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Another (Drying quality may be)

A drying quality may be communicated to oil by treating, in a heat capable of maintaining a slight ebullition, linseed or nut-oil, to each pound of which is added 3 oz. litharge, reduced to fine powder.

The preparation of floor-cloths, and all paintings of large figures or ornaments, in which argillaceous colors, such as yellow and red boles, Dutch pink, etc. are employed, require this kind of preparation, that the desiccation may not be too slow; but painting for which metallic oxides are used, such as preparations of lead, copper, etc., require only the doses before indicated, because these oxides contain a great deal of oxygen, and the oil, by their contact, acquires more of a drying quality.

Another. Take of nut-oil, 2 lbs.; common water, 3 do.; sulphate of zinc, 2 oz.

Mix these matters, and subject them to a slight ebullition, till little water remains. Decant the oil, which will pass over with a small quantity of water, and separate the latter by means of a funnel. The oil remains nebulous for some time; after which it becomes clear, and seems to be very little colored.

Another. Take of nut-oil, or linseed-oil, 6 lbs.; common water, 4 lbs.; sulphate of zinc, 1 oz.; garlic, 1 head.

Mix these matters in a large iron or copper pan; then place them over the fire, and maintain the mixture in a state of ebullition during the whole day. Boiling water must from time to time be added, to make up for the loss of that by evaporation. The garlic will assume a brown appearance. Take the pan from the fire, and having which will clarify itself in the vessel. By this suffered a deposit to be formed, decant the oil, colored. It is reserved for delicate colors. process the drying oil is rendered somewhat more Preparation of a Drying Oil for Zinc Paint.

In order to avoid the use of oxide of lead in making drying oil for zine paint, oxide of manganese has been proposed as a substitute. The process to be adopted is as follows: The manganese is broken into pieces about the size of peas, dried, and the powder separated by means of a sieve. The fragments are then to be introduced into a bag made of iron-wire gauze.

This is hung in the oil contained in an iron or copper vessel, and the whole heated gently for 24 or 36 hours. The oil must not be allowed to boil, in which case there is great danger of its running over. When the oil has acquired a reddish color, it is to be poured into an appropriate vessel to clear.

For 100 parts of oil 10 of oxide of manganese may be employed, which will serve for several operations when freshly broken and the dust separated. Experience has shown, that when fresh oxide of manganese is used it is better to introduce it into the oil upon the second day. The process likewise occupies a longer time with the fresh oxide. Very great care is requisite in this operation to prevent accident, and one of the principal points to be observed is that the oil is not overheated. If the boiling should render the oil too thick, this may be remedied by an addition of turpentine after it has thoroughly cooled.

On the Manufacture of Drying Linseed Oil without Heat.

When linseed-oil is carefully agitated with vinmixture allowed to clear by settling, a copious egar of lead (tribasic acetate of lead), and the white, cloudy precipitate forms, containing oxide of lead, whilst the raw oil is converted into a drying oil of a pale-straw color, forming an excellent perfectly in 24 hours. It contains from 4 to 5 per varnish, which, when applied in thin layers, dries cent. of oxide of lead in solution. The following proportions appear to be the most advantagecus for its preparation: oz. of neutral acetate of lead are placed, and when In a bottle containing 44 pts. of rain-water, 18 the solution is complete, 18 oz. of litharge in a very fine powder are added; the whole is then allowed to stand in a moderately warm place, frequently agitating it to assist the solution of the litharge. This solution may be considered as complete when no more small scales are apparent. The deposit of a shining white color (sexbasic acetate of lead may be separated by filtration. This con- | may be added. The latter liquor is a regulator version of the neutral acetate of lead into vinegar for the consistence in the hands of an artist. of lead, by means of litharge and water, is effected in about a quarter of an hour, if the mixture be heated to ebullition. When heat is not applied, the process will usually take 3 or 4 days. The solution of vinegar of lead, or tribasic acetate of lead, thus formed, is sufficient for the preparation of 22 lbs. of drying oil. For this purpose the solution is diluted with an equal volume of rain-water, and to it is gradually added, with constant agitation, 22 lbs. of oil, with which 18 oz. of litharge have previously been mixed.

When the points of contact between the lead solution and the oil have been frequently renewed by agitation of the mixture 3 or 4 times a day, and the mixture allowed to settle in a warm place, the limpid straw-colored oil rises to the surface, leaving a copious white deposit. The watery solution, rendered clear by filtration, contains intact all the acetate of lead at first employed, and may be used in the next operation, after the addition to it as before, of 18 oz. of litharge.

By filtration through paper or cotton, the oil may be obtained as limpid as water, and by exposure to the light of the sun it may also be bleached.

Should a drying oil be required absolutely free from lead, it may be obtained by the addition of dilute sulphuric acid to the above, when, on being allowed to stand, a deposit of sulphate of lead will take place, and the clear oil may be obtained free from all trace of lead.

Resinous Drying Oil.

Take 10 lbs. of drying nut-oil, if the paint is destined for external articles, or 10 lbs. of drying linseed-oil if for internal; resin, 3 lbs.; turpentine, 6 oz. Cause the resin to dissolve the oil by means of a gentle heat. When dissolved and incorporated with the oil, add the turpentine; leave the varnish at rest, by which means it will often deposit portions of resin and other impurities; and then preserve it in wide-mouthed bottles. It must be used fresh; when suffered to grow old it abandons some of its resin. If this resinous oil assumes too much consistence, dilute it with a little essence, if intended for articles sheltered from the sun, or with oil of poppies.

Fat Copal Varnish.

Take picked copal, 16 oz.; prepared linseed oil, or oil of poppies, 8 oz.; essence of turpentine, 16 oz.

Liquefy the copal in a matrass over a common fire, and then add the linseed oil, or oil of poppies, in a state of ebullition; when these matters are incorporated, take the matrass from the fire, stir the matter till the greatest heat is subsided, and then add the essence of turpentine warm. Strain the whole, while still warm, through a piece of linen, and put the varnish into a wide-mouthed bottle. Time contributes towards its clarification, and in this manner it acquires a better quality. shell.

Varnish for Watch Cases in Imitation of Tortoise- Take copal of an amber color, 6 oz.; Venice turpentine, 1½ oz.; prepared linseed-oil, 24 oz.; essence of turpentine, 6 oz.

It is customary to place the turpentine over the copal, reduced to small fragments, in the bottom of an earthen or metal vessel, or in a matrass exposed to such a heat as to liquefy the copal; but it is more advantageous to liquefy the latter alone, to add the oil in a state of ebullition, then the turpentine liquefied, and in the last place the essence. If the varnish is too thick, some essence Gold-colored Copal Varnish.

Take copal in powder, 1 oz.; essential oil of lavender, 2 oz.; essence of turpentine, 6 oz.

Put the essential oil of lavender into a matrass of a proper size, placed on a sand-bath heated gently. Add to the oil while very warm, and at several times, the copal powder, and stir the mixture with a stick of white wood rounded at the end. When the copal has entirely disappeared, add at three different times the essence almost in a state of ebullition, and keep continually stirring the mixture. When the solution is completed, the result will be a varnish of a gold-color, exceedingly durable and brilliant. Another Method.

To obtain this varnish colorless, it will be proper to rectify the essence of the shops, which is often highly colored, and to give it the necessary density by exposure to the sun in bottles closed with cork stoppers, leaving an interval of some inches between the stopper and the surface of the liquid. A few months are thus sufficient to communicate to it the required qualities. Besides, essence of the shops is rarely possessed of that state of consistence without having at the same time a strong amber color.

The varnish resulting from the solution of copal in oil of turpentine, brought to such a state as to produce the maximum of solution, is exceedingly durable and brilliant. It resists the shock of hard bodies much better than the enamel of toys, which often becomes scratched and whitened by the impression of repeated friction; it is susceptible also of a fine polish. It is applied with the greatest success to philosophical instruments, and the paintings with which vessels and other utensils of metal are decorated.

Camphorated Copal Varnish.

This varnish is destined for articles which require durability, pliableness, and transparency. Take of pulverized copal, 2 oz.; essential oil of lavender, 6 oz.; camphor, & oz.; essence of turpentine, a sufficient quantity, according to the consistence required to be given to the varnish .

Put into a phial of thin glass, or into a small matrass, the essential oil of lavender and the camphor, and place the mixture on a moderately open fire, to bring the oil and the camphor to a slight state of ebullition; then add the copal powder in small portions, which must be renewed as they disappear in the liquid. Favor the solution, by continually stirring with a stick of white wood; and when the copal is incorporated with the oil, add the essence of turpentine boiling; but care must be taken to pour in, at first, only a small portion.

This varnish is a little colored, and by rest it acquires a transparency which, united to the solidity observed in almost every kind of copal varnish, renders it fit to be applied with great success in many cases.

Ethereal Copal Varnish.

Take of amberry copal, oz.; ether, 2 oz.

Reduce the copal to a very fine powder, and introduce it by small portions into the flask which contains the ether; close the flask with a glass or a cork stopper, and having shaken the mixture for an hour, leave it at rest till the next morning.

In shaking the flask, if the sides become covered with small undulations, and if the liquor be not exceedingly clear, the solution is not complete.

In this case add a little ether, and leave the mixture at rest. The varnish is of a white lemoncolor. The largest quantity of copal united to ether may be a fourth, and the least a fifth. The use of copal varnish made with ether seems, by the expense attending it, to be confined to repairing those accidents which frequently happen to the enamel of toys, as it will supply the place of glass to the colored varnishes employed for mending fractures, or to restoring the smooth surface of paintings which have been cracked and shattered.

The great volatility of ether, and in particular its high price, do not allow the application of this varnish to be recommended, but for the purposes here indicated. It has been applied to wood with complete success, and the glazing it produced unites lustre to solidity. In consequence of the too speedy evaporation of the liquid, it often boils under the brush. Its evaporation, however, may be retarded, by spreading over the wood a light stratum of essential oil of rosemary or lavender, or even of turpentine, which may afterwards be removed by a piece of linen rag; what remains is sufficient to retard the evaporation of the ether.

Fat Amber or Copal Varnish.

Take of amber or copal of one fusion, 4 oz.; essence of turpentine, drying linseed oil, of each, 10 oz.

Put the whole into a pretty large matrass, and expose it to the heat of a balneum mariæ, or move it over the surface of an uncovered chafing-dish, but without flame, and at the distance from it of 2 or 3 inches. When the solution is completed, add still a little copal or amber to saturate the liquid; then pour the whole on a filter prepared with cotton, and leave it to clarify by rest. If the varnish is too thick, add a little warm essence to prevent the separation of any of the amber.

This varnish is colored, but far less so than those composed by the usual methods. When spread over white wood, without any preparation, it forms a solid glazing, and communicates a slight tint to the wood.

If it is required to charge this varnish with more copal, or prepared amber, the liquor must be composed of two parts of essence for one of oil.

To Apply Copal Varnish to the Reparation of Opake Enamels.

The properties manifested by these varnishes, and which render them proper for supplying the vitreous and transparent coating of enamel, by a covering equally brilliant, but more solid, and which adheres to vitreous compositions, and to metallic surfaces, admit of their being applied to other purposes besides those here enumerated.

By slight modifications they may be used also for the reparation of opake enamel which has been fractured. These kinds of enamel admit the use of cements colored throughout, or only superficially, by copal varnish charged with. coloring parts. On this account they must be attended with less difficulty in the reparation than transparent enamel, because they do not require the same reflection of the light. Compositions of paste, therefore, the different grounds of which may always harmonize with the coloring ground of the pieces to be repaired, and which may be still strengthened by the same tint introduced into the solid varnish, with which the articles are glazed, will answer the views of the artist in a wonderful manner.

The base of the cement ought to be pure clay without color, and exceedingly dry. If solidity be required, ceruse is the only substance that can be substituted in its place. Drying oil of pinks will form an excellent excipient, and the consistence of the cement ought to be such that it can be easily extended by a knife or spatula, possessed of a moderate degree of flexibility. This sort of paste soon dries. It has the advantage also of presenting to the colors, applied to it with a brush, a kind of ground which contributes to their solidity. The compound mastic being exceedingly drying, the application of it will be proper in cases where speedy reparation of the damaged articles is required.

In more urgent cases, the paste may be composed with ceruse, and the turpentine copal varnishes, which dry more speedily than oil of pinks; and the colors may then be glazed with the ethereal copal varnish.

The application of the paste will be necessary only in cases when the accident, which has happened to the enamel, leaves too great a vacuity to be filled up by several strata, of colored varnish.

But in all cases the varnish ought to be well dried, that it may acquire its full lustre by polishing. To make White Copal Varnish.

White oxide of lead, ceruse, Spanish white, white clay. Such of these substances as are preferred ought to be carefully dried. Ceruse and clay obstinately retain a great deal of humidity, which would oppose their adhesion to drying oil or varnish. The cement then crumbles under the fingers, and does not assume a body.