Creating a cloaking system

I made a very basic stealth system:

Literally, I don’t think it could be any simpler. The only problem I have with it is when I press the F key to swap textures it does so instantly. How would I go about setting up a transition so it takes a second or so to fully transition? I tried making this in C++ and I am running into the same problem, not sure how to keep it from snapping. I thought about a timeline, but it does not seem like timelines support materials.

You can make dissolving material, like here: http://shootertutorial.com/2016/02/20/dissolve-dying-effect/

Awesome! This is exactly what I needed, thanks!