How to create Mildew on another material in cycles?

Hi all ! :hugs:

First of all : I’m not English or American, so I don’t know if it’s the good word to say it :sweat_smile:

But I would like to know how to create some mildew on concrete, I want to “put it” on another material that I’ve already created, for the mildew, I would like that it’d be looking like this :

(I want only to do the mildew, I don’t want the concrete on the image)

If anyone has some idea to do something who look like this I’ll be glad !!! :laughing:

There are a few ways to do this that I know of.

One method is to use texture paint on a new black and white texture where you want the algae/mildew, and then use this as a mask for the fac input of a mix shader.

The second method is procedural and much the same. You mix two shaders together using the fac input to control where the mould/algae goes, like below. The colour ramp allows finer tuning of how distinct the patches are.

Obviously you’d want to spend more time tweaking the size, colour, bump, etc.

Ok ! I’ll try that right away ! :grin:

sorry it will take time before I test the two option, my computer is laaaaaaggggyyyyy :sweat_smile:

Thks for the solution you’ve give me, but I think this is not perfectly what I want after try it, but I’ve learn things with you’re post and I’m gratefull to you for that !