So my WD model arrived about 10 hours ago--first time that I've tried this material. The surface of the model was smooth, slightly waxy, and had an apparent light shine under light. Within the time frame in which I've had it out of its delivery bag, the surface has been exposed to a slightly moist environment of ~25 degrees C under a compact fluorescent bulb, and has developed a "gritty" surface that has the texture of sandstone over the exposed surface. The underside of the surface exposed (visible internal details) has been unchanged. The model also has a distinct odor whereas one was not noticeable before. Does anyone know the chemical process that this is undergoing?