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ways called “cold lacquering” and “hot lacquering.” former method the lacquer is applied with a brush as evenly as possible over the article while it is cold; then this is put into an oven, where it is subjected to a gentle heat for about two minutes to set and harden the lacquer; care has to be taken that the oven is not too hot. In the second method the articles are first slightly heated, about as hot as can be borne by the hand; then the lacquer is brushed over them. If the article is small it is put into a hot oven for a minute; if large, there is hardly any necessity for this, as it will keep its heat long enough to set the lacquer.
(a) Pale gold lacquer.–10 ozs. of orange shellac, 1 gallon of spirit, and } oz. of gamboge. (6) Deep gold lacquer.—Orange shellac, 10 ozs. ; turmeric, 4 ozs.; gamboge, 4 ozs.; dragon's blood, i oz.; spirit, & gallon. (c) Pale lacquer.—1 gallon of spirit, 5 ozs. of orange shellac, 4 ozs. of gum sandarac, 1 oz of gum elemi and 1 oz. of gamboge. (d) Brass lacquer.-14 ozs. of shellac, 4 ozs. of turmeric, 1 oz. of annatto, 1 oz. of saffron, and 1 gallon of spirit. (e) Deep lacquer.—10 ozs. of shellac, 6 ozs. of sandarac, 2 ozs. of gum elemi, 2 ozs. of dragon's blood, and 1 gallon of spirit. (f) Gold lacquer.-10 ozs. of shellac, 1 gallon of spirit, and 4 oz. of aniline yellow. (9) Green lacquer.—10 ozs. of shellac, 1 gallon of spirit, and ļoz. of brilliant green. This gives a blue green shade. (1) Green lacquer.-10 ozs. of shellac, 1 gallon of spirit, * oz. of methyl green, and oz. of auramine; this will give a yellowish-green. (i) Bronze green lacquer.—10 ozs. of shellac, 1 gallon of spirit, } oz. of brilliant green, and k oz. of chrysoidine. (j) Blue lacquer.—5 ozs. of shellac, 5 ozs. of sandarac, 2 ozs. of elemi, 1 gallon of spirit, and 1 oz. of alkali blue. (k) Violet lacquer.
—8 ozs. of sandarac, 2 ozs. of shellac, 3 ozs. of elemi, 1 gallon of spirit, and 4 oz. of methyl violet. These examples will serve to show how the coal-tar colours can be used in the preparation of lacquers. A great variety can be thus made by changing the colouring matter used. With some of the so-called aniline colours care should be taken not to use too much, as then the real colour of the dyestuff is not developed but a bronzy green appearance only; this is likely to happen with magenta, the violets and greens. It may also be mentioned that the blues, violets, and some other colours are made in several shades distinguished by letters, as 3R, 2B, 5B, 6G, &c.; in such cases care must be taken as to the particular brand of colour used, for example, there is a great difference in shade between violet 3Rvery red shade—and violet 6B-a very blue shade.
18. Varnish Paints.—These can be made by simply adding colour to any of the varnishes described above. It will, there
fore, scarcely be necessary to give recipes in detail for the preparation of these; a few notes about them and the colours to be used will suffice. This class of varnishes may be classed into two divisions—1st, those which dry with a more or less opaque surface similar to a paint but with the lustre of a varnish; 2nd, those which dry with a transparent lustrous surface. The former, perhaps, may be called varnish paints; the latter, varnish stains. Varnish paints owe their colour to opaque pigments, such as vermilion, Prussian blue, emerald green, chrome yellow, &c. There is no difficulty in making these; simply adding a required colour or pigment in sufficient quantity to any varnish is all that is necessary.
It will be found advisable to use those pigments which are the lightest in weight; heavy pigments like vermilion, red lead, barytes have too much tendency to settle out from the varnish to work satisfactory. Some cheap varnish paints are made from rosin spirit, rosin and pigment. Varnish stains owe their colour to colouring matters which are soluble in the varnish. A great variety of soluble colours, of both natural and artificial origin, can be used for this purpose. “As with the varnish paints any required colour of stain can be obtained by simply adding the necessary colouring matter, which, in this case, must, however, be soluble in the spirit, so that a transparent coloured liquor is obtained. Any of the coal-tar colours soluble in spirit may be used; these have been described above (p. 474); turmeric, annatto, accroides, and other natural colours can also be used.
19. Crystal Varnish.-1 lb. of Canada balsam is dissolved in 1 pint of turps.
20. Gold Varnish.-Shellac, 8 ozs.; sandarac, 8 ozs.; mastic, 8 ozs.; gamboge, 2 ozs.; dragon's blood, 1 oz.; turmeric, 4 ozs.; and spirit, 1 gallon.
21. Black Leather Varnish.—Shellac, 12 ozs.; gum thus, 5 ozs.; sandarac, 2 ozs.; lamp-black, 1 oz.; turpentine, 4 ozs.; and spirit, gallon.
22. Common Red Varnish.—Rosin, 21 lbs.; coal-tar naphtha, 1 gallon; and red oxide of iron sufficient to give the required colour. By substituting other colours for the red, various coloured varnishes may be made.
23. Furniture Varnish.-Shellac, 14 lbs.; sandarac, 4 ozs.; mastic, 4 ozs.; and spirit, 1 gallon.
24. Dammar Varnish.—Dammar, 10 ozs.; sandarac, 5 ozs.; mastic, 1 oz.; and turps, 20 ozs. Digest at a gentle heat until dissolved; if necessary add more turps to bring down to the proper consistency.
25. Black Varnish.--Asphaltum, 1 lb.; wax, 1 oz.; lampblack, 1 oz.; and turps, 2 pints.
26. Common Black Varnish.--Coal-tar pitch, 1 lb.; coal-tar, 2 ozs. ; boiled oil, 2 ozs.; and coal-tar naphtha, 1 gallon. If not black enough, add sufficient lamp-black to bring the colour up.
27. Picture Varnish.--Sandarac, 2 ozs.; mastic, 4 ozs.; copaiba balsam, 1 oz.; gum thus, 3 ozs.; turps, 4 ozs.; and spirit, 3 pints.
ANALYSIS OF SPIRIT VARNISHES.— The analysis of spirit varnishes is somewhat simpler and less difficult than is the analysis of oil varnishes (vide p. 484), still there are difficulties attending it. It is not easy to determine the character of the resins which have been used in the preparation of the sample under examination.
The spirit varnish to be analysed should be placed in a retort and heated to about 230° F. (110° O.), when the whole or nearly the whole of the solvent used will have distilled over; sometimes a higher temperature will be required, but the experience of the analyst will tell him when this is the case.
An examination of the distillate by the usual methods will show its amount and character; of course, alcoholic preparations are those most likely to be met with.
An examination of the residue in the retort will give the analyst some idea of the resins which have been used in the preparation of the varnish under examination, but it is not possible to give any definite tests for different resins.
4th. WATER VARNISHES. This group comprises but few and little used varnishes.
1. Lac Water Varnish.—Shellac, 6 ozs.; borax, 1} ozs.; and water, 1 pint. Boil together until the lac is dissolved. If bleached lac is used a white varnish will be made; if the orange shellac, the varnish will have a pale brown colour. This varnish makes a fair vehicle for water colours; it is a good paper varnish, and dries with a fair lustre and with a hard coat which is waterproof. By adding any of the soluble coal-tar colours coloured varnishes can be made.
2. Glazing Varnish.—Mix 1 pint of white of egg with 1 pint of water. A little carbolic acid or salicylic acid or, better, thymol should be added to preserve this varnish. This varnish or glaze dries with a fair amount of lustre. If, after being applied, it be placed in a hot room to dry, the coat will be made more waterproof. Dried albumen may be used instead of the
white of egg by dissolving 1 oz. in 1 pint of water; only the colour of the glaze is not so good.
3. Glue Varnish is made by dissolving 1 lb. of good pale glue in 2 gallons of water. The colour of this varnish depends very much on the quality of the glue used; if the best gelatine, then a white varnish will be made; if a brown glue, then a brown varnish. This varnish is not very good because of the sticky coat it gives which is not waterproof; by adding just before using, a small quantity of bichromate of potassium (1 oz. in 2 gallons), the coat becomes nearly waterproof. It is important that the bichromate be added only just before use, as it would act on the varnish and cause it to set into a gelatinous unworkable mass.
This varnish forms the basis of some leather varnishes. A little thymol or borax may be added as a preservative,
4. Crystal Water Varnish.—1 lb. of good white gum arabic and 1 lb. of glucose are dissolved in 3 pints of water. This dries hard, with a gloss.
Assay and analysis of pigments, 299.
BARIUM chrome, 141.
Bartlett lead, 51.
assay and analysis, 78.
Basic colours, 464.
Bitumen of Judea, 241, 442.
Black Japan, 481.
lake, 257, 287.
leather varnish, 482.