Dilute some gray and

Dilute some gray and black paint at say 1 drop of paint to 10 drops of thinner. That's a wash. If you're working with wood, I'd use a solvent based paint. Acrylics and especially the water will curl your wood. You could also put some black india ink in some denatured alcohol for a black wash. Play with the amount of color in the diluting medium, and write down the ratios you like. Helps to reproduce your work.

Or you could pick up some Minwax stains in your desired colors. Don't stir the pigments up. Use the liquid sitting on top.

Another option is to go to an art supply store and look at their felt-tip pens in the various artist colors. There are ranges of warm (redder) & cool (bluer) grays, along with a lot of red/brown/orange colors. I picked that up from an article years back in the Narrow Gauge Gazette.

Good luck.

Ken O'Brien

Gray weathered wood

Senilecitizen,

What I have found to weather wood to look old and grey. First, I thin down some white acrylic paint with water until it is the consistency of heavy cream and paint the surface I want to weather. After this is dry I take India ink and alcohol mix and paint this on over the white paint. This is used as a wash applied with a medium sized paint brush. I do this as many times as needed to get the degree of weathering I want. Here is a web site that describes these techniques. http://www.pacificcoastairlinerr.com/weathered_wood/ It works for me and when done correctly is very convincing.

Try denatured alcohol, black, white and brown inks

I've had a lot of success using Pelican inks (black, white and brown) in denatured alcohol.  This mix gives meduim to light grays.  I did an article in the old Mainline Modeler years ago on finishing an AMB wood store using this method.  make sure you stain both sides of a large piece of wood or it will warp.   

Charlie