diff --git a/_subsections/chapter04.org b/_subsections/chapter04.org
index 290fe03..6710928 100644
--- a/_subsections/chapter04.org
+++ b/_subsections/chapter04.org
@@ -70,6 +70,17 @@ it also applies even to filters such as blurs.  ie, the blur will affect the sha
 
 the way to unlink  or unlink is to click on the link icon that connects the mask to the image
 
+** turning on and off mask
+hold Shift key and click on the mask, a red X will appear on mask
+
+** mask properties: feather
+- bring up properties panel on mask
+  - double click on mask
+  - select mask and click the properties button
+
+- find the feather slider and change it
+
+
 * Playlist
 
 #+ATTR_HTML: :class playlist
@@ -78,10 +89,10 @@ the way to unlink  or unlink is to click on the link icon that connects the mask
 + [[https://youtu.be/aNpO6G72O3w?si=pwKG3NNXzp8NsGN-&t=209][03:29 Why Use A Layer Mask?]]
 + [[https://youtu.be/aNpO6G72O3w?si=D0ZVdRvBZ9jrjm-n&t=227][03:47 Reason 1: Non-Destructive Abilities]]
 + [[https://youtu.be/aNpO6G72O3w?si=w8aLyeLpyyqeX5G9&t=474][07:54 Reason 2: Compatibility with Non-Raster Layer]]
-+ [[https://youtu.be/aNpO6G72O3w?si=cHwwjgjcbIvf3Hno&t=686][11:26 Linking & Unlinking Layer Masks]] *current*
++ [[https://youtu.be/aNpO6G72O3w?si=cHwwjgjcbIvf3Hno&t=686][11:26 Linking & Unlinking Layer Masks]]
 + [[https://youtu.be/aNpO6G72O3w?si=sDBGUsD5CKK_0i1g&t=813][13:33 Turning Off and On]]
 + [[https://youtu.be/aNpO6G72O3w?si=kEM8JPCox3RhIuSq&t=868][14:28 Mask Properties: Feather]]
-+ [[https://youtu.be/aNpO6G72O3w?si=G6x177vUaa4TxX4Y&t=1062][17:41 Mask Properties: Density]]
++ [[https://youtu.be/aNpO6G72O3w?si=G6x177vUaa4TxX4Y&t=1062][17:41 Mask Properties: Density]] *current*
 + [[https://youtu.be/aNpO6G72O3w?si=BIUkibJYNuT6ivq8&t=1184][19:44 Duplicate Masks]]
 + [[https://youtu.be/aNpO6G72O3w?si=X85qg0vdXugnBIR2&t=1295][21:35 Problem with Copying Masks]]
 + [[https://youtu.be/aNpO6G72O3w?si=2EubEOKmDI9dETuQ&t=1417][23:37 Double Masking]]