When you use a hair styling tool, its operator gets added to the hair object's stack, as you can see in the explorer. You can freeze the hair object's operator stack as you would any object in Softimage (see Freezing the Operator Stack for more information).
Freezing collapses all the styling operators (including any Scale, Rotate, or Translate operators from the Transform panel) into the hair generator operator and keeps the hair's state as the base state.
You can also use the Immediate mode when styling hair, which doesn't keep any operators in the stack. See Immediate Mode.
Freezing the stack lets you style the hair progressively, taking advantage of the dynamics at each new hair state. For example, do some styling, add dynamics and move the hair around to enhance the styling, and then freeze the stack. The results, taking into account the dynamics and any styling operators that are present, are "baked" into a new hair state that becomes the current state. With this new state, you can continue building the style, and dynamics are applied relative to the new hair state.
Below, guide hairs (in white) in a style before freezing.
Character has dynamics applied and is animated to move forward and down quickly. Her hair is frozen in this state to keep it as the current one.
All the styling operators are deleted, including any Scale, Rotate, or Translate operators from the Transform panel as contained in the MoveComponent operator node. If dynamics is applied to the hair, its operator is also removed unless it's muted.
The hair generator operator remains because it is required to generate hair (it is freeze-resistant!).
Also, any points that were locked remain locked even though their Lock operator is removed. This is because the locked state was baked into the base state.
Below on the left, the hair stack with styling operators before freezing.
On the right, the hair stack with styling and dynamics operators gone after freezing. If the dynamics operator is muted when you freeze, it remains in the stack.
