC. I believe it has more to do with things like clutch power, rather than pronounced warping.

DaveE

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The particular kind of yellowing you are referring to (there are two types) is not easy to avoid. I have many sets from that period that I bought MISB around 2000-2003 and put on display away from windows or fluorescent lighting. They looked good when I opened them but some pieces have become yellowed over time. This issue can also occur out of the box if the MISB set was stored in a smoky environment, but usually appears only some years after a set has been opened.

This is not caused by UV since the bricks become equally discolored on all sides, even if they are covered up by other bricks. In some cases, a few specific bricks in a model become severely yellowed while others in the same color look perfect. In my 8839, the 1x8 white plates all look bad now while the other bricks in the model are perfect. I think TLG was experimenting with a different plastic additive in that period and did something funny with these bricks without realizing it. These "bad bricks" are fortunately not that common though, and seem to occur in Technic sets more than anything else. 8880, for example, is known to contain a lot of them.

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The particular kind of yellowing you are referring to (there are two types) is not easy to avoid. [...] This issue can also occur out of the box if the MISB set was stored in a smoky environment, but usually appears only some years after a set has been opened.

I wasn't aware of another type of yellowing-- what is it that causes this? Something to do with "smoke"? Does this imply that you're in an environment with smokers? If so, I certainly have heard that the tar from cigarette smoke can cause discoloring, although I'm admittedly surprised if it made it through an MISB box.

DaveE

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I wasn't aware of another type of yellowing-- what is it that causes this? Something to do with "smoke"? Does this imply that you're in an environment with smokers? If so, I certainly have heard that the tar from cigarette smoke can cause discoloring, although I'm admittedly surprised if it made it through an MISB box.

DaveE

See the entry here on oxygen-sensitive bricks. There is no smoke in my apartment but it still occurs over time. The MISB sets where I've seen it out of the box did have a "smoky" look and obvious wear on the box though, both on the outside and inside, as if they had been stored in a grimy warehouse.

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See the entry here on oxygen-sensitive bricks.

Do you have more information about this? What sets specifically has this been noticed in? Is it only a factor with white elements, or other colors as well? It says "1989-1996" in the summary, what's that based on?

Otherwise, I'm curious about the chemistry involved there-- is it known to be oxygen? Or is it a reaction to some unknown agent in the air, and deemed oxygen based on assumption? (IE, could it be, say, Nitrogen that causes the damage?) Why has this been attributed to be more common with "smoky" environments, and what sort of "smoke" is implied? Wood-burning fireplace smoke? Cigarette smoke?

I've still never seen nor heard of this happening with anyone I've known personally in the hobby, similar to hairline cracking in various elements that's being confirmed elsewhere-- Could it be regionally based (IE have some component of climate/temperature/etc)?

DaveE

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The time frame is a pretty rough estimate and is based on the sets I have seen it in myself. It only affects white bricks as far as I know and could certainly be something other than oxygen, but does seem to be related to the air and not light. Just looking over my shelves, some sets containing these pieces include 6398, 6483, 8880, 8839, 5580 (1990 version), 5581, 8868 and 8480. These have all been built up and on display for 7-10 years, in two different houses. Others have reported it on 8880. Unlike the other sets, which only contain a few specific kinds of bad bricks, 8880 has a large variety of pieces affected by this issue.

As for the smoke inference, the two MISB sets I've observed it in out of the box (as opposed to appearing after several years on display) were 6395 and 6989, and both had that grimy appearance. I can't really tell what sort of smoke it is. The bricks in these sets also had unusually strong gripping power, which may be related. I got good prices on them on ebay though, so I can't really complain.

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The time frame is a pretty rough estimate and is based on the sets I have seen it in myself. It only affects white bricks as far as I know and could certainly be something other than oxygen, but does seem to be related to the air and not light. Just looking over my shelves, some sets containing these pieces include 6398, 6483, 8880, 8839, 5580 (1990 version), 5581, 8868 and 8480. These have all been built up and on display for 7-10 years, in two different houses. Others have reported it on 8880. Unlike the other sets, which only contain a few specific kinds of bad bricks, 8880 has a large variety of pieces affected by this issue.

As for the smoke inference, the two MISB sets I've observed it in out of the box (as opposed to appearing after several years on display) were 6395 and 6989, and both had that grimy appearance. I can't really tell what sort of smoke it is. The bricks in these sets also had unusually strong gripping power, which may be related. I got good prices on them on ebay though, so I can't really complain.

What do you mean by out of the box? I have an MISB(Well MIB since I broke one seal) 6398 that I just checked and the white parts all seem completely new and not yellowed. I can't exactly tell if the box is smoky though.

Do you think that they are in any danger of yellowing while sealed in the polybags? I'll try to get some pictures to show you guys.

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It only affects white bricks as far as I know and could certainly be something other than oxygen, but does seem to be related to the air and not light.

Is the solution to the yellowing the same? As in, can you use something like Retr0bright to reverse the yellowing? (That is, chemically speaking, is it caused by the same broken bond in the bromine?)

As for the smoke inference, the two MISB sets I've observed it in out of the box (as opposed to appearing after several years on display) were 6395 and 6989, [...] I got good prices on them on ebay though

Are there any other examples of it happening on MISB sets? Or is it just those two sets that you got on eBay? Were they from the same seller? If it's just the eBay sets, I'm inclined to think that it may have something to do with cigarette smoke, since the tar residue might explain the extra clutch power.

DaveE

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What do you mean by out of the box? I have an MISB(Well MIB since I broke one seal) 6398 that I just checked and the white parts all seem completely new and not yellowed. I can't exactly tell if the box is smoky though.

Do you think that they are in any danger of yellowing while sealed in the polybags? I'll try to get some pictures to show you guys.

Probably not, but it may become yellowed over time if you build and display the set. The only bricks in my 6398 with the issue are some 1x2 plates and 1x2x1 slopes though, about 6 or 7 pieces in total. By out of the box, I just mean an MISB/MIB set opened for the first time.

Are there any other examples of it happening on MISB sets? Or is it just those two sets that you got on eBay? Were they from the same seller? If it's just the eBay sets, I'm inclined to think that it may have something to do with cigarette smoke, since the tar residue might explain the extra clutch power.

They were from different sellers, one in the US and another in South Korea (it was a localized copy of the set). I think the 6395 auction had said the set was found in an FAO Schwarz storeroom. Those are the only examples I can recall. Another interesting thing about these sets is that several bricks (not just white ones) have a slightly dark spot around the molding mark. It's not that noticeable, but it's always around the mold mark and I was not able to easily remove it, so it's evidently some chemical reaction and not just some grime that had collected there.

I do want to try out Retrobright on all these parts but haven't gotten around to it. This yellowing looks identical to the UV-based yellowing, except that it covers the whole piece more or less uniformly.

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Otherwise, I'm curious about the chemistry involved there-- is it known to be oxygen? Or is it a reaction to some unknown agent in the air, and deemed oxygen based on assumption? (IE, could it be, say, Nitrogen that causes the damage?)

In looking around further, it sounds like the UV light is merely providing the 'activation energy' for yellowing. Once that energy has been transferred to the flame retardant, the bromine bond breaks, and can hook up with stray oxygen. Hence, if you had your LEGO in, say, a tank of hydrogen gas, or a vacuum, you could hit it with UV rays, and you wouldn't get the yellowing, since there's no oxygen for the bromine to bond to, which results in the yellowing.

The other caveat is that UV light probably isn't the ONLY way of getting the 'activation energy' necessary. I don't know the chemistry, but it could be that excessive heat or radiation could also provide the same activation energy, and cause the bonds to break.

I believe that means that while boxed elements are technically less likely to get hit by UV rays (since the box protects them), it's possible to be exposed to other forms of energy that can cause the same reaction to happen.

Just store your LEGO in a vacuum, and you'll be all set!

DaveE

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It's hard to tell from a picture but that box looks good to me. It should be obvious if you have a smoky box. In both of my cases, the inside of the box looked slightly dirty and discolored on the inside.

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Some input from my experience:

Direct or indirect UV exposure causes yellowing mainly on the exposed sides, especially on white, blue and gray bricks. In case of long-term exposure, even yellow parts are affected. I'm currently preparing an article on my use of industrial hydrogen peroxide (30%). It will be based on sets of the 80s, built once (mint) and exposed on a shelf for over a decade. White bricks have turned brown... As said before, UV doesn't affect bricks which are in closed boxes. Boxes that are exposed to direct sun light, will fade but the parts inside won't change. Note: Cellulose parts are very sensible to UV and cannot be 'cleaned'...

Smoke also causes yellowing but on a more even scale, on several sides of parts. On the other hand, it seems that less ABS types and lower pressures are affected. Boxes exposed to smoke won't be affected but some of the parts inside might be. I've encountered this a few times with sealed boxes where very specific, mostly white parts have yellowed over time. ie. The white wheel rims of a 8880 MISB set, which are apparently made of lighter ABS, have yellowed in a smoky environment.

I collect mint/MISB sets and tbh until now, I have never encountered a new set, which has yellowed bricks and that has been stored in a UV-free and smoke-free environment.

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If the sets are MISB how would you ever know if it had yellowed?

D

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If the sets are MISB how would you ever know if it had yellowed?

Schrodinger's Lego? I guess it is both at once.

Well, unless it's one of those old-school flap-top ones with the window showing some pieces.

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Schrodinger's Lego? I guess it is both at once.

Well, unless it's one of those old-school flap-top ones with the window showing some pieces.

Quantum mechanics and LEGO bricks: Never thought of those 2 together before.

Maybe this explains it:

Many-worlds interpretation

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If the sets are MISB how would you ever know if it had yellowed?

D

Because lots of the older MISB sets I own have a top flap and I opened some of them myself obviously.

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I have a question for all the experienced collectors here about the pesky problem of brick yellowing. Last March I purchased a 6973 Deep Freeze Defender that showed no yellowing whatsoever and placed it in a closet until I could display it somewhere. Yesterday I brought it out and found that every single '90s vintage white brick had yellowed drastically. Modern white bricks next to it showed no discoloration.

This closet has no windows and is lit with a ceiling-mounted fluorescent bulb. Being a closet, this light is only on for brief periods when someone needs clothes or I want to access some LEGO. This set was even under an overhang and shielded from direct fluorescent light! Other old white bricks in the same closet, such as Blacktron 2 minifigs and an Ice Planet 1704 that were directly under the bulb on an upper shelf remain pristine. I don't think it was UV because the closet is so dark and these bricks are almost uniformly yellowed, even under other bricks.

The only difference I can think of is that I placed my 6973 on top of a plastic LEGO advent calendar tray that I use for sorting. Might this cheap plastic have released some chemical to yellow the ABS? The jets and skis on the underside might be a little more yellow than the rest. On the other hand, modern white bricks in the tray didn't show any problems. Has anyone else noticed yellowing from a storage container? This makes me very concerned about using plastic bins to store LEGO, but I can't think of anything else that could have caused it. Any ideas?

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This has been mentioned/discussed quite extensively.

This post talks a lot about it, but I think it has been mentioned in other posts too.

Basically the older plastic was treated with a fire retarding agent that can cause discoloration over time. Almost all of my 90s white bricks are discolored too (yet my 90s TYCO brand bricks are the brightest white I've ever seen, so I assume they weren't treated the same or were made with different plastic, even though they feel/look like real LEGO otherwise).

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The yellowing is caused by a chemical reaction to the fire retardants added to the ABS plastic, not necessarily by UV light. People have found old sealed sets that have the bricks yellowed in the package. It seems to be a crapshoot as to if, when, and to what extent your old bricks will yellow.

You can use the retr0brite formula to restore the original color of your bricks. I used it for my yellowed classic space and futuron bricks, and it works pretty well.

http://retr0bright.wikispaces.com/

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Thanks for the replies! It sounds like smoke is often a factor, which isn't the case here. I guess my bricks just ran out of time in the last year. I'd be very interested if anyone knows the actual chemical reactions that are going on with the fire retardant and ABS. I've never tried retr0brite, but I have heard that the yellow color tends to return over time. Have you found that to be the case, and have you noticed any weakness or structural changes in the plastic from repeated whitening? I may not whiten them if the color will just randomly come back over and over.

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From what I understand, bromine is the chemical they add to the plastic. When bromine reacts with oxygen, it turns the plastic yellow. Using the retr0brite method, the hydrogen peroxide and UV cause a reaction where the bromine releases it's bond to the oxygen, therefore removing the yellow. Over time, it probably is possible for it to turn yellow again, but who knows. Mine were retr0brited around this time last year and they're still bright white.

I wish I had taken some photos, but it was a pretty dramatic difference. I don't notice any negative effects, I even soaked printed parts in the solution with no damage.

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Yes... this is not only bricks from the 1990s, but also from the 1980s as well... which is when most of my yellowed white ABS bricks are from. Mine were kept in a dark basement for decades, and they still yellowed. I had built a LEGO skyscraper with white bricks back then... and the bricks still yellowed... however in the places where bricks were touching other bricks (sort of away from oxygen)... they remained white.

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