We can’t solve a problem if we aren’t aware of its existence. One appealing aspect of railroading is the sheer, awesome, mass of our subject matter.   Prototype rolling stock is huge and the challenge as a modeler is finding a way to capture that in miniature.   A very, very subtle modeling problem that we face is that glossy surfaces don’t scale down.  A glossy prototype locomotive or freight car looks real in a photo because…well…because it is real.  What if we want to model a subject that has such a glossy surface?  We have a problem.  As we move from prototype to model, our challenge becomes apparent.    A level of sheen that looks fine on the real thing looks like a toy when applied to a model.  We lose the sense of mass.  As modelers, we need to develop an awareness of this inconvenient reality.  Each person needs to decide how they want to handle modeling newer or generally cleaner looking subjects. Personally,  I think I’d take the route of applying a dulling agent and just forgo additional weathering.