I've had tarts last anything up to 40 hours for a 1oz tart,& fragrance the whole donstairs of my house, probably would have gone on for longer but I wanted a change, using Ecosoya pb & fo's said to be not great quality, so I'm hoping to try out some "better" oils soon. I recently got some rubber ice cube moulds shaped like hearts, stars, shells, fishes & penguins, great for 1/2oz mini tarts. Like everyone says they are loads of fun to make & a good way to try out a new f.o. Have fun with your tarts. Sally.