I used a wallpaper scraper and small trowel to level off the grout, and just ran the trowel edge down the semi-set grout.
When very nearly set, i ran a small screwdriver along the rail side then ran an old wagon with deep flanges down just to be sure
I've actually very pleased with how well the grooves came out
I'm delighted with it, I did a section in woodlands smooth it, which looked great too, but a tub of grout from woodies is pre-mixed, cheap, and comes in white, cream, grey and black off the shelf.
Thanks guys, i'm thinking some small puddles with drops of varnish in the cracks, and am going to try the CD cover trick from a recent BRM mag for a large puddle nearer the shed!
Thanks Rich, I've a lot of grubbying up to do, weeds to plant, etc, and have plans to build a back row of half relief stuff over the wall too...
The water tower sets off the corner and the main Shed will be installed just to the right of the three sidings in the second photo..
Goal is something akin to http://eiretrains.com/Photo_Gallery/Railway%20Stations%20N/North%20Wall/IrishRailwayStations.html#NorthWall_20100820_008_CC_JA.jpg