Tipskey
Simple Soap Making
It is very easy to make soap. Just three ingredients are needed. Cold process can be used so no cooking is required. Before the wide propaganda of mass-produced soap, people made soap. Homemade soap can biodegrade fast, minimizing the chance of clogged drainage. Homemade soap does not have added harmful additives such as EDTA.

Oil reacts with lye to produce soap and glycerol (also called glycerin). Glycerol is a humectant that can keep skin moist. In mass-produced soap, the glycerol is not present because it has been extracted to be sold away to maximize profit. However, because glycerol attracts water, even a little bit of water in the soap box may cause the soap to become mushy. Let it dry out completely between uses. On way to do this is to place the soap on the bristles of a laundry brush. The bristles should not be dense to minimize surface contact with soap.

This article focuses on coconut oil soap. Coconut oil soap has rich lather and is good in cleaning.

Coconut oil soap with very small lye discount can be used for laundry, dishwashing and handwashing. When coconut oil soap is used for laundry, the clothes may have coconut smell. Some people may not like the smell.

For washing hair, have at least 15% of lye discount so that there is some oil in the soap. It is usually not advisable to use coconut oil soap as body soap because for most people it is too dry for the skin and may cause itchiness. It is better to make olive oil soap for body soap. Compared to coconut oil soap, trace time and curing time of olive oil soap are enormously longer.

soap
Handmade soap.

This process described here is more suited for room temperature of at least 25oC (77oF).

Things to use

Ingredients
  1. Sodium hydroxide. It is also called sodium lye. The chemical formula is NaOH. Pearl type is purer than flake type but both can be used.
  2. Oil in liquid form at room temperature. Even coconut oil can be homemade. Coconut oil can be yellowish or without colour. Both can be used. If heat is used during the extraction process, the oil is yellowish. Virgin coconut oil is colourless and much more expensive so it is better be used for food instead of soap.
  3. Soft water, such as rainwater.
Utensils (corrosion-resistant to lye)
  1. Kitchen weighing scale, preferably with one decimal place for gram.
  2. A container for mixing. It is good if it has a beak (or called spout) for easier pouring of mixture into mold.
  3. Something as a stirrer. It is good to get a rubber scraper (or spatula in American English) because it can also scrape the mixing container when pouring mixture into mold. Electric mixer or blender is not needed because only small quantity of soap is made for self use. Electric mixer will cause the soap to have bubbles. It is good time to burn some calorie by manual stirring. Plus the soap can be called "handmade".
  4. A plastic container to weigh water and to create lye solution. It is safer to have a deep container so that the lye solution cannot splash out accidentally. Do not use glass container that is not heat-resistant because the sudden heat from chemical reaction may break it.
  5. A plastic or glass container to weigh lye.
  6. Molds improvised from "bouncy", non-rigid container in the house such as plastic egg tray, juice carton, business card plastic box. Rigid container makes unmolding less easier. It is easier to unmold from mold made from silicone. For mold not made from silicone, put in plastic sheet as lining to make unmolding easier. Choose mold that is not big so that the soap does not have to be cut into small pieces later. However, The mold to make laundry soap should not be too small so that the application of soap on the clothes will be easier.

Weighing

Pour oil into mixing container until the desired volume. The weight does not have to be exact. Write down the reading of the oil weight.

Use saponification (sap) value to calculate the sodium hydroxide needed. Discount to lye avoids having unsaponified lye in soap. Lye discount is reducing the weight of lye for a certain percentage from the original lye weight. Some call lye discount as superfatting. Soap made with higher lye discount may have shorter shelf life so the soap should be used up soon. For laundry or dishwashing, have 0% lye discount for flake type lye or 1% for pearl type lye. The discount % is personal preference after experiment. If flake type lye is used, the discount % should be adjusted because the purity of flake type lye is already a bit lower.

There are several versions of sodium hydroxide sap value for coconut oil: 0.194, 0.191, 0.19, 0.185, 0.183, 0.182, 0.181, 0.18, 0.178. The variation exists because same type of oil has a range of sap value depending on the other variables such as different breed of coconut. If the purpose of the soap is for laundry or dishwashing, go for 0.191 with 0% lye discount. For body, go for 0.178 plus large lye discount. When the lye discount is more than 20%, the soap will need many more days to harden.

Let's say the soap is intended for body, the weight of the oil is 234 g and the personal preference of lye discount is 15%.
Weight of the lye = [weight of the oil] x [sap value] x [factor after lye discount] = 234 x 0.178 x 0.85 = 35.4 g

Weigh the lye exactly to the calculated value. Be careful with lye as it is caustic. Do not touch lye with bare hand. On skin contact wash with plenty of water immediately.

Close the lid of the lye storage immediately when no more lye is needed. This is because lye is hygroscopic, in which it will absorb moisture from the air and become damp.

Water measurement does not have to be accurate because it is just for dissolving the lye. With too much water, it may be harder to achieve trace during mixing. Mix lye into a little water first. If lye solid is still visible, add water until lye solid is not visible. When adding water, be careful not to pop the solution out of the container.

Mixing

Add sodium hydroxide to water slowly at a well-ventilated area. Exothermic reaction happens. The lye should completely dissolve in water to ensure more thorough mixing with oil later. Wait until the lye solution cools down to room temperature before mixing with oil, which is also at room temperature. If the temperature gap between lye solution and oil is significant, the saponification may be slower or there may be false trace.

Before pouring lye solution into oil, check the lye solution. If some solid is still seen, add a bit more water to dissolve the solid and wait for it to cool again.

It is good to wear a pair of glasses or goggles when stirring the mixture. Pour the lye solution into oil and stir. Do not stop stirring for the first 15 minutes or else the mixture may separate into two layers with oil in the top layer. Listen to a speech in the computer or something while stirring.

trace
Trace.

Stir until the mixture becomes thick enough to show a trace and resistance to stirring, indicating saponification. A trace is a line formed by dribbling from the stirrer on the surface of the mixture that stays visible (see picture). The thicker the mixture, the faster the the soap will harden later. For coconut oil, the trace may appear around a quarter hour to an hour of manual stirring. If after around 15 minutes of stirring the mixture is still watery, to save time just put it aside and stir occasionally while doing other thing.

Pour the mixture into mold. The utensil for mixing does not have to be washed right after pouring the mixture into mold. It is harder to wash at this time because it is still oily. Leave it aside overnight and it will be easier to wash because the soap has been formed. Taking example of 234g oil above, the mixture can fill up three business card boxes.

Unmolding

After 24 hours, check whether the soap has hardened. If yes, the soap can be taken out from the mold. If no, just wait until it is hard enough. Unmolding the soap when it is still soft will affect the shape. Nevertheless, the soap should not be left in the mold when it is already hard enough to be unmolded. This is because its surface needs contact with air to cure.

Final product

Before using the soap, it is best to wait for it to age. The longer the cure time, the milder the soap becomes. For body soap, it can be tested with litmus paper to estimate pH before using. For coconut oil, cure for at least one month. For the soap with large lye discount, if it is still soft after one month, allow more time to harden. It is hard enough if it cannot be dented when pressed by thumb.
Posted: 2015-01-10; updated: 2015-05-08 by Ong Seng Aun.
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