Freezing areas
By freezing areas of the preview image, you protect those areas from changes. Frozen areas are covered by a mask that you paint using the Freeze tool 
. You can also use an existing mask, selection, or transparency to freeze areas. You can view the mask in the preview image to help you with your distortions.
You can use the icons' pop-up menus in the Mask Options area of the Liquify dialog box to choose how the frozen, or masked, areas of the preview image work (see Using mask options).
Using the Freeze tool
Select the Freeze tool and drag over the area you want to protect. Shift-click to freeze in a straight line between the current point and the previous point that you clicked or Shift-clicked.
Using a selection, mask, or transparency channel
Choose Selection, Layer Mask, Transparency, or Quick Mask from the pop-up menu from one of the five options in the Mask Options area of the dialog box (see Using mask options).
Freezing all thawed areas
Click the Mask All button in the Mask Options area of the dialog box.
Inverting thawed and frozen areas
Click Invert All in the Mask Options area of the dialog box.
Showing or hiding frozen areas
Select or deselect Show Mask in the View Options area of the dialog box.
Changing the color of frozen areas
Choose a color from the Mask Color pop-up menu in the View Options area of the dialog box.