Play Clay Tips Make sure children's hands are completely clean before beginning a clay or dough project. If clay gets too dry, renew it with a few drops of water. If clay is too sticky, knead in more flour, cornstarch or baking soda. Cover extra clay with a damp cloth while working to prevent drying. To color clay: either knead in food coloring or cake-decorating coloring paste. Most clays can be colored with acrylic paints when dry.