- How do I keyframe an object assigned material slot?
- How do I keyframe material linked to a material slot? (In the Browse Materials to be linked button just below the materials slots.)
Mixing/Switching Material in the node editor is probably the best solution for you.
- Create two distinct materials. We will switch/fade between these two.
- Create a third material: "mix". Activate nodes for this material (marked red).
- In the node editor, create one material node with the first material and one with the second material. Connect them to a MixRGB node.
- You can animate the material influence with the Factor slider of the MixRGB node in the third material.
- You can still assign the first two materials to other objects.
- You can add more mix nodes in the "mix" material to switch between more materials.
- The material keyframes don't update in the viewport, but will render correctly.