There was a tutorial i saw a while ago about how to RGB texture paint in blender. I kind of got there but im stuck at the point where my soft brush gives me a wierd black alpha border line that mucks up the model. Is there a better way to do this? and yes, i need to mix in about 3 textures to make this work.
That sounds a bit “weird”.. if you use some image and the RGB-channels for mixing between three textures.. then there is no alpha involved 
So you may have to elaborate this to get a more suited answer. Especially about “that one tutorial” from the hundreds of texture mix tutorials which are out there and the shader setup you use (?).
Hi,
Isn’t this what you’re after for: Texture Paint only paints black ?
Also, how to paint objects using multiple textures:
https://youtu.be/opO9ByUaygk?si=XX78iCmbtjMp8X2x