There are many options when thinking about molds for soapmaking. You can make your own from shoeboxes lined with freezer paper or reuse dairy-product containers and beverage cartons. You can utilize common kitchen containers (think Tupperware). Or you can buy wooden, plastic, or silicone molds made specifically for soap.
Self Made Molds
As you get into soapmaking, you will start noticing many things around your house that appear to be fantastic options for soap molds. Yogurt and tofu containers, waxedcardboard milk and juice cartons, the round tubes that potato chips and other snacks are sold in, and plastic food-storage containers (the kind that always seem to be missing their lids) — these all make excellent molds for soaps. Most of them can only be used once, though you can get more use out of sturdier plastic ones or by lining the molds with freezer paper. Whatever you use needs to have some “give” to it, in order to release the soap after it has set. Metal and glass are not good materials for molds — the soap will stick and be nearly impossible to get out. Anything made of cardboard or wood must be lined with freezer paper. If you do want to use a particular metal mold, never use one made of aluminum, even if you are lining it. Use only containers that held food or nontoxic materials. Before using a temporary soap mold, clean it thoroughly with soap and hot water.
There are many sizes and shapes of soap molds on the market, and they come in a variety of materials. The two most common shapes are vertical (tall and skinny) and horizontal (wide and flat). They create different bar shapes and offer different design options. Molds can be made of silicone, plastic, or wood. Raw wooden molds must be lined with either freezer paper or a silicone liner. Waxed paper will flake into your soap.
LOAF (OR LOG) MOLDS are typically used for impressive swirling, layering, and landscape designs. Loaf molds (wooden or silicone) come in all sizes. When choosing a wooden mold, look for things that will help with unmolding, such as sides that flip down, or bottoms that slide out, or silicone inserts that fit in the mold. You can purchase specialty loaf molds made out of high-density plastic that do not require lining.
They have their own set of challenges: they’re often more expensive than wooden molds, soap can stick to the plastic, and depending on the material, they can expand and contract with heat. Many soap molds come with cutters what allow you to cut bars of even sizes. A multi-pour sectioning tool is called for in some recipes that use this type of mold; it allows you to customize the look of your bars and create certain designs. It differs from standard dividers used in slab molds in that it is removed before the bars set up.
HORIZONTAL, SLAB, OR “DIVIDER MOLDS” provide a wider canvas for designs; such as most horizontal molds come with optional dividers to form uniform bars that are easily unmolded. Horizontal molds are typically made from wood and need to be lined, though some are available in plastic. Dividers are typically made from a high density, heat-safe plastic. SILICONE MOLDS — the kind commonly used for baking — are available in all shapes and sizes and work great for soap. They are less expensive than wooden molds, require no lining, and make unmolding easier, although it can be tricky to release soap as the soft sides make it possible to dent the bars. Choosing a recipe that is harder or using a soap-hardening agent such as salt or sodium lactate will help the unmolding process. One downside is that silicone can produce pock marks in the final product if the soap overheats. To prevent this, keep your temperatures low (below 120°F [49°C]) when using silicone molds.