This stops all your chemical sediment developing a sludge at the bottom of your container. Be careful not to use too much water or this experiment will not work. Crystals will start to form around the item you have placed in the container, you should start to see results after three days to three weeks. Epsom Salts make the fastest crystals, with very visible results showing after just three days. In fact, if you leave the Epsom Salts for the three weeks you will have formed a very smooth rock.
Salt takes three days to start to develop, and can keep growing for about a week.
Sugar takes the longest to show results, and may not be the best of item to use with impatient children. However the crystals grown are beautiful to see, they just take a couple of weeks to develop and can be left for up to three weeks in their container as long as they are stirred daily. Copper Sulphate will make lovely blue crystals, but if you would rather use salt or sugar, you can add any food colouring to the initial boiled water mix, and your crystals will grow in that colour. Try reds, blues, greens and yellows, in different containers, for an impressive result on your shelf. This prevents them from being damaged or knocked about.