Glass material with opacity mask

Short question about making glass where some areas are “invisible”. I’m making some chemistry equipment and the glass coil for this condenser is hard to figure a good solution for. I suppose real geometry uses too many polys?

Therefore I’ve tried using a simple cylinder with a normal map baked onto it and made a mask from the normal map for opacity. Like this:

In Unreal Engine I’m using the glass material from “StarterContent” and attached the normal map and multiplied the mask with the opacity so the opacity is zero where I want the glass to be invisible. However I have this problem:

As you can see the glass is still not completely invisible (where the red arrows are pointing) even though the opacity is zero, this seems to be because the refraction of the glass still affects it.

Does anyone have any solution to this problem? Thanks a lot for any answers :slight_smile: