Once you have mixed the powder with water, it can be kept for one year in an airtight container. In powder form, it can be kept for years.  Kalkpaint leftovers are ideal for painting flowerpots such as terracotta, and can be applied directly on the surface, allowing the pot to breathe naturally or other items. If you have enough, It can also be kept to freshen up your wall with a new layer later on.