Grapeseed oil can help enhance the moisturizing properties of your soap. It is light-weight and does not leave a greasy sheen on your skin after use, making it appropriate for more delicate skin types. Soap makers often use grapeseed oil as a superfatting oil, added to the mixture after the base oils and lye water have been combined. In this capacity, the oil stays in its natural state and makes your soap ultra-moisturizing.
The ingredients for your grapeseed-oil soap will vary depending on your method. Melt-and-pour soap makers will require a base soap, fragrance oils, grapeseed oil for superfatting and any desired coloring. Cold-process soap requires a base oil (you can use grapeseed oil for this), lye, fragrance oils, distilled water, grapeseed oil and desired coloring.
For melt-and-pour soaps, melt down your soap base in the microwave. Stir in your fragrance oils, along with the grapeseed oil, and pour the mixture into soap molds. In cold-process soap making, you will first add lye to distilled water. In a separate container, melt the grapeseed oil and other oil bases. Add the lye water to the oils. Stir vigorously until the mixture thickens a bit, and then pour into molds.
When working with lye, you must take the proper precautions. Never handle lye without wearing safety goggles, gloves and long sleeves. Do not breathe in lye fumes. Never leave lye unattended if you live with children or pets. Always add the lye water mixture to the oil base, and not the other way around.
One soap recipe using grapeseed oil is the Lotion Bar. Melt 4 oz. of shea butter or mango butter with 5 oz. of grapeseed oil. In a separate container, melt 4 oz. of beeswax. Combine the two mixtures and stir in 2 tsp. of your desired fragrance oil. Pour into soap molds and allow several hours for cooling.