So, i want to know, how can i make things “dirty” the map is of New York and im woking on the china town district, and when i was their, it was dirty, Im currently using white textures, but i want to make dirt, like what you see around a dirty air con but i dont know how, and can i make a puddles in alley ways?

What game are you mapping for?
Find some pictures of what you are trying to achieve and I’ll break it down for you.

Try overlays.

Gmod and

For the walls being dirty you should look around the texture browser until you find some dirty textures that suit you. Also use decals for adding extra dirt to the walls.

For props you can’t really do much. Either the prop is dirty to begin with or you would have to change its texture to make it look dirty - nothing you can do inside hammer.

And what about puddles of water

There are decent urban_puddle models used in both L4D games.

puddles are difficult to make (at least for me).

i would do it by setting your brush to sphere mode and make a 1 unit high body of canal water. it looks good but the problem is that its a really dodgy way of making puddles because its using spheres and can be laggy if set too big.

but thats only if you want puddles that are splashy and realistic.

Search for “puddle” in material browser. Its a decal.

Decals dont work for me.

Try using info_overlay, should work just fine.