It's time for me to begin surface prep/cleaning for some new (non-WoG) shapeways ships in FUD, and, well, I painted some two (or maybe 3) years ago. And it was fine at the time, but after two years, now they "sparkles" showing through the paint. They look more or less like a little glitter got spilled on them. Storage has been in a clear plastic tray, air conditioned, in the vicinity of a window. (But there's sparkles on the bottom too.) Strangely, WSF from the same order doesn't have them, only FUD. Surface cleaning was, um, straight up undiluted Simple Green poured right out of the bottle. (Had it on hard, didn't look up anything.) For, um, somewhere between "overnight" and "a day" (or more.)
Could that be the cause? (WSF was in the same said bath.) And if it is or isn't, what should I do this time so it won't happen again? Does "hour soak in soap and water" go far enough?

Thanks.