How it's actually done ?

focus_method

Hello,
Is it possible to have two different materials on the one single object  separated by uvs? (if it works like that)
 For example if I have a creature or human character with mouth opened, I assume inner mouth should be made with one material and outter mouth with other material (human skin material or SSS) fort the skin ,lips ?
can all this be done in vray for max ?
substance painter?
mari ?

focus_method

example number 2:

if i have a creature...on the top of the skin at some parts i want it to be bloody , how do you do that ? 
because it's kinda two different materials right ? you have dry skin and that bloody part is liquid right ? it needs more glossines etc. but it's all part of the one mesh.

oglu

Yes and Yes and Yes. All you describled could be done and is a valid worklfow.

Obscura

Yep. Just assign separated materials to the polygons that you want to have different material. Then uv according. Its a fully common practice.

oglu

For Blood on top just paint them in Substance or simulate a fluid on top. 
But simulated blood is no fun. I tried that several times.

oglu

Warning Blood inside. Substance Painter Blood Brush.
https://www.youtube.com/watch?v=5nIBzfcNZhY