We've had three sets of these now and two have been returned (to John Lewis) because they ran out so quickly. It can't be right that during one painting session (of less than one and a half hours) by my three year old, one of the brushes ran dry, followed quickly by another! The second set lasted only slightly longer. Aside from that they are excellent - no mess, and even young children can draw very fine lines. But if our experience regarding the length of time that they last is correct, then they are far too expensive for general use.