Jighooper I have made countless molds from Durhams water putty. After a while they will start to break down. The key is to not pour to many at one time. I generally pour 6 - 8 at a time. I’m still using molds I made two years ago. When I make a mold I bake them at 250 degrees for an hour to get them dry. Pouring a mold that still has moister will spew lead like a volcano. Before I pour I dust the cavities with talcum powder for better lead flow. If I can figure out how to post a picture I’ll show you a couple I have made.