So, I managed to get a few other parts of this massive terrain undertaking completed tonight. Here are the steps in order:
1) After the build, I rubbed a foam type gap filler putty in the major gaps which were later sanded when it dried.
2) The entire building was given a rough coat of paint. For this I just wanted a fine dusting so I used the Games Workshop stuff, but there are some dashboard paints out there that will really give you some grit.
3) The building and surrounding hill were primed black.
4) The building was painted using the darkest color of rust in my own personal rust paint set. After this, a custom TTG Studio wash was then applied with an airbrush.
5) Resin sand was then mixed with chestnut ink and spread liberally around the rusted bits. Notice the pipes... Again these are Hirst Arts. Cool Stuff.
6) Hairspray was then applied to the building.
7) I got out the airbrush and began to paint the concrete area and the terrain around the building.
The concrete effect is attained by using a type of concrete patch and crack filler(found at Home Depot) spread thinly on top of the foamboard. I used a triad of gray paints to make the contrast from light to dark. A quick wash of TTG Studio "Black" to give it some depth and there we have it. The dirt around the hill will need to be much darker brown for the overall theme of this board which I have decided to make a toxic waste dump. This waste dump has now become a playground for Nurgle. Eventually I will add little nurglings around in some resin pools but for now this is all the time I have had. Let me know what you think!