# weight texture paint on both sides of a plane/face

I am following a beginners tutorial of the famous Doughnut. I came up to the part where particle system is used for the placement of sprinkles on top of the icing and Weight Painting the area of the icing where sprinkles are desired to be. The issue that I have is that, the Weight Paint is applied on both sides of the faces. My guess is that, the icing is made of faces with the Solidify modifier applied.

My question is: How, if possible, can the Weight Paint be applied only on one side, the side I am painting on?

I know the bottom part won't be visible in this case but, I am just wondering in case I come across a scene where the bottom part (faces) are visible as well.

• does your object have thickness? Actually you can move the hair object in Edit mode so that it shifts a bit Commented Nov 29, 2020 at 11:36
• The object (icing) is made up of faces with no thickness. The thickness is added by the solidify modifier. I guess It has to do with the placement of the sprinkles on the faces, since each sprinkle has its origin in the center of mass thus, when used in the particle system, the origin of each sprinkle is placed on top of the icing face which, makes the sprinkles penetrate on both sides of the faces. But still, why the Weight Paint paints on both sides of the faces? @moonboots Commented Nov 29, 2020 at 12:16
• yes, it can be solved by adding thickness but then the question will be, why does the weight paint paints on both sides? Is it possble to paint only on one side? Commented Nov 29, 2020 at 12:19
• with a Solidify modifier, it creates a virtual face that can't be weight painted, so the thickness face inherits the weight paint of the original face, but from what I understand the sprinkles only appear on the top, they just come through the surface because the thickness is not enough, right? Commented Nov 29, 2020 at 12:30
• You can have the sprinkles on both top and bottom faces if you put the Solidify modifier on top of the Particle modifier and enable the Use Modifier Stack option in the Particles settings but I guess it's the opposite of what you want Commented Nov 29, 2020 at 12:45

I was able to fix this by going into the Solidify modifier and select Only Rim. This effectively deletes the part that isn't used (underneath) while keeping the part that is (yummy icing on top). This was done in Blender version 3.0.

Using Blender 3.5.1

1. In weight paint mode press the N hotkey.
2. Go to the Tools tab.
3. Expand the Brush Settings drop down.
4. Expand the Advanced drop down.
5. Check the Front Faces Only checkbox.

• But in order for this to work, you first applied your solidify modifier, right? The question is how to achieve it without applying the modifier. Commented Jun 7, 2023 at 19:46