Every morning before sunrise, the floor of the house, or wherever the Kolam may be drawn, is cleaned with water and the muddy floor swept well to create an even surface. The kolams are generally drawn while the surface is still damp so the design will hold better. Even powdered white stone (வெங்கசங்கள் பொடி / மொக்குமாவு) can be used for creating Kolam. Occasionally, cow dung is also used to wax the floors. In some cultures, cow dung is believed to have antiseptic properties and hence provides a literal threshold of protection for the home. It also provides contrast with the white powder.
The decoration is not the main purpose of a Kolam. In olden days, kolams were drawn in coarse rice flour, so the ants would not have to walk too far or too long for a meal. The rice powder also invites birds and other small creatures to eat it, thus welcoming other beings into one’s home and everyday life: a daily tribute to harmonious co-existence.
Source: Kolam – Wikipedia