MFH resin yellowing?

[MoFo]

After digging some MFH kits out of my stash recently, I noticed that the resin has yellowed *significantly* since I bought them. They were pristine and white when new, but now they are cream-coloured, with a faint orange tint. Is this standard for their resin, or is it something to do with the way I'm storing them? (I'd be surprised if it's the latter - they're in their bags, in the boxes, untouched, in a temperature controlled basement - but who knows?)

More importantly, does it pose any problems in building/painting/decalling? Should I worry about paint compatibility or the resin attacking other materials?

[primabaleron]

I don't have much experience, but I have been making MFH kits for two years. Some of them were bought after they had been lying on a shelf for a few years. I do not notice the difference in the preparation and the effects of painting the old and new MFH resin.

[JamesB]

It has also happened to my F2007. No problem at all. MFH resin is white because it has a tint component (AFAIK, but I'd be really surprised if it was otherwise), yes it's strange how white can overcome a yelowish cream color, but same happens with enamel paints, which BTW are not that different chemically to the urethan resin.
It´s just oxidation, I guess. Nothing terrible. I´ve seen similar yellowing on my own resin. And I have painted decade old resin with no problem.
OH, no, what the hell, I was teasing you, if it´s yellow you cannot use it any longer, please sell it to me at ten bucks

Haha no, serious, no problem at all I imagine

[Seema]

I also have some MFH kits stored in my apartment. Some are around 6 years old. The only kit that has a cream color is the Mclaren MP4 / 4, all others are white. The 4/4 has already come with this resin color. I haven't painted the hood yet, but I couldn't find any problems with the other resin parts. Paint with Tamiya or
Zero-Paint primer and its colors.

[F1tommy]

Most resin will yellow as it gets older. Should not cause an issue. Shrinking also happens and can cause fit problems after many years of storage.

[MoFo]

Wait, you're telling me I have to BUILD my stash? Damn!

[Badi]

Well, as a chemical engineer that has left resin process for more than 20 years, I am not sure about this specific case, but I feel I must bring some explanation, at least try it...

I dont believe this is the case, if your model were well storaged, but yellowing of polyurethane as a result of UV radiation can happen.

"The synthesized aromatic polyurethane undergoes photodegradation with gradual change of its colour. The photochemical degradation of the polyurethane is associated with the scission of the urethane group and photooxidation of the central CH2 group between the aromatic rings. These reactions are combined with the yellowing of the polyurethane surface."

basically sun light and oxidation as mentioned before.

I hope it helps...yayayaya