Whitewash is a type of white paint that uses calcium hydroxide to turn surfaces white. This paint creates the color by reacting with carbon dioxide in the air, and it then creates a calcite coating. While you can purchase this paint in your local hardware or home improvement store, you can also make your own using simple, easy to find ingredients. Always apply whitewash with a broad brush.
Calcium hydroxide is commonly known as either lime or slaked lime. It is a powder, either white or clear in color. This powder is not toxic, but always wear gloves when handling it in case you are allergic to it. Lime is the main ingredient in whitewash. According to Ask the Builder, lime starts to grow crystals when it hits water. This helps it grab onto other material and stick to it. Another major ingredient is salt. In fact, depending on the whitewash recipe, salt and lime are often the only two ingredients. According to Green Chi Café, one standard recipe for whitewash is 25 pounds of lime mixed with 3 gallons of water and 7.5 lbs of salt with 2.5 gallons of water. According to Ask the Builder, table salt works fine for this process.
According to Ask the Builder, light brown to clear molasses are also used. Molasses is a by-product created during the sugar beet or sugar cane processing process. This by-product is often very thick, and it is commonly used as a preservative. Ask the Builder also recommends that you use unsulfured molasses. Sulfur dioxide is added when you are extracting the sugar from the sugar cane. It acts as a preservative, but it does interfere with the whitewash process.
Alum is a common form of potassium aluminum sulfate, and it is classified as a salt. It is commonly referred to as potash alum. It is soluble in water and is found in baking powder. Alum has a sweet, almost metallic taste. It is often used to purify drinking water and as a skin whitener. In combination with the other ingredients, alum helps to create a really white paint color.
All recipes call for you to dissolve the ingredients in water. Generally, this means hot water, especially when dissolving molasses and lime. Depending on the recipe, you should let your mixture sit for at least 12 hours until it gets the right consistency. If it is too runny, then you can add a cement mixture to make it thicker.