SpanjaardThickness, excess carrier, color register or detail level, should be in principle common to all the kits of the same production, and will not change overtime. yellowing is something that happens after some time, and can happen faster (or not happen) depending on the conditions. i guess that if storing a kit in a place with big temperature differences, time will probably affect the decals more than if the kit is stored in a better place. in any case, yellowing is not something that will be present for everybody at the same time, while de thickness of the decals certainly is. so i would say that yellowing should not be included. in my opinion, if the kit is very old, there is a big change of yellowing 🙂
1 6 May, 18:14