Using the write on effects, I'm having trouble keyframing the brush size when 'revealing original image'. Keyframing the brush size does indeed change the size but not only for the desired duration, but instead affects any brush strokes you've already made. Forget the fact that at 2 seconds you stipulated a brush size of 5, if you change the size to 10 at 20 seconds, the 2 second stroke changes size too.
I can't see how this is correct, and totally negates the use of keyframing the size, there MUST be something im doing wrong, and it's not my grasp on keyframes. Anyone have any ideas?