In this activity, we'll use a mixture of coconut and olive oil, with sodium hydroxide (sometimes called caustic soda), to make a solid soap. Homemade soap is particularly good for your skin because the glycerine formed as a byproduct of saponification remains in the soap, to soften your skin. The experiment takes about three hours, but your soap product will need to be 'matured' over a four- to six-week period before you can use it.

What You'll Need:

For 250g (about 1/2 pound) of soap, you'll need the following:

• 32g (1-1/8 oz.) solid sodium hydroxide*
• 125g (4 oz.) vegetable fat
• 55g (1.7 fl. oz.) pure olive oil
• 55g (2 oz.) white coconut oil*
• 100cc (3.4 fl. oz.) distilled or rain water (not tap water) **
• 5g (3/16 oz.) essential oil* of your choice, or the juice of a lemon (optional)
• goggles
• rubber gloves
• cotton housecoat or apron (not nylon)
• kitchen scales
• plastic or glass measuring jug
• 2 one-liter heat-resistant glass bowls
• 2 plastic tablespoons (one for the oils and one for the sodium hydroxide solution)
• thermometer (0 to 100°C / 32 - 212°F)
• suitably sized plastic molds
• newspaper

* available from most pharmacies or health food shops
** 1cc is the same as 1ml

Precautions 

Major funding for Rough Science was provided by the National Science Foundation. Corporate funding was provided by Subaru.

Copyright © 2002 The Open University and WETA.