I grated what was left of a puck of MWF into a mug and added hot water to fuse it together. The water was left to evaporate instead of being poured out. I compacted it in the mug and fit tightly. The mug isn't covered or sealed in any way. Now, a month later, I find it's shrunk about a quarter to three-eighths of an inch in diameter. I'm using it almost daily, so I don't think it's drying out. Any ideas, gentlemen?