I'm trying to animate a neon sign that blinks, but I'm having trouble with my materials. Here's the .blend file
I am using the Blender Internal renderer. In order to have a neon sign that blinks I created a material that uses nodes to alternate between two simple materials.
The "Fac" property on the mixes is animated using constant interpolation so it toggles between 0 and 1.
One of the materials (neon phase 2) works just fine. Unfortunately, neon phase 1 (which is the "opposite") does not. When it is off it is not translucent like glass. It is a shiny opaque grey.
What is the critical difference between the two node-based materials that makes one work correctly, and the other be opaque all the time? How do I fix it or work around it?