Page 37 of this months (Jan 2020) of the American magazine Model Railroader shows a modeller using what he calls tile grout to create dirt.
Does anyone know what the UK what this stuff is called over here and where to get it ?
A post here says B&Q...
https://www.rmweb.co.uk/community/index.php?/topic/151539-motts-lane-a-foray-into-em/page/6/&tab=comments#comment-4279627
...but I have no idea what this product is called!