Lye, chemical formula NaOH, or sodium hydroxide or caustic soda, is used to make soap and biodiesel. Caustic potash, or potassium hydroxide, is also called a lye. As with sodium hydroxide, it can be used to make biodiesel, although the recipe will need to be slightly modified. Unlike caustic soda it can be easily made at home. In this article we will look at how to make potassium hydroxide, or KOH. With potash it is generally not possible to produce solid soap.
Steps
Step 1. Collect rainwater in a barrel
This is a crucial step. Depending on how much lye you want to make, you will need between 7 and 11 liters of water.
- Water from the dehumidifier is fine too.
- You can also use electrically distilled water. The purer the water, the more potash will be extracted from the ashes. Do not use bottled mineral water or tap water without first steam distilling it.
Step 2. Get a wooden barrel and a cork about 7.5cm long
A meter high barrel will do. They can be found on sale in agrarians or in shops specializing in items for beer and wine.
Step 3. Drill a hole in the barrel about 5cm from the bottom
Make sure the cork closes the hole precisely.
Step 4. Place the barrel on a brick base where it does not bother you
Lye is caustic, so take necessary precautions. Create a stable base by placing bricks on the ground and place the barrel on them. The base is used to raise the barrel to be able to empty it easily by placing a container under the cap. Place it in a place where there is room to work.
Step 5. Fill the bottom of the barrel with clean river rocks
Cover the latter with a layer of about 15 cm of straw or hay. This will serve to filter the ash to obtain a clearer lye.
Step 6. Collect some oak, ash, or fruit trees
Remember that the best lye is made from hardwood ash, so avoid pine, fir, and other evergreens. Palm leaves are fine if they are completely dry and brown.
Step 7. Burn the wood, reducing it to ashes
You can make a bonfire outdoors, or in the fireplace or on the stove at home, properly emptied so that the ash does not mix with other substances.
Step 8. Collect the ash and put it in the barrel
Make sure it's cold, or you risk setting fire to the barrel and everything around it. There is no need to fill the barrel with ash.
Step 9. Cover the ash with the water collected earlier
Put a saucepan under the hole and remove the cap. Keep pouring water until you see it starting to seep from the bottom. At this point put the cap back on. After a day the ash will have settled and you can add more.
Step 10. Leave the ash to infuse for at least three days
If you want to use more ash, you can add it regularly by emptying the barrel on a predefined day of the week.
Step 11. Check if the lye is ready
What do you need this lye for? Do you need to make a very strong body soap or cleanser? Concentration increases over time. For saponification, concentration is usually measured by placing a fist-sized potato or fresh egg in the barrel (throw them away later). If it floats about a quarter of its volume above the surface of the water, then it is ready. If not, you will need to add more ash, or drain the barrel and put the water back in with fresh ash.
Step 12. When ready, collect it in a wooden or glass container
Put the container under the hole and remove the cap. Do not fill to the edge, so you can empty it without dripping. Make sure the lid of the container works well.
Step 13. Store the lye in a cool, dark place until you are ready to use it
The sooner you use it, the better.
Advice
- Make sure the barrel is stable and cannot be knocked over by, for example, children.
- To dispose of the spent ash, dig a hole away from your home and pour it in. Do not cover the hole until the ash is completely dry.
- Do not start working until you have collected at least 7-11 liters of rainwater or until you have found enough wood.
- Remember: lye is basic (alkaline), the opposite of an acid.
Warnings
- Keep the lye out of the reach of children, and do not store near flammable materials or metal containers. Lye corrodes some metals.
- The lye is alkaline. Alkaline substances are caustic, that is, they corrode the objects they come in contact with, so use common sense when handling it. If you don't follow the basic safety rules you risk getting very badly hurt, or even dying.
- Learn how to handle a medical emergency before you start using lye. Visit Poison.org to find out what to do in case of accidental contact or ingestion of the lye.
- Hobbyists can use a pair of yellow cooking gloves, safety glasses, and long-sleeved clothing.
- Rinse burns under water. Don't try to neutralize them with vinegar. Alkaline substances can cause deep burns, and you may not immediately notice the severity if your nerves are also damaged.
- In case of need, contact 118 or the emergency number of the poison control center.
