Model railroading can still become the bleeding edge of chemistry.
My 'original' thin foam inserts for coal hoppers seemed fine, until one day I touched one lightly and put my finger right through it. Near dust.
Full replacement on 30 cars. No idea why the foam just disintegrated to dust.
Mark Graulty's printed tie strips fell apart from a reaction to Pliobond, but it took two years to happen.
The most annoying has been the noticeable yellowing of Woodland Scenics Deep Pour Water on my Hickory Bridge Ttrak module, that's a triple that's entirely bridge, and after about five years the water is beginning to look like it's coming out of a toxic mining site. And unfixable.
Add zinc pest, plenty of that in old Rivarossi. And the inexorable warping of styrene when used with solvent glues like Testors, years later. And white gear syndrome.
The biggest surprise has been that I've been resin casting now for over 20 years, and the leftovers from my very first ever pour (pulled out of a plastic cup with a stir stick still embedded in it) is slightly yellowed, but still solid and strong with no sign of structural deterioration. It's a wierd paperweight on my desk with a tongue depressor in it.
Oh, and the new one - a RP-printed casting that's assumed as being LED-cured, that really wasn't quite, drill into it and discover it has a soft liquid center. That apparently never dries out, either. Not so Jolly Ranchers.
