Whitewash, a mixture of lime, water and salt, as well as color additives such as chalk, molasses, blood, egg white and milk, was first used in the mid 19th century in household and farm exterior maintenance. As paint's predecessor, it first offered itself as both a means to beautification as well as sanitation. It can be inexpensively purchased or easily made, and offers many modern modes of application.
Whitewash, also known as calcomine, is an inexpensive type of paint made from slaked lime, salt, and chalk. When these two substances mix with the atmosphere, carbonation, a chemical reaction, occurs.
Whitewash was originally used in routine barn maintenance in the mid-1800's to smooth rough spots and, over time, remove dust and sediment as the whitewash flaked off.
Not only did whitewashing maintain the coated surfaces, but it also added an exterior attractiveness to buildings. Pigmented paints had not yet reached consumers and whitewash, at its incredibly inexpensive cost, could be painted liberally on any fence, barn or gate. Its uses are still applicable in the 21st century, used in home decoration and desired for its "neat, clean feel."
Because whitewash is thinner and more watery than normal paint, it tends to run, as washing something might, so make sure you have a drop cloth. It spreads easily and lightly onto walls, so be sure not to goop it on.
You can purchase ready made whitewash mix or you can make your own. A typical recipe calls for a 50-pound bag of hydrated lime and a 10-pound bag of salt. Add water until the desired consistency is obtained and add chalk for color. Other additives, such as molasses or potash, are often used.