Separate pattern by Z coordinates I ended up with a kinda cool looking pattern for donut icing.
I've been trying to use it as a mask between two materials (icing and pastry)
The problem I'm facing is that I can't figure out how to get the bottom of the sphere to be black so I can properly use this pattern as a mask. I tried with object and textures coordinates but no luck so far.
Is it even possible or is there a better way to achieve what I'm trying to do ?
Thank you in advance for your help !
The arctan2 into division step is turning this into a radial gradient.  Instead of a light and a dark half you have light and dark quarters of the mesh, basically, and the way you've ramped the color is kind of hiding the problem from you.

So I think what you are asking for is not going to happen without some changes to the math leading up to it.  If you take the output of your noise texture into a math node set to Less Than you may find something you like, or try the following: