I wrote an article that was published in the March 2005 Railroad Model Craftsman. This is the original article, it is longer. The article was shortend and somethings were garbled. It was re-titled "California's golden grass". This is the complete article.
My Pacific Coast Air Line Railway is an On30 model railroad loosely based on the central California Pacific Coast Railway. Central California scenery is mostly grass. All but a few weeks a year the grass is a dead brownish-yellow. Initial thought was to model the grass as green, green would be easier to model with the available materials. I have 320 feet of benchwork planned so a method had to be economical and produced reasonably quickly.
I went to the National Narrow Gauge convention in Santa Clara. Paul Scoles had a clinic and mentioned faux fur grass. He painted the fur with thinned latex paint. Gleefully I tried this method. It was a mess. There have been other methods discussed. Spray painting the faux fur in place proves messy. Railroad Model Craftsman had an article in the '80's about wire brushing felt.
I was "googling" on the Internet for dyeing acrylic for some time with no results. Analine dye came up but that is too toxic. One night something new came up on the "google", a product called Dye-na-flow by Jacquard. I found a Starter pack, an Exciter Pack by the manufacturer. I went to Joann Fabrics and Walmart and found faux fur. Early experimentation produced viable results. California dry grass could be produced.
High grass was my first objective. More would come of this venture than expected. Several new techniques developed.
I found this at Joann Fabrics. It is called "Grizzly Fur". It makes a good backtround high grass. The fibers are about three inches long and must be trimmed.
This is another fur I found. It does not make good dead grass. The fur fibers must be wispy. The fibers in this faux fur tend to stick together. They are too long for green grass and too thick when trimmed. Sugar cane might be a use.
This is Dye-na-flow. It isn't really a dye but a very strong-pigmented thin acrylic paint. The "Brass" color is the basis for dead grass. Other colors that are useful are "Brown" and "Golden Yellow". They have a wide spectrum of colors to experiment. It is available in four sizes 2.5, 8, 32 ounces and gallons. I get mine mail order from Dharma Trading Company. Dick Blick also has Dye-na-flow.
Tall grass requires the following:
Iron - a cheap one the dye collects on the heated surface
Hair dryer - a high power one, 1875 watts
Small scrub brush - a nail brush or grime buster
Beard trimmer - the grass must be mowed, scissors are too slow and hair clippers don't work.
Not shown is a small comb and large disposable foil broiler pans.
Containers to hold the solution
2 Small basters to transfer the Dye-na-flow
Graduated measuring cup
The fur is prepared in a large disposable roasting pan to contain the mess. Cut a piece to fit in the pan.
The fur is shaved with the beard trimmer until the desired height is reached. I make mine about three eighths to a half inch high.
The fur can be cut with scissors by rolling it around a full paper towel roll. The hair is fluffed up as the fur is rolled and is clipped off. Just keep rolling the fur around the towel roll .
"Brass" Dye-na-flow is mixed with water. The water to dye ratio controls the color intensity. A mixture of ten parts water to one part dye is a good starting mixture for tall grass. Lighter grass can be made using a mixture with more water and darker with more dye. The fur can be re-dyed to darken. Pour the mixture over the fur in the pan. Saturate the fur completely with dye.
Wring the excess dye from the fur and pour it back in the container. Wear rubber gloves if you don't want green cuticles.
Take the stiff brush and brush the dye through the fur. Go both directions twice. Finally brush the fur in one direction.
Ironing is the key step in the process. It took me a month to find this key. Place the pelt on a piece of clean cardboard. Set the iron to the highest setting. Go over the fur about five times with the iron, the water from the dye solution should steam off. The pelt should be wet or the iron will melt the fibers. Flatten the fur out. The iron "sets" the dye on the fur fibers. My early efforts required scrubbing for almost an hour.
The fur looks like this after ironing. The dark specks are burnt dye from the iron. They don't affect the outcome.
Blow-dry the fur. Blow-dry both sides. The fur will be fluffy.
Comb the fur to eliminate the bunched areas. Areas that have too much dye pigment bunch together forming nits. Separate them. The nits add texture and look like another growth in the field.
The fur should look like this. Walk paths can be put in the grass.
Faux fur only trims with a beard trimmer. The Wahl 9918 is the best. It is corded so is always ready. Hair clippers will not work.