Blending Materials on Neighboring Faces

[guynao]

Hello Blenders!

I haven’t been able to find the answer to this question so far, also probably due to the fact that all the keywords that make up this question tend to lead elsewhere.

I have a model, with three different materials applied to different faces of the model.
I was wondering if it’s possible to create a smooth transition between the separate ‘face-sets’, but in a procedural way that will stay intact even if I change one of the materials.

For reference, the model I’m working on is this pencil, but I want the transition between the yellow lacquer and the wooden part to be nicer, and not just look like a hard digital border.

I know smooth transitions can be achieved with a single material setup that has several shaders and transitions through vertex paint, but I feel that this is useful in more organic settings, where the transitions can be fluid.
I need the transition to feel accurate and tight, but nicer than just two faces with different colours. Also I feel like accurately painting the transition in this context will be quite difficult.

Anyway, I’m not sure if this is even possible but I thought it worth a shot to ask the collective mind.

Thanks!

[etn249]

You could use a painted mask, but have your mask be affected by a procedural texture.

You paint a mask with a smooth transition, but then use a math node set to “greater than” so the mask’s borders get slightly shredded by a noise texture:

This setup will create a mask with a hard transition, but with finely detailed borders. As you increase the opacity, more and more of the mask will appear, following the shape of the noise, or whatever texture you choose to use.

The settings of the noise texture will depend on the scale of the scene and your needs.