Exporting / importing .obj messes up the materials I have a problem. If I export the model with blender materials in to .obj format, and then import it back,all the materials persist, but are much darker then the original exported ones. 

(left - original, right - import)



The thing is that there is a transparency property added, and all specular changed to black, as well as base colour darkened a bit. Also mirror property is set to 100%, and mirror colour to black.

What is wrong with this? Any way to fix it?
You cannot avoid some changes, simply because .OBJ (.MTL actually) shading model is not exactly the same as BI one (not talking about nodes here, if it’s relatively easy to import .mtl as a basic nodal shader, the reverse operation is practically impossible and hence not supported).

That said, several issues here were fixed in past months (regarding mutual influences between world and material especially), so suggest you try with the latest build from our buildbot, if not yet done. :)