oil (amyl acetate) and all applied in one
coat.

(4) _Stains due to chemical changes_. Certain substances like ammonia,
potassium bichromate, and acetate of iron, give chemical reactions on
certain woods and make very effective and inexpensive stains. Moreover
the artistic effect of some of them is unexcelled. When applied in
solution they are likely to raise the grain.

The effect of ammonia, either the liquid or fumes, is much the same as
the effect produced by aging or weathering. Ammonia also cuts the pith
rays of oak and makes it possible for other stains to take hold.
For this reason it is much used as a preliminary treatment for oak
finishes. The color effect is to lessen the yellow and increase the
gray.

The method of application is simply to expose the wood for a day or
more to the fumes of strong ammonia (28%) in a tightly closed box. If
the surface of the wood is moistened with water just before exposure,
it turns darker than if exposed dry. The stain penetrates so deeply
that it may be sandpapered after the exposure without harm. After
fuming and sandpapering the surface should be oiled to prevent finger
marks.

Dark brown for chestnut, or oak, or mahogany. This is obtained with
a solution of acetate of iron, made as follows: digest one part by
measure of iron dust in 8 parts of glacial acetic acid. After the
chemical action is well started, add several times as much water to
keep the mixture liquid. When the chemical action has ceased, the
stain is ready for use. If a lighter shade is desired it may be still
further diluted.

To darken mahogany. Make a saturate solution of bichromate of potash.
Dilute a portion of it with water 1/2, or 1/3, or 1/4, or in any
proportion according to the darkness required. One part of the
solution to two or three parts of water gives a good color. Apply the
solution to mahogany with a brush. This solution alone is likely to
be too brown. The reddish tinge of the wood may be saved by mixing as
follows:

100% solution of bichromate of potash 1 part
Breinig's mahogany water stain 1 part
Water 2 parts
Apply with a brush and wipe off the surplus.

Bichromate of potash on oak gives a rich brown.

Bichromate of potash on ash gives a rich red.

Bichromate of potash on black walnut gives a dark brown.

A decoction of logwood treated with tannin gives yellow red, with
sugar of lead gives gray brow