I got the roadbed glued down and all of the road tiles coated with acrylic paste. This was a fairly time consuming process that involves gluing fine ballast o the roadbeds with artist's acrylic matte medium, allowing it to dry, and then "painting" a coat of acrylic paste over the roadbed and on all of the non-road surfaces of the road tiles. The primary materials are shown below.
A coat of acrylic matte medium was painted onto the roadbed, the ballast sprinkled over it, and the excess poured off. Once the matte medium was dry, the terrain looked like this:
I also added more detailing , such as missing retaining walls, more decay to the concrete, etc:
After the matte medium was dry, any loose ballast was brushed/dumped off, cracks in the roadbed where cleared of ballast with a dental pick, and the terrain tiles were coated with acrylic paste. This gives the terrain a milky finish and, locks the ballast in, softens the texture of the ballast, and acts as a primer for the paint.
Next I will add more cracks into the roadbed surface with a Dremel tool, and then begin painting.
Sorry the progress isn't more dynamic, but this is a major step with respect to time before getting on to some of the more interesting work.






