How to choose your soap mold?

Soap molds come in a variety of shapes, sizes, and materials. It is essential to think about the type of mold you will use when designing a soap project.

The mold will determine the size of your batch and can influence the ingredients and drying time. One of the most popular options is the silicone mold. They are easy to clean, do not require a liner, and come in a variety of shapes and sizes.

Other mold options include recycled containers, plastic molds, and wooden molds. Each has benefits that can impact your soaping experience.

Silicone molds

• Pros: Easy to release soap with flexible material, easy to clean, no need to line the mold, long life, professional looking bars.
• Cons: Soap takes a little longer to unmold, soap may become speckled with bubbles if overheated.

Silicone molds are extremely popular because of their ease of use. Sturdy yet flexible, silicone molds make it easy to cold-release, melt, and pour soap.

The key is to break the airlock by gently pulling the sides of the mold away from the soap. If you encounter resistance when removing the cold process soap, stop and let the soap sit in the mold for a few more days. It's not worth tearing the sides or bottom of your project!

Soap takes longer to harden in silicone molds because there is no air in contact with the soap. Sodium lactate is a key additive to use when working with silicone molds. Sodium lactate is a liquid salt that helps produce a harder bar of soap that lasts longer in the shower.

Sodium lactate also helps the soap harden faster in the mold. This means that instead of waiting 3-4 days to unmold your project, you can often unmold the next day! We recommend adding 1 teaspoon of sodium lactate per pound of oil in your recipe to cooled lye water.

In addition to being easy to unmold, silicone molds are easy to maintain. After removing your soap from the mold, hand wash the silicone mold with warm water and dish soap. Let dry and the mold is ready to use for your next project!

Although silicone molds are sturdy, we do not recommend putting them in the dishwasher. Also avoid any harsh scrubbing, such as copper sponges, as they can scratch the shiny finish on the inside.

Recycled molds

• For: Creating unique, cost-effective and environmentally friendly shapes
• Cons: Shapes are not uniform, may need to line mold, mold may only be good for one use

Any container can be turned into a soap mold with a proper liner. If the container is plastic, the soap can be poured directly without a liner. The most common options are yogurt cups, pudding cups, and tofu pots. Cardboard milk cartons are also a good option, as the inside is usually coated with a non-stick coating. Recycling items and boxes from your home is a great way to save money on molds and create eco-friendly and unique-looking bars.

One downside to recycled molds is that they are not very sturdy and may produce bars that are not completely straight or uniform. If you are looking to create professional looking bars in a consistent manner, other mold options are better. The container should not be used for food storage once it has been used to make soap. Depending on the strength of the container, it may only be good for one soap recipe.

Most recycled containers will need to be lined with freezer paper to prevent the soap from sticking. If the soap were poured directly into the cardboard, it would stick to the box.

Metal or glass containers are not recommended for cold process soap molds. One reason is that it is extremely difficult to remove the soap. If you use rigid molds, they should be lined with freezer paper... otherwise you may never be able to remove the soap! The other reason is that lye reacts with many metals, including aluminum, tin, and zinc. Sodium hydroxide lye reacts with metal to release hydrogen gas, which is very dangerous. Avoid all metal containers for soap.

Wooden molds

• Pros: Easy to isolate/gel phase, long lasting, produces large quantities of soap, professional looking bars.
• Cons: May require anti-mold coating, may soften over time when exposed to raw soap from drippings and normal use, prone to overheating.

Wooden molds are another popular soap mold option. They are sturdy, cost-effective, and act as excellent insulators for cold process soap. They can also last for years and years with proper storage and care. Burl wood molds are made from premium birch plywood that is both sturdy and durable.

Wooden molds should also be lined with freezer paper to prevent the soap from sticking to them. To make this process easier, many burl wood molds come with a silicone liner. When lining a mold, keep in mind that freezer paper is very different from wax paper. Freezer paper is sturdier and won't melt at high temperatures.

One of the best features of wooden molds is that they insulate the soap well. This makes it easy to get a full gel phase throughout the soap. This is important to keep in mind when insulating wooden molds; since they naturally insulate the soap, it is not necessarily necessary to place the mold on a heating pad. If you want to avoid the full gel phase, you can place the mold and soap in the refrigerator or a cool place.

Plastic molds

• Pros: Wide variety of shapes and designs, cost effective, ideal for short runs, professional looking bars
• Disadvantages: Can be difficult to demold, requires more time to demold, risk of soda ash, difficult to make large production batches

Plastic molds are best suited for melting and casting and can also be used for cold process soap. Plastic molds come in a wide variety of shapes and sizes.

Most plastic molds have an individual cavity size. The smaller size means that the molds do not insulate the soap as well as larger loaf or sheet pan molds. We do not recommend placing plastic molds on a heating pad, as they can melt or warp if they get too hot.

Instead of using the gel phase to prevent lye formation, you can spray the soap with 99% isopropyl alcohol every 15 minutes for an hour. This helps create a barrier to protect the top of the soap. You can also reduce the fat content to 3% or the water content to 10%.

The trick is that cold process soap can be a little tricky to remove from plastic molds. It can take up to a week to unmold plastic molds. If you are using a plastic mold for your cold process project, we recommend using plenty of hard oils (palm oil, coconut oil, cocoa butter, etc.) to help the soap harden. Adding sodium lactate also makes a huge difference.

It can take a little while to find the right type of mold for you. Personally, silicone molds have become my new go-to after years of using wooden molds. But if I want my soap to gel, wooden molds are still my favorite. When using plastic molds, I make sure my recipe contains solid oils, and I always use sodium lactate. When teaching my friends how to make soap, I usually recommend that they try soap with recyclables first, to make sure they enjoy the process. Each mold has its pros and cons, and it all comes down to personal preference!

What type of molds do you prefer? I would love to hear what you think in the comments below.