When you edit or paint weights of smooth skin objects, you sometimes want to specify that the weights of certain objects won’t change. If you’ve perfected the weighting of a particular object, you might want to make sure that its weights are not going to undergo any normalization changes. Maya lets you lock the weights of particular smooth skin objects so that their values don’t change when you are editing other smooth skin objects. See Hold weights

Note that if you lock the weights of many objects at the same time, Maya might not be able to normalize the rest of the weights properly, and you could get an error message. In general, you should not lock the weights of many objects at the same time. Typically, you want to lock the weights of only one or two objects. However, if you don’t want to unlock the weights of any of the objects, you can turn off weight normalization (see Smooth skin weight normalization).