⇨ Hard Surface sculpting course: https://www.blendersecrets.org Alphas are black and white height maps that can be used as Sculpt brushes in Blender. Normally they need to fit within the circular brush radius. If they have parts that fall outside of this circle, those parts will not be used in the brush. To solve this, go to the texture options of the brush tool panel. Increase the size x and size y values to slightly above 1, for example to 1.1. Now the alpha texture falls within the brush radius. Just don't set the size value too high as that'll shrink the brush. Alternatively, you could set mapping to stencil and then you can use the entire alpha texture as well. But I think that method is more useful for organic models.