Soap moulds are a vital component in making soap by hand. Soap moulds come in a variety of shapes and sizes and can be purchased relatively cheaply from many outlets. The right mould is important because it dictates both the shape of the soap and the way it cools.
When cold process soap is put into a mould it continues to react, which is why you must always treat new soap as still harmful. It can still burn you and must be treated with care. Freshly poured soap will heat up thus it must be placed in a mould that can accommodate changes in temperature.
Pouring soap into a metal mould is for this reason not advised as well as anything that might stifle the exchange of heat between the soap and its mould and the surrounding air. Air must be allowed to circulate around the soap as it cools over the course of the next few hours.
Types of Soap Mould
Soap moulds come in a variety of types and all are cavity moulds. They have a cavity into which the liquid soap is poured and then left and allowed to cool before removing the hardened loaf.
1. Silicone Cavity Soap Moulds
Here are a small selection of silicone cavity moulds available in the UK. As you can see, very simple silicone soap moulds can be found easily and are available in a range of shapes and sizes. All of these types of mould will accomodate cold process, hot process and melt and pour soap.
2. Boxed Silicone Cavity Soap Moulds
For making larger soap loaves and batches, a wooden boxed cavity soap mould is ideal. This type of mould comes with a supporting box that the silicone mould fits into. This type of mould is more usually found on Amazon and and by going directly to the manufacturers website. Make sure you always line the box you use to pour into. If you do not you'll ruin the soap AND won't be able to get it out of the mould without breaking it which will result in a major facepalm moment.
3. Lining Your Own Soap Mould
Of course you can make your own soap mould out of just about anything within reason! A shoe, a flowerpot, a drawer, just as long as the soap can breathe and the container can get hot without it being dangerous. I used to make soap in plastic food containers. This will work but is not advised. The plastic can get hot too and if the soap leaks across the membrane that holds the soap it could react with the plastic.
A very common way to do this is be lining something safe with baking paper. Try to get the smooth not the textured kind, unless you want to! Line the inside of the mould making sure to create a completely watertight junction. If you use a wooden box mould this is less of a worry. For anything that is NOT wood however, make sure the lining will not leak.
There are a variety of soap moulds on the market in the UK that serve a number of different uses. Working your way through from paper liners to box moulds is a sensible approach. For cold process soap, recommend starting with a baking paper liner so that you do not waste money if soap making is something you will not be doing too often. Baking paper is more than sufficient if folded carefully and can rival silicone if you are good at it. This can save a lot of money. If you are going to be making melt and pour soap however it won't make much difference so use anything you can. Melt and pour soap isn't real soap and so won't go through any chemical reactions, thus it will only cool down, not get hot after pouring. Ultimately the box moulds are better value for money and provide the best results. If you are planning on making soap often then boxed silicone mould are most appropriate.