Specular maps export as gray even with roughness at 1 and metallic 0?

[mrmongbat]

https://i.imgur.com/yEj7Pvr.png

Here's a simple way to reproduce the issue I'm running into. A single layer with roughness set to 1 and metallic 0.

Yet when I export the specular map (either through a new preset or for example Unity specular setup preset) the specular map is always grey instead of black. Here's the exported map https://i.imgur.com/8567oif.png

I can't seem to get a blacker specular which causes weird washed out look in Unity when using the substance exported maps.

https://i.imgur.com/8EfSOZV.png (Right example - left is how it should be)

I've tried changing the shader in substance from pbr roughness to various other shaders with no change. I've tried using a level filter, no change.

I'm wondering what I'm doing wrong here?

[mrmongbat]

Seems like I was incorrect, after some research it seems non-metallic specular maps should be rgb 56,56,56 gray. After importing the HDR used in painter into Unity, the material seems a lot closer to what it looked like in Painter.