Lye is very caustic and can cause chemical burns when handled improperly. But when used correctly, it’s completely safe for soap-making. When you mix lye with the oils and water properly, the chemical reaction between the ingredients means there’s no lye left in the soap. After the soap cures for six weeks, it’s safe for use on the skin. If working with lye scares you, you can also make soap without lye using the melt and pour method.