How do you keep (newer) white bricks from yellowing?

[CSEverett1759]

Supposedly white bricks yellowing is only a problem with bricks made before they switched to a new plastic in the mid-2000's. But having just built a massive Saturn-V mod MOC, I took the Saturn V built directly from the parts that came in the set, bought from Lego, and now the entire thing's horribly yellowed. Meanwhile recently only some specific bricks from Lego's modular buildings diner went fully yellowed in what seems to only have been a year or two. While the diner was on display on the main floor of the house, the rocket has been sitting in a dark closet for at least the last six years! (Hasn't been opened in long enough that it smelled when I did open the door.) It's possible the Saturn V had yellowed before that point though.

Which brings up the question - with "last several years" bricks, is there any way to stop them from yellowing, or do you just need to completely remove them from any possible sunlight (or not display them in a room with any windows), or is there a way to safely display them in a house full of windows on the west side?

Thanks.

[icm]

Dunno where you heard that yellowing is only a problem for bricks made before the mid-aughts. I never heard that 

[Mylenium]

All plastics age and will change colors, even modern ones. There is no magic way of avoiding that. It just shows up on bright colors as apparently they reflect all colors of the spectrum. Darker colors simply absorb them and thus the effect is often barely noticeable. Everything else is a myth based on false information. LEGO are going to introduce a more opaque, more stable white pigment this year, but even that won't change basic physical and chemical laws. And officially they never made any statements that would support your hearsay, anyway. Pigmented pellets typically only make up below five percent of the whole mix, anyway, and in turn that means that there is a whole lot of milky-ish transparent base polymer that will still do its thing and eventually turn into those shades of yellow and brown that combined with white will blend into those off-white shades. Yes, of course it helps to keep your models away from aggressive light with a high amount of UV just as it helps to control air humidity and temperature, but ultimately there just is no way to keep plastics perfect for forever.

Mylenium

[CSEverett1759]

8 hours ago, Mylenium said:

All plastics age and will change colors, even modern ones. There is no magic way of avoiding that. It just shows up on bright colors as apparently they reflect all colors of the spectrum. Darker colors simply absorb them and thus the effect is often barely noticeable. Everything else is a myth based on false information. LEGO are going to introduce a more opaque, more stable white pigment this year, but even that won't change basic physical and chemical laws. And officially they never made any statements that would support your hearsay, anyway. Pigmented pellets typically only make up below five percent of the whole mix, anyway, and in turn that means that there is a whole lot of milky-ish transparent base polymer that will still do its thing and eventually turn into those shades of yellow and brown that combined with white will blend into those off-white shades. Yes, of course it helps to keep your models away from aggressive light with a high amount of UV just as it helps to control air humidity and temperature, but ultimately there just is no way to keep plastics perfect for forever.

Mylenium

How much UV (indoor) can you get away with? One north-facing window that the blinds are always closed on, but somewhat direct line of sight? (New windows that supposedly block 85 percent of UV.)

[Toastie]

5 hours ago, CSEverett1759 said:

How much UV (indoor) can you get away with

You cannot get away with it. It is not solely the UV, it is everything capable of triggering (slow, very slow) chain reactions on the surface/inside the polymer. Depending on the actual formulation, sometimes yellowing occurs faster, sometimes later. And 2 ... 5 ... 10 ... 30 ... years is nothing for a slow chemical reaction. It is called half-lives in physics and chemistry. 

UV certainly accelerates yellowing. Without UV, it will happen as well. 

Best
Thorsten