diff --git a/_subsections/chapter04.org b/_subsections/chapter04.org
index 3ee3cdf..290fe03 100644
--- a/_subsections/chapter04.org
+++ b/_subsections/chapter04.org
@@ -62,6 +62,13 @@ while you can certainly delete parts of an image and putting something else in i
    - move the sliders in underlying layer to get what you want
      - if you hold down the ALT key, and hover over the slider, you can split and drag it
 
+** linking and unlinking layer masks
+if you want to move the pattern around, you'll see a problem of the mask moving with the pattern.
+
+this applies to normal transformation
+it also applies even to filters such as blurs.  ie, the blur will affect the shape of the MASK ITSELF
+
+the way to unlink  or unlink is to click on the link icon that connects the mask to the image
 
 * Playlist