Lego Quality Reference

[Graupensuppe]

Is part 25893 made from a special type of plastic? I noticed that some of my spare ones (that were not exposed to a lot of light) have become very yellow. The one on the right is for comparison. I haven't seen this happen with any other clear pieces in recent years.

[Toastie]

4 hours ago, Graupensuppe said:

Is part 25893 made from a special type of plastic?

Well, could be. The change of the resin used for trans clear was announced by TLG but of course no disclosure on the polymer. This was discussed here and there; here is only one reference:

https://forum.brickset.com/discussion/33843/are-trans-clear-lego-or-all-trans-parts-now-made-out-of-a-different-plastic

It is speculated that the polymer is now of the type MABS ((Methyl) Methacrylate Acrylonitrile Butadiene Styrene) - more down below on its properties as copied from this link:

http://polymerdatabase.com/Polymer Brands/MASB.html

Methacrylate Acrylonitrile Butadiene Styrene

Transparent ABS

Properties

Methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) is a clear engineering and commodity thermoplastic that has excellent transparency, high impact strength, good stiffness and good resistance to chemicals. The properties of MABS resins depend on their composition. The butadiene portion provides flexibility and high impact resistance¹ whereas the methacrylate-styrene-acrylonitrile portion provides strength, good dimensional stability, and creep resistance.

MABS is widely used in the household appliances and consumer goods industry. It is also used for toys, office accessories, industrial housings and covers, reusable drinkware, and medical devices.

 

I am not sure at all though of the "greener" approach TLG has chosen; they have added methyl-methacrylate to the copolymer mix - which is as green as dark red is. I believe this was much more driven by the structural properties of MASB - which are much closer to ABS as polycarbonate possibly can be. Also, you can adjust these structural properties by changing the monomer percentage composition (see above).

And yes, sunlight + MABS my well result in what you are seeing. Particularly because MABS is somewhat foggy and thus absorbs light more efficiently as poly carbonate does - and that absorbed light may induce chemistry that leads to what you observed.

Best
Thorsten

 

[Graupensuppe]

MABS seems to have been introduced in 2018/2019 though. Some of these pieces are older than that (2016, 2017).

[Toastie]

16 hours ago, Graupensuppe said:

Some of these pieces are older than that (2016, 2017).

OK. Now does the material of these darkened pieces "feel" different from other trans pieces made from poly carbonate? The latter being considerably "stiffer" than pieces made from MABS?

Also: How long have these parts been in the sun? Were they as foggy as the one not exposed to light? That "fogginess" points to a material other than poly carbonate, which is usually crystal clear (windows, bricks, other household materials, etc.). Maybe TLG has experimented with MABS before? It has been around for some time ...

Best
Thorsten

[Graupensuppe]

1 hour ago, Toastie said:

OK. Now does the material of these darkened pieces "feel" different from other trans pieces made from poly carbonate? The latter being considerably "stiffer" than pieces made from MABS?

That's pretty hard to tell with pieces that are this small.

Also, the ones that became yellow were not exposed to sunlight. They were in a box with other spare parts. The one used for comparison probably hasn't yellowed yet because it is the newest one I have, it's only three weeks old.

Edited April 27, 2021 by Graupensuppe

[Toastie]

On 4/26/2021 at 3:09 PM, Graupensuppe said:

(that were not exposed to a lot of light)

Oh man - that happens when you attend a Zoom meeting and read EB posts in parallel - sorry. Missed the "not". Minus mal minus gibt plus ...

Well - then the trans clear pieces may face the same issue that others have with white and some other lighter colors as well. Let's see: these yellowed pieces are 4 - 5 years old, correct? White pieces do yellow within that time span as well, some more, some less, certainly the process is accelerated by "light" exposure. Which is not the case here and which has also been reported elsewhere, including yellowing of old trans clear parts - which simply either means that poly carbonate can yellow as well or MABS has been in use for longer time than we believe. Or none of this 

Here is another thread that looks at yellowing for mostly ABS but also other plastic materials:

 In any case: Plastic material does degrade. And depending on the co-polymer mix maybe faster or slower. I can also envision that TLG is playing around with the mix to adjust mechanical/structural properties. And since TLG can't wait for years to see whether these brick mixtures survive unchanged or not ... it may be a game of trial and per definition no error.

All the best
Thorsten   

[MaceWindu]

I haven’t been monitoring the situation with Reddish brown parts for some time now. Has the quality improved recently? No exceptions? I would appreciate it if someone would elaborate on that.

[AFOLguy1970]

FYI for those who own a modular Downtown Diner.  I was looking at the interiors today and had not done so in a while.  When I got to the gym (the level right above the diner), I discovered that 5 out of 16 reddish brown clip pieces used to hold the boxing ring section together had broken at the hook.  Certainly, this is very frustrating, and I disassembled the ring entirely to avoid the eventual breakage of more of these parts.  I will probably try to order the black version of this part and use them in place of the reddish/brown parts.  I have to wonder how many other problems I have yet to discover in the many sets that I own and display.  Online Pick a Brick has this as HOLDER Ø3.2 W/TUBE Ø3.2 HOLE       ID:6341968/44873

 

[Pirate_King_1982]

I’m going to be buying a copy of Barracuda Bay second hand but NIB for $100AUD more than it originally cost. Just wondering whether anyone could tell me the current quality of the reddish brown specifically, but also other colours now days? I’m going to open the box and assemble it as it would be a shame not to display a set I instantly fell in love with, even though I missed out on buying,  just wondering if I need to take any special care building, displaying and maintaining it.

[Lyichir]

5 hours ago, Pirate_King_1982 said:

I’m going to be buying a copy of Barracuda Bay second hand but NIB for $100AUD more than it originally cost. Just wondering whether anyone could tell me the current quality of the reddish brown specifically, but also other colours now days? I’m going to open the box and assemble it as it would be a shame not to display a set I instantly fell in love with, even though I missed out on buying,  just wondering if I need to take any special care building, displaying and maintaining it.

Reddish Brown has been fine for a couple years now—IIRC I think it was early 2020 that Lego announced through their Ambassador Network that they'd finally eliminated the issue in new sets. As such, earlier sets might still have defective parts but post-2020 sets like Barracuda Bay or the Crocodile Locomotive ought to be fine.