You can make a texture slick or nodamage with a simple shader…
Make a new Shader and edit the path to your Texture.
If you just want have it nodamage…delete the "surfaceparm slick" line!!!

This way is better then making a CUSHION brush over your Floor for example.
Bcz. the cushion Brush is invisible and it looks like you walking in the Air!!!

Quote:

textures/texture_folder_name/nameof_the_texture:q3map { surfaceparm slick surfaceparm nodamage }

TIP: You dont need to make for everything a new Shader.
It is enough if you make one shader for a map with all informations.
Example on another Topic "How Shaders work..."