Flash Layer Mask

A layer mask is like a wall with a window in it. You can not see anything behind the wall, except through the window.

You can animate the mask or the layers beneath it, or both.

A mask is useful for effects and to shape objects


Example 1

Example 2

Example 3

Click here for instruction on to create this mask effect


Creating a Mask  (like example 2 )

The mask can be any shape, as long as it has a solid fill. The shape becomes the "window" that defines what is visible on the layers beneath.

  1. Create a new Movie
  2. Create two layers.
  3. Name the top layer Mask and the bottom Layer Masked Stuff
    It doesn't matter what you call the layers, but its a good idea to name them something descriptive.
  4. On the Masked Stuff layer, draw a whole bunch of stuff. It does not matter what you draw.



  1. On the Masked Stuff Layer, add a keyframe at frame 20 on the
    The Keyframe will make sure the masked stuff shows for 20 frames.

  2. On the Mask Layer, draw a circle on the left side of the screen.
    This object is the mask (mine is purple). It will not show when we are finished, so it doesn't matter what color you make it. It does have to be solid, though.

  3. Make the circle a symbol and animate it so that it moves across the screen in twenty frames.




  1. Right-click the Mask layer-> Choose MASK..

Everything will disappear, except for what we can see through the mask.

  1. Play your movie!


Editing a Mask

You may notice that the mask layer and its sub-layers are locked. The mask layer and its sub-layers must be locked for the mask to function properly.
You must unlock the layers to edit the mask.
You must lock them again for the mask to work.


Quick Step Guide to Masking

  1. Create two layers
  2. On the top layer, draw or place a solid shape. This will become your mask.
    Animate it as you choose.
  3. On the bottom layer place the objects to be masked.
    Remember that none of them will be visible unless the mask shape is directly above it.
    You can animate at will.
  4. Right-click the top layer and choose Mask.

Some other ideas

Example 4:

Text on the Mask layer.  The Mask is the red text.

This is the result:


Example 5:

The blue circle is the mask layer. The circle grows larger in first motion tween, then in the second motion tween the circle grows smaller and flips




Mask Assignment:

Create an animation using a moving mask. As the mask moves across the screen it should reveal your name