You can use it as a topcoat, BUT it will take a looooong time to dry out. The thicker it is the longer it will take to set up....Mike
I only use it for making roads. When I lay out the roads location I stick down some of the fibreglass mesh tape used for drywalling, then smooth it on in thin layers until it is the right thickness, letting it dry between applications. For scenery I would use lightweight Hydrocal to create hardshell scenery and for casting rocks.
It will crack as it dries if you put on more than 1/4" thick at one time. Like Mike says, it's best as a finish coat over Sculptamold, plaster gauze, or similar. I hadn't thought of using it for roads over adhesive-backed joint mesh. Good idea, thanks!
Craigs: I use the 25, 45 or 90 minute dry powder drywall compound that is mixed with water. You have to use what is mixed before it hardens, but the 2nd and 3rd coat can be applied in a short time. It drys hard and is carveable and inexpensive. I add tan paint or brick dye to my mix so that a chip in the future is not apparent. Also the bags are readily available at the local Home Depot, Lowes, etc. Also this material lends itself to ground cover and trees. I have been using it for 20 or more years with good results.
On the two layouts I have built, I used it skimmed over common cardboard as roadways. The technique was from an MR article back in the late 80's to way-early 90's. I could be wrong, but I think it was a Lou Sassi article. Anyway. It works well. And to emphasize what is stated several times above, LIGHT coats. To much, and it cracks as it dries. Here's a shot of one of the roads I built. Joint compound over common cardboard and then airbrushed finish:
I used it thick and thin, always expecting a second or third coat that would fill in the cracks. Cheapest stuff around, so planning for a second coat to fill the cracks on the first coat, or a third for cracks in the second was just ordinary. Joint compound is all I used, for everything. It's heavy and weak--but it is cheap, especially in the 5-gallon bucket. Sometimes the cracks, which form randomly, are part of my scenery.
Maybe. But it wouldn't be thick and you wouldn't be able to move it. Whether "concrete" or "asphalt" depends on how you color it. I just use artist acrylics.
