There seems to be a little problem with the base material here.,or maybe it’s just that it doesn’t work as I think it should…anyway..
The reflection appears to completely break after tweaking and stays broken.
Here’s a scene with it broken already.The shader itself cannot be altered any more. If you replace it with one that works then it’ll break again.
Other odd stuff happens if you make it metal.
https://www.dropbox.com/s/69k26ez92l…20BUG.max?dl=0
Edit: Weirdly I just tracked the problem down to the refraction ior. If it is set to 1.0 then it breaks. Surely that shouldn’t be linked to reflection?
This was flagged a couple of years ago but not responded to - Chaos Forums
I am not certain I understand what the issue is. Could you post some screencaps illustrating it? Also, which V-Ray version are you using? Otherwise, the refraction IOR is linked to the Reflection IOR by default (click the L button below Fresnel Reflections to disable this behavior).
The point of it all is to have an object and its shadow disappear over time.
The object is reflective. As the object fades, its backfaces are not to be visible.
The file that Svetlozar provided was the one I tested initially. In that scene the material is not reflective, so appears to work just fine.
With a reflective material then the reflections are still there when everything else has disappeared.
I post about this but it remains unreplied to, so I am trying again to make it work properly, if indeed it can work at all.
As the ior parameters are indeed linked, this, as I edited, is the cause of the problem.
I can’t see a workable solution so hope you can 
You can just use the exact same scene to test this. http://ftp.chaosgroup.com/support/scenes/photoshop\_visibility03.max
It is expected for the reflections to remain since they have an IOR of >1, whereas the refraction IOR is 1 (making the object transparent). What may work for your case is using a VRayBlendMtl to separate the reflection and refractions of the shader and keyframe the blending from one the other, syncing it to the refraction increase. Another way is to keyframe the reflection of the shader to decrease parallelly to the refraction increase. See attached scene.
Sure, thanks…I can do hacks to get the effect but was just hoping I’d missed something that would have made it possible without needing to. All good