Under this heading should be classed bronze, bottle, olive and Quaker green that appear in oil color lists, issued by some color grinders. Foremost among these is bronze green, which at the present day, however, is misnamed, as the colors labeled bronze green as a rule resemble either bottle green or olive green. True bronze green was all the rage for store fronts and trimmings during the seventies of the last century and at the Centennial Exhibition at Philadelphia in 1876, the wooden portions of every exhibit and show case were painted with such a green, striped with gold. The effect of this green was nearly black, with a faint tinge of green, when viewed in the shade or absence of strong light, but giving a distinct bronze glimmer in the sunlight. This effect could not be produced, except by mixing a good drop black and chrome yellow of the proper shade.
Very good and lasting results were obtained by mixing and grinding together forty-three pounds powdered drop black (pure bone black), three pounds powdered litharge, five pounds medium chrome yellow, three pounds orange chrome and forty-six pounds fire boiled manganese oil. The latter was used to insure drying as a combination of bone black and chrome yellow retard the drying of oil to quite an extent. We may as well state right here that a bronze green of that character will not find much favor among the trade to-day, at least not as an oil color in paste form.
The trend of the time is to have a dark bronze green of a color similar to what used to be known as bottle green, with a blueish cast, while for a light bronze green the olive green effect is favored, with this exception that in either case white must be absent. When the very small difference in the price, as given in the lists is considered, it stands to reason that the bronze greens listed are not chemically pure in their pigment portions, although they can be so made if consumers will pay the price for the goods. A very pretty shade of dark bronze green from pure pigment colors can be made in paste form in oil as follows: -
Fifteen pounds lemon chrome yellow, ten pounds dark chemically pure chrome green, thirty-five pounds ivory (bone) black, thirty-six pounds raw linseed oil, four pounds oil drier. For a light shade, mix and grind thirty-five pounds lemon yellow, fifteen pounds medium chemically pure chrome green, twenty pounds ivory (bone) black, thirty-two pounds raw linseed oil and three pounds oil drier. These formulas produce pastes that can be extended with any reasonable quantity of fine barytes, which addition, while taking away a portion of bulk and spreading quality, will not materially affect richness of tone. If the greens are ground fine in the above composition, the dry barytes may be added in the change can mixer with sufficient extra oil to make the paste smooth, and for ordinary purposes it is unnecessary to return it to the mill. This method will save the grinding of a lot of extending pigments. Of course these may also be mixed and ground with the coloring matter from start to finish and in that case a mill of large diameter will produce a large output when well handled. When clearness of tone is not so much of an object as low cost and good covering, working, etc., ivory (bone) black may be omitted and gas carbon black used in its place. On account of the great tinting power of the latter, the percentage must be rather small in comparison with bone black. A typical formula for a bronze green of fair quality for ordinary painting, ground in paste form for the trade, would be about as follows: - Nine pounds light chrome yellow, seven pounds chemically pure chrome green, dark; three pounds carbon black, twenty-eight pounds barytes, twenty-eight pounds Paris white, and twenty-five pounds raw linseed oil - total, 100 pounds. If well ground this green will not settle in the container and will keep in sealed packages for a long time. If ordinary lampblack is substituted in the above formula for carbon black, a lighter shade of a duller tone will be produced that will pass for Quaker green.
For a good bottle green, which must be of a more blueish green tone to deserve that name, the coloring matter should consist of bone black, dark chrome green of the blueish type, with a small percentage of white, preferably zinc oxide. Twenty-five pounds bone black, powdered; ten pounds chemically pure chrome green, deep; two pounds Prussian blue, three pounds zinc oxide, thirty pounds fine barytes, mixed with thirty pounds raw linseed oil will make 100 pounds of a bottle green in paste form, that will cover well on one coat of lead colored primer and will hold its color. For a bottle green in a chemically pure form, figure on thirty-seven and one-half pounds dry bone black, powdered; fifteen pounds chemically pure chrome green, dark; three pounds Prussian blue, four and one-half pounds zinc oxide mixed with forty pounds raw linseed oil or thirty-five pounds raw linseed oil and five pounds good oil drier. This will be an excellent paste for covering and wear and its cost will not be prohibitive.
Olive green is not found in the oil color lists of color grinders, but they are often called upon to produce such green in paste form, where the consumers or painters desire to do their own thinning. When wanted for exterior woodwork, it may be made from French yellow ocher, chrome green, red and black, with some white. This type is least costly, even when extenders are not used in its make-up. Fifty-five pounds French yellow ocher, three pounds grinders' lampblack, five pounds white lead, two pounds Venetian red, five pounds chemically pure chrome green, medium or dark, all dry, mixed with thirty pounds raw linseed oil, will produce a green of the olive type in good paste form for the purpose named.
When olive green paste in oil is desired for the purpose of using it as a base for a dipping paint for metal, where the paint is to dry flat, yellow ocher must not be used as a constituent, as it is apt to work too puffy. The following will be found a good paste base that will not settle to any extent when thinned with pure turpentine in the proper proportion for dipping: - Six pounds grinders' lampblack, twenty pounds zinc oxide, five pounds red oxide, four pounds medium chrome yellow, thirty pounds chemically pure chrome green, medium, mixed with twenty-eight pounds raw or boiled linseed oil and nine pounds japan drier of approved quality. This will produce 100 pounds of finished paste of a good medium olive green shade. The paste, of course, must be ground very fine in order to avoid an appearance of grit or roughness on the dipped metal, especially when it is to be finished with varnish after having dried. We do not propose to furnish a number of mixing formulas for composite greens in paste form, as these are too numerous and must be made up specially to suit the requirements of the consumer.