How to render a large number of stacked glass sheets I am trying to render a large number of glass sheets stacked on top of each other (42 to be precise)

I bumped up the transmission bounces amount to 50 just to be sure. set up a simple 'office' environment with some area lights and 3 white walls to have some interesting refractions. I am also using HDRI as a light source.

Is there some general shader that would work well with this kind of setup (stacked glass)? Do i need to worry about different interfaces (Glass to glass, glass to air)? 

See below images for the materials and sample render.

Light paths settings



Material on top side of the glass sheet (as you can see the difference is that i use 'Is transmission ray' instead of 'Is reflection ray', also i add an image with it's alpha as a factor, the image is a mostly transparent png image with some text on it)


Material on sides and bottom of the glass sheet


test render with above settings


I am aiming at maximum realism yet the glass still looks unrealistic and it is "dark" inside no matter how many transmission bounces i use, How can i improve it?

I attached slightly simplified scene so you can see roughly how i proceeded.
FIRSTLY, do you have photo reference? ;-) This render might actually BE really realistic, but your eye is fooled because your brain knows that it's fake. Also, photo reference will help you be specific about what changes to make.

The basic glass and transparent shaders aren't terribly realistic by default. You'll want to look into Physically Based glass shaders. It's a complicated subject, especially for Blender, but essentially you'll build your own shader with a transparent shader, a refraction shader (it doesn't do any reflection), and a glossy shader. You'll put these individual components together with mix shaders, modulating the factor on them with Fresnel or Layer Weight input.

The full details are a bit beyond the scope of this site, but searching for "physically based glass" should get you closer. Also looking at how people have built "fresnel glossy" shaders for Blender will be helpful because the principle is similar.

Here's a helpful link, for as long as it's available: http://www.chocofur.com/6-shadersamptextures.html

It would also be helpful to add a colored checker pattern and/or noise pattern behind and under the glass just for production, so you can see what's going on a little more easily. Then remove it once you get everything right. These stark white, grayscale environments can be very tricky.

Hope that helps!