How to make a wall look dirty tutorial?

[tank2002]

Hi all

Does anyone can tell me where i can find a tutorial about making a wall or any surface look dirty?

Thanks in advance

[Alan]

paint the dirt into your texture map, or use a layered shader to a procedural dirt texture on top of the normal wall texture (you could control where the dirt goes with a greyscale painted UV map) :)

Alan

[tank2002]

Thanks pure_morning,

I'm new at this, could you give me details don't know what you mean by procedual dirt texture....create another texture in photoshop that look like dirt? is that what u mean?

thanks inadvance...