If I set an other refraction color for glass, than I get not a tinted glass, I get a milky glass. It looks like a mix from glass and diffuse material.
Also, everytime if I try to edit my glass material, the diffuse chanal is enable again. I can disable it, close the matiral and open it again - the diffuse is back again.
Refraction color bring a milky effect (build8)
… no answer? Please help. I need a tinted glass. Do I something wrong or is it realy a bug?
Refraction color bring a milky effect (build8)
… I find a way. If I use the fog than it works. I would prefer an other name for “fog”. Why not “absorbtion”. The current name confuse me.
Also I have tested a red refraction color. It bring me an object with a little redish glass and a green-blue diffuse effect at some places. Very strange looking. I think, refraction color means colored glass without absorbtion effect or?
Refraction color bring a milky effect (build8)
Now I have started a simple test with my dummy dino. I find no way to avoid this black areas in the glass. I use HDRI environment, max depth for refl/refrac 12, a big area light and caustic. Also without ground plane the same effect. Nothing helps. What is wrong? Is it a bug? Or is the grey max depth field of the refraction layer the problem/bug.
Refraction color bring a milky effect (build8)
The black is simply the refraction of your hdri I think. Try with a solid white color for environment and see what it looks like.
Fog is indeed absorbtion (=not translucency!!). If you use tinted refr color, it uses no absorbtion if fog is white. Of course you can use both. For glass I always set diffuse fully black, refr color fully white and control all with the fog color. And turn on reflection too, preferably with ‘reflect on back side’ turned on in the options.
Refraction color bring a milky effect (build8)
What are your material settings for that last pic?
Refraction color bring a milky effect (build8)
… default reflection with fresnel and default refraction. Refraction color red. No diffuse.
Refraction color bring a milky effect (build8)
can you post the scene?
sure your diffuse is black?
Refraction color bring a milky effect (build8)
OK, I have catch the bug. 
Everytime if I colose my glass material, the diffuse is internal enabled again. If I open the material, diffuse is back. And per default the diffuse color is grey.
And a diffuse grey color create a green effect, if the glass is red. :shock:
If I set the diffuse black and dosn’t disable it, it works too. But I think, this diffuse-come-back effect must be corrected.
Refraction color bring a milky effect (build8)
I don’t have that diffuse come back effect, make sure you hit ‘apply’ and don’t just clos the material editor.
It’s weird that with grey diffuse and red refraction, your mat turns green. I do have that problem and doesn’t seem to be a correct behavior.
Refraction color bring a milky effect (build8)
I’m sure. Tested it now again.
Refraction color bring a milky effect (build8)
… and what is with the black areas at my dino? Please, don’t forget it, the problem is in a white environment too. 
Here a download for the McNeel test dino:
Refraction color bring a milky effect (build8)
I did some tests, dino is inside a grey sphere and lit with 3 area light that are inside the sphere. Some images look very weird to me, but I’m not sure if it is really wrong or not. The material has no reflection, and almost always ior=1.55.
1. diffuse light grey:
2. diffuse L grey, refraction white (why the black parts?)
3. diff=light grey, refr=light grey
4. diff=orange, refr=light grey
5. diff=dark grey, refr=light grey
6. diff=light grey, refr=dark grey
7. diff=light orange, refr=light grey
8. diff=black, refr= light grey
9. diff=black, refr=white
10. diff=red, refr=white
11. diff=red, refr=very light grey
12. diff= medium grey, refr=light grey, IOR=1.0
13. diff=medium grey, refr=desaturated red, ior=1.55 again
14. diff=light grey, refr=desat red, ior=1.55
Refraction color bring a milky effect (build8)
Also, the cutoff value in options doesn’t seem to have an effect when only refraction is used. Is this normal?
Refraction color bring a milky effect (build8)
My theory, the internal reflections are limited. Do you see the grey field “max depth” = 5. Maybe this option is internal acitve.
Do you mean with your test, you dosn’t get the strange color effect? Try to use an arelight above the dino and set the refraction color to red. I have the feeling, the effect is directed to the light source.
Micha
Refraction color bring a milky effect (build8)
I used are lights with the store with ir map option.
here is a test, white environment color, only default light. Grey diffuse, red refraction color (no reflection). It looks blue. With black diffuse it doesn’t look blue. I assume that you also had grey diffuse in your tests. Or what do you mean by ‘no diffuse’? No diffuse would be black, not grey.
Here a test with GI environment (white), same material. This doesn’t look blue, the darker color is a reddish tint.
Still is weird why the object doesn’t look like a solid color if the environment is totally 1 solid color, and the material has no reflection.
The max depth in material is smth weird, in the globals this option also doesn’t work I as would expect it to.
Refraction color bring a milky effect (build8)
I will post my full test scene tomorrow. Today I will go to bed now.
Refraction color bring a milky effect (build8)
The lights have something to do with the blue stuff:
grey diffuse, red refraction, one area light:
same material, but light is now ‘store with ir map’
Refraction color bring a milky effect (build8)
Here the file and the image from it:
http://www.simulacrum.de/download/Refraction&DiffuseColorBug.3dm
