Make your own soap

Don’t be put off by all the safety equipment, making soap is good clean fun. It’s science and magic, and a fun creative craft too! Before you go out and buy any of the equipment or protective gear, ask if your neighbour or a friend has any first.

Why make your own soap?

• It’s cheap! This recipe works out to about 50c per bar of soap. See the soap cost calculator at www.soapcraft.co.nz
• You can avoid the animal fats used in many store-bought soaps
• You can avoid chemical nasties
• You control what washes down the drain to the sea
• You choose your own natural exfoliants, colours, and scents
• It’s a fun family craft project/science experiment

Read this first!

Caustic soda can burn your eyes and skin – treat it with great respect. Never add water to caustic soda – it can react instantly, blasting the chemical out of the container. Instead add the caustic soda in small amounts to the water. Always wear eye protection. Also, don’t be tempted to wash your utensils straight away. The caustic soda is very active and shouldn’t be washed down the drain to our ocean. Wait till the following day to do the washing up OR wipe everything with a rag and next time you put it in the washing you will have soap thrown in too.

What to wear

• Glasses or safety goggles
• Rubber gloves
• Face mask (optional)

You’ll need

• Kitchen scales
• Stick mixer (or a strong arm and whisk)
• Large stainless steel bowl or pot
• Large measuring jug
• Thermometer ($16 from www.soapcraft.co.nz)
• Tablespoon, large mixing spoon and rubber scraper
• Tea towel and cooling rack
• Chopping board and knife
• Molds – I made mine out of two 1 litre juice and milk cartons. Used paper coffee cups are good too – if you don’t use a keep cup yet.

Ingredients

• 175g caustic soda (NaOH) aka sodium hydroxide. This is a super-strong alkaline, the opposite to an acid, but equally as dangerous on your skin or inhaled – hence the protective gear. Once mixed and left to cure this chemical changes into a safe substance. Soap cannot be made without it. Available from www.soapcraft.co.nz or some supermarkets
• 600g coconut oil
• 600g olive oil
• 475ml water

Optional extras

• 1 tablespoon honey, for caramel colour
• 1 tablespoon oats, sugar or salt, for scrubbing texture
• 10-30ml essential oil

Step-by-step guide

Step 1: Equipment

Gather all your equipment together so you don’t need to rummage in the kitchen with your safety gear on.

Step 2: Protective gear

Goggles, mask and gloves on? Okay, you’re ready to go! Turn on the extractor fan, or go outside.

Step 3: Caustic mix

Measure out your 175g of caustic soda and add to the 475ml water in your jug. You must always add caustic soda to water – never the other way around! Stir, and with your thermometer, watch the temperature instantly skyrocket. Avoid breathing in the fumes.

Step 4: Add some colour

Add a tablespoon of honey to the mix and watch the golden colour change. Cover your jug with a tea towel (to save your dog, moggy or a sparrow getting ill) and leave outside, out of reach of children until the mixture cools to 30-40°C.

Step 5: Prepare the oils

Back inside, measure out 600g of each oil on the kitchen scales and add to your bowl or pot. Pop this on the stovetop to heat until the coconut oil has melted. Turn off the heat and watch with the thermometer until it’s cooled to 30-40°C again.

Step 6: Combine and blend

Once both bowls are within the 30-40 degree range, pour the caustic soda mix into the oil mix, stirring with a spoon. Use your stick blender or whisk to thicken the mixture into a creamy custard. Be sure not to splash about as the NaOH is still very strong and hazardous. Pour in your essential oil now to add a nice scent. In a few minutes the mixture will become ‘trace’ – this is when you can see the ripples appear and stay on the surface – only then is it ready to pour.

Step 7: Pour into molds

Arrange your molds in a line so you can pour and fill them easily. I put a tablespoon of oats in the bottom of one of mine for added scrubby texture. Fill your molds and use the rubber scraper to get every last drop from the bowl.

Step 8: Cover and cure

Cover your molds with a tea towel so they cool slowly. Leave for a few days, or at least 24 hours. Turn out the molds, and cut your soap into bars. Leave on a cooling rack, covered, for 4-6 weeks to cure.

Why cure it?

Leaving soap to cure ensures all the caustic soda has time to become inactive. You also need to get the proportions of caustic soda and oil right: if there’s too much caustic soda, or if you don’t mix it enough the soap will be brittle and may have streaks of caustic soda in it and must not be used.