To Colour Brasswork.

Green Shades

Place in a boiling solution of Copper sulphate . . 60 grains Hydrochlorate of ammonia .... 15 Water.....20 ozs.

Red

Chlorate of potash . ;100 grains

Nickel carbonate . ;35 „

Salt of nickel ... ;100 „

Water..... ;20 ozs.

Dark brown

Chlorate of potash . ;150 grains

Salt of nickel ... ;300 „

Water..... ;20 ozs.

White

Orpiment . . . .150 grains

Salammoniac . . . ;300

Water..... ;20 ozs.

Yellow brown

Salt of nickel . . ;150 grains

Copper sulphate . ;150 „

Chlorate of potash . ;150 ,,

Water..... ;20 ozs.

Orange brown. Chlorate of potash . 75 grains Copper sulphate . . 75 grains

Water.....20 ozs.

Blue

Copper sulphate . . ;900 grains

Hyposulphite of soda . ;600 „

Cream of tartar . . ;300 ,,

Water.....20 ozs.

To Blacken

(a) Thoroughly clean the article and dip into a bath (heated) of 50 parts of native copper carbonate dissolved in 1,000 parts of salammoniac, allow the work to remain until the desired colour is obtained. A better black is obtained the more copper is present in the brass.

(b) Take four fluid ozs. of hydrochloric acid, water one fluid oz., ferric chloride one oz. (wt.), and arsenious trichloride 1/2 oz. (wt.), mix in the above order. Dip the articles to be blackened for a maximum of two minutes, remove and rinse thoroughly in water. The surfaces to be blackened must of course be quite smooth and clean, and free from grease. The solution will keep, but is poisonous, but is quite safe to handle, provided the hands are well washed after the job is finished.

(See Vol. 1, page 446.)

Oxidising Brass

In order to oxidise brass so as to give it a black finish use the following solution : 2 oz. of corrosive sublimate dissolved in one quart of vinegar is said to act quickly in blackening copper. This solution is brushed over the brass, it is allowed to remain until the latter is black and it is then wiped off and the brass cleaned and black leaded.

Another receipt is : Make a strong solution of nitrate of silver in one vessel and of nitrate of copper in another. Mix the two together and plunge the brass into the mixture. Remove and heat the brass evenly until the desired degree of dead blackness is obtained.

To give to brass a dull black colour, that used for optical instruments, the metal is cleaned carefully and brushed and covered with a very dilute mixture of neutral nitrate of tin, one part ; chloride of gold, two parts. At the end of ten minutes this covering is removed with a moist brush. If an excess of acid has not been employed, the surface of the metal will be found to be of a fine dull black.

Brass Polishing

Obviously in order to polish a brass surface really well it must first have all imperfections removed. This is generally done by it being held against a leather bob, fine sand being used. In the polishing stage very fine unslaked lime is used on a leather bob, finally it is treated with the lime on a dry calico mop running at a high speed.

For small articles or quantities, a steel burnisher turns out a very good looking job, this burnisher must have a glass-hard surface, as polished and smooth as ever possible, with no corners or edges anywhere. As much pressure is used with it as the operator can supply, with a firm, smooth, rubbing action. A very fine polished-like surface results. Such a burnisher can readily be made out of a worn half round file of convenient size. Grind out all the teeth and marks on a wet grindstone, taking great care not to heat the file during such grinding. After this use emery cloth to get out the grinding marks, using finer and finer emery cloth, until the very finest flour emery can be used on a cloth. The burnisher must finally have a mirror-like surface. All edges and corners of the file should have been well rounded off by the grinding process in the first place.

Testing Brass Articles

Many articles of household brassware on the market, such as candlesticks, vases and so on, are not solid brass, but iron covered over with a thin brass sheeting. By using a small magnet, if there is iron present beneath the brass surface this can easily be found out, and the genuineness of an apparently brass article can often be tested in this simple way.

The magnet will be attracted to any iron or steel present, and a more or less slight pull will be felt depending upon the sizes of the magnet and of the iron or steel. The magnet will not be attracted in the slightest degree by the brass.