I use zip texturing to add a bit of roughness to the usually way-too-smooth surface of the 'ground' on a model railroad. Zip has been around for a long time - I first learned about it in a Kalmbach scenery book by Bill McClanahan written in the '50s.

I use an old Cuisinart blender (not the one we use in the kitchen!) to mix plaster (I use US Gypsum No.1 Casting plaster) with Tempra powder pigment (remember using Tempra paint when you were in grade school?). I use a mix of black and brown Tempra to get a brownish dirt color. Sorry, I don't know the exact amounts of plaster and pigments, I just eyeball it. However, the scenery volume of Joe Fugate's five DVD Siskiyou Line set thouroughly covers zip texturing including measurements.

Application is simple. First mask anything you don't wish to cover with zip powder mud. Then apply water to a small area. Then use a small hand strainer to sift powder onto the water trying for relative even coverage. This works best with a two man crew - one to paint water on the surface, the other to do the sifting.

Paul and Brandon were willing volunteers so while they taped, sprayed, and dusted, I stood back and documented the process.