How to remove that strange facture

Are you on Mac? I am experiencing it too. When I played on Windows I didn't notice it.

Doh! I should have looked at the toolbar lol.

This is actually intended, although we need some more appropriate textures for this "grain effect" on wood and other smooth surfaces.
However, the easiest way to get rid of the "grain" would be to use a texture pack and replace the texture which is responsible for this. I prepared a texturepack for you, to use it, simply move the zip file (do not extract it) into the "Texturepacks" folder in your game directory (Steamversion: to get there, rightclick on rw in steam -> properties -> local files -> browse local files). If there is no such folder, create it. Now return to the game directory, open the "config.properties" file and change the line custom_texturepack= to custom_texturepack=NoGrain.zip. Save the file, and run the game. The grain effect should be gone now