 If you observe prototype track, you'll see it often weathers between the rails differently than elsewhere. To produce this effect on the model, I mixed some dry tempera paint 50-50 with plaster and wiped the grimy color between the rails. Use the dust and grime mix here on the branch. For the sysculine mane I use a blackish mix for the mane and a dirt brown mix for sightings and spurs. Here are the typical formulas I use for my weathering powders. Mainline soot and grease, one part black, one part plaster. Siding dust and grime, one part black, two parts brown, one part yellow, and four parts plaster. Then I fixed the powder in place with a light misting of water. The plaster in the mix will fix the weathering in place once it's been dampened with water and allowed to set up. I clean off the tops of the rails with 600 grit wet dry sandpaper to literally polish the rail heads clean after all the ballasting and weathering work. Finally, I brush the portal with a light tannish gray mix of my plaster weathering powder and mist it with water. The plaster in the mix will make the weathering powder permanent once it dries. My dirty gray weathering powder mix consists of two parts black, one part brown, and six parts plaster of Paris. Once the zip texturing dries, I apply some weathering powder around the portal to blend everything together. I use two colors of weathering powder. Dirty tan, one part black, one part brown, one part yellow, six parts plaster. Dirty gray, two parts black, one part brown, six parts plaster. Once I've applied the weathering powder, I mist the area well with water. Later, after everything has a chance to dry, I come back and check how it looks. Ah, yes! Looks good. The 10 mile creek tunnel portal installation is complete. I use my weathering powders to give the road a look of age by dusting the center areas with a dirty greasy color to represent drippings from cars. I also use a light dust color to further emphasize the ruts. The formula for the dirty greasy color is one part black, one part brown, and four parts plaster. And for the light dust color, two parts brown, one part yellow, nine parts plaster. So, there we go. Our old gravel road is complete. Finally, I come back in and use a special weathering powder mix to blend everything together and give the rock faces a dusty look. I mix some dry powder paint 50-50 with plaster and wipe the grimy color on the rock face. Here are the typical formulas I use for my weathering powders. Soot or dark mildew. One part black, one part plaster of Paris. Dirt and grime. Three parts black, two parts brown, one part yellow, five parts plaster of Paris. Then I fix the powder in place with a light misting of water. The plaster in the mix will fix the weathering in place once it's been dampened with water and allowed to set up. Plus, using the water misting will create subtle water runs down your rock work that simulates the effect of rain and adds that extra bit of outdoor realism to your rock work. Once this dries, I dust on some of my weathering powder mix to blend the rocks and edges of the stream banks into the rest of the scenery terrain. I use some of my dirt and grime mix, which has this formula. Two parts black, one part brown, one part yellow, four parts plaster of Paris. Once I've dusted the rocks and edges of the stream with this weathering powder, I spray it liberally with water to fix it in place. Once the weathering powder has dried completely, I mix black and brown craft acrylics with some of the weathering powder to make a watery stain and flow it along the rocks and banks of the stream to bring out the texture. This final step adds variation to the coloration and removes any of what I call that uniform chocolate ice cream look to the coloring of the rocks and stream banks. Once the terrain and trestle touch up paint has dried, I use a half inch brush to carefully dust on some zip texturing dirt on the new areas, then mist the zip texturing with water. I look for areas where I don't want the zip texturing to be, like on the trestle or on the creek, and I clean them up using damp q-tips. Once the zip texturing dries, I apply some weathering powder around the abutment and trestle vents to blend everything together and mist it well with water. Once it's all dry, I clean up the creek and trestle with damp q-tips. After it all dries, we're done. Ten mile creek trestle is installed.