I currently use anti-fatigue soft compound matting. The 'stipples' that form the natural texture of the surface allow the sole to deposit dust within the 'channels'. The soft nature of the compound itself allows the dust to positively adhere to the mat itself. One can then jet clean outside the darkroom, cleaning the dirt outside rather than simply moving the dirt 'within' the rom. Like anything, it works to a point and is very comfortable under foot too!