How to colorize (tint) a texture on one side of an object

Question

I want to do this effect, where one face of a column is colorized:

I have added a shader with texture to my object:

What should I do next?

Answer 1

Download grey plaster texture, enable Node Wrangler add-on in Blender settings, select the object, go to Shading tab, select Principled BSDF node and press Ctrl + Shift + T - a Blender File View window should open, navigate to your texture files and select them all. Node Wrangler add-on will now automatically setup your nodes.

The reason why I suggested redoing what you've already did, is that by using not just a color information, but also normals and roughness, you're able to completely remove the texture color, by disconnecting "Base Color" Image Texture > Color from Principled BSDF > Base Color and then override it with a color of your choice:

you can still see the texture of the wall, just like you could see a fat stain on a flat wall with uniform color, because the stain will be more shiny, as well as the normal information fakes depth, which also changes color.

But let's say you want to operate only on the color, you can then use a Hue Saturation Value node to change color information:

This, however, will not work on grey textures and it seems you have a grey texture. You can simply use Mix node to mix two colors - the base color, and a color with which you want to tint. However, in the default, "Mix" mode, the more of your own color you add, the more you "cover" original color, up to a point where at 100% you can no longer see the texture, and you indeed are going for a strong color. Try different modes, e.g. Overlay or Darken, Lighten...

As for limiting the effect to just one side, you could take normal information and convert it to binary 0/1 by using something like Math: less than node:

I added a Math: Multiply node, to have a factor of 90% instead of 100% for the chosen wall.

Let's join all techniques together and we get this:

the blue on the other walls coming from the fact that after applying Displacement, some parts of the geometry now face (roughly) the same direction as our chosen wall. Increase the "threshold" of Math: Greater than to fix that (or just remove the displacement):

Using 100% Mix (an equivalent of disconnecting the node and just setting the color directly in Principled BSDF) instead of 90% Overlay, and very strong Normal Map is probably what you're after:

Keep in mind you could make the process simpler (though more time consuming with many columns) by assigning different material to chosen wall:

Add different materials to different parts of a mesh?

Or make it harder (but less time consuming!) by having one material for all columns, but randomizing the colors:

Cycles Random material with alpha texture

What is the easiest way to have a material randomize the Image textures it uses?