Playing with mud
I finished one of the wheels for the die-cast tractor makeover. The thick factory red paint was difficult to remove, but eventually paint stripper and a final careful sandblasting won out. The glued two piece metal castings fell apart in the stripper. I first added a few dents and dings (as per prototype photos). Then I glued on the plastic hub cap (removed before stripping) and filled the seam with Squadron putty. I masked and painted the hub cap with Floquil Roof Brown spray to serve as an undercoat for chipping (as I plan to do for the few plastic parts). I tried about four (unsuccessful) different paint and application methods before going back to the method I had used on my O scale Fordson (at least my paint jobs stripped off a lot easier than the factory paint!)
I wound up painting each wheel half over the bare metal with 4 coats of water thinned Polly Scale Soo Line Red, waiting about 10 minutes between coats. Shortly after the last coat, I used a dull dental pick (shudder) to chip the paint. I carefully color sanded the paint with 1500 grit sandpaper to smooth the chipped places, and then I dipped the wheels in Blacken-it to darken the exposed base metal areas. After rinsing and drying, I gave each half a coat of spray can Dullcoat to seal the metal and prep the surfaces for powder weathering. The treads were sanded smooth and brushed with Blacken-it. I used wet steel wool to brighten the treads back to dull silver, then I gave them a coat of Model Masters satin spray to protect the metal from tarnishing. I glued the halves back together with thick gel ACC and let them dry overnight.
I began the weathering process by dusting the wheel with a mix of brown Bragdon powders, using a soft brush and an artist’s stump. When satisfied, I began the mud application. I was aiming for a dried/drying type of look, not super fresh mud. I sifted some dirt (the same used on the barn dio) using a fine brass screen. I mixed a small amount of dirt with white glue and water to create a wet paste (the more glue, the darker the dried mud is). I also sprinkled in some jute macramé twine to simulate dried grass. I applied the paste to the spokes and inside rim with an old paint brush. I used a toothpick to apply clumps of mud here and there. I applied the same mixture to the outside rim, but had trouble getting a convincing (to me) look. I had a sudden thought; why not roll the wheel through the mud like the prototype? I calculated the wheel circumference (Pi x diameter) and then cut some proper length styrene strips that were just deeper than the center rib of the wheel. I glued these to a piece of sheet styrene and applied the mud paste to the fixture and rolled the wheel through several times. I liked this result better, and I got some nice dried broken off edges. The mixed-in jute macramé worked well too; many vintage tractor pics I have show grass and such stuck to the muddy wheels. Of course this made the careful prep work to the treads a waste of time, but, oh well. The mud mix is remarkably hardy when dry, and it can be easily removed with water, making do-overs pretty easy. To finish, I stumped on some contrasting brown and tan Bragdon powders around the edges of the mud to simulate fully dried areas.
I went back later and tried applying the mud paste to the rim and then rolling the wheel through the fixture. I got more even coverage that way.
Only three more wheels to go. Sometimes you lead a weathering project; other times you follow. This guy is a lot muddier than I originally planned, but that’s ok, the more the muddier! I’m kind of curious to see just how dirty it’s going to be!