Export model without materials? Any way to do it? Or maybe turn materials "off" temporary? The problem I am trying to solve is this: I make a model with different materials only to create a material ID map. If I export it as FBX to Substance Painter, it has several "texture sets" (equal to the number of materials) once loaded in the latter app. That adds an extra step to the workflow: merging maps after export. If I could "turn off" materials before exporting from blender it wold be much easier.

Mind: I obviously can just delete materials before exporting, but I fear that when iterating on some changes I might forget to revert the deleted materials and loose all my data.
Okay, if exporting as Wavefront's .obj file there is a check box "Write materials", unchecking which solves the problem. .obj is widely used and will work in my case.