Kaavi (brick red powder) is applied as an outline, especially on special occasions and pooja days.
In places, where there is a great gathering of people & movement, rice paste made by mixing rice flour with little water is used to apply kolams. This is to ensure that the kolams are not rubbed off easily. This is especially applied in temples & wedding halls. During Krishna Jayanthi, tiny feet symbols are drawn using the rice paste from the entrance of the house leading upto the pooja room, where the sweets made for the occasion are placed. It is assumed that child Lord Krishna walks into each house & partakes of the meal provided.
The month of margazhi (mid Dec) is a gala time for all kolam lovers in the cities and villages. Women start applying huge beautiful kolams very early in the morning undaunted by the chill morning dew. They start learning kolams and make preparations overnight testing the kolam on paper so that they can do a perfect job the next morning. There is a healthy competition in each street, each trying to outdo the others. The current trend is to create colourful rangolis (rang - colour in Hindi) applying colour powders to fill up the white outlines.