Making soap from scratch is not for the faint-hearted. Lye is a dangerous substance that causes serious burns to skin. Mixing the lye with water could result in a boiling explosion. And then there's no guarantee your lye and fat mixture will actually turn into soap. Avoid the problem by using pre-made glycerin soap as the basis for your soap recipes. Lemon-scented tea tree oil imparts a citrus scent, and the tea tree oil is soothing to the skin.
Cut 1 lb of glycerin soap into 1-inch chunks. Melt the glycerin soap in a double boiler with the bottom pot filled with water. Glycerin soap melts between 140 and 160 degrees F. Use caution, as that's still hot enough to cause a burn. Remove the top pot from the double boiler. Add 1/4 tsp. to 1 tsp. lemon-scented tea tree oil to the melted soap. Stir gently. Pour into mini loaf pans. Let completely cool. Pop out of the pans and slice into bars.
Remove the peel of oranges, lemons and grapefruit. Try not to include any of the white pith that's attached to the peel. Place the peels in a dehydrator until they're completely dry. Put in a blender, or spice grinder, and grind. Follow directions for the basic soap. Add 1 cup of the peel when you add the lemon-scented tea tree oil. Pour into pans, let cool and cut into bars.
Layered Soap Bars
Follow the basic soap recipe. Add a bit of orange food coloring to one batch of soap. Half fill the loaf pans and let set until the soap is beginning to cool but not completely set. Make another batch of soap and add a bit of yellow food coloring. Let that batch cool in the top of the double boiler until it's thick in consistency but still warm. Pour the yellow batch over the orange soap already in the loaf pans. Let cool completely and cut in bars.