Stone color is a shade varying very slightly from slate and smoke
color. All light shades can be used for this color; first preparing
them by washing and rinsing them thoroughly. Prepare a medium strong
bath of logwood by boiling for about fifteen minutes; after which enter
your feathers, and let them remain in bath about two or three minutes,
longer if a very dark shade be required; then take them out and rinse
in cold water twice. Prepare a bath of half ounce of bichromate of
potash in one gallon of boiling water, and dissolve thoroughly. Enter
your feathers, and let them remain in bath about two minutes, keeping
them well under the surface of bath and moving at the same time, to
assist in producing an even color; after which take out and rinse off
about three times in cold water, and prepare a bath of hot soap water.
Enter your feathers, and wash thoroughly, adding to bath a small pinch
of soda; after which rinse carefully in hot water; dissolve a small
handful of starch in cold water, pass your feathers through, squeeze
out and dry in the usual way.
If your feathers be found much too light for your sample to be matched,
rinse off starch in cold water, and return your feathers to logwood
bath for a few seconds; dissolve a small pinch of copperas in a
gallon of boiling water, reduce temperature a little and enter your
feathers, letting them remain in bath a few seconds. Take out and pass
through starch and dry. If found to be altogether too dark, dilute a
teaspoonful of oxalic acid in a gallon of hot water; pass feathers
through a few seconds and rinse off in boiling water twice; wash,
starch and dry.