Part 448

TRAGACANTH, MUCILAGE OF: See Adhesives, under Mucilages.

«TRANSPARENCIES:»

See also Photography.

A good method of preparing handsome London transparencies is as follows:

White paper is coated with a liquid whose chief constituent is Iceland moss strongly boiled down in water to which a slight quantity of previously dissolved gelatin is added. In applying the mass, which should always be kept in a hot condition, the paper should be covered uniformly throughout. After it has been dried well it is smoothed on the coated side and used for a proof. The transparent colors to be used must be ground in stronger varnish than the opaque ones. In order to produce a handsome red, yellow lake and red sienna are used; the tone of the latter is considerably warmer than that of the yellow lake. Where the cost is no consideration, aurosolin may also be employed. For pale red, madder lakes should be employed, but for darker shades, crimson lakes and scarlet cochineal lakes. The vivid geranium lake gives a magnificent shade, which, however, is not at all fast in sunlight. The most translucent blue will always be Berlin blue. For purple, madder purple is the most reliable color, but possesses little gloss. Luminous effects can be obtained with the assistance of aniline colors, but these are only of little permanence in transparencies. Light, transparent green is hardly available. Recourse has to be taken to mixing Berlin blue with yellow lake, or red sienna. Green chromic oxide may be used if its sober, cool tone has no disturbing influence. Almost all brown coloring bodies give transparent colors, but the most useful are madder lakes and burnt umber. Gray is produced by mixing purple tone colors with suitable brown, but a gray color hardly ever {710} occurs in transparent prints. Liquid siccative must always be added to the colors, otherwise the drying will occupy too much time. After the drying, the prints are varnished on both sides. For this purpose, a well-covering, quickly drying, colorless, not too thick varnish must be used, which is elastic enough not to crack nor to break in bending.

Frequently the varnishing of the placards is done with gelatin. This imparts to the picture an especially handsome, luminous luster. After an equal quantity of alcohol has been added to a readily flowing solution of gelatin, kept for use in a zinc vessel, the gelatin solution is poured on the glass plates destined for the transparencies. After a quarter of an hour, take the placard, moisten its back uniformly, and lay it upon a gelatin film which has meanwhile formed on the glass plate, where it remains 2 to 3 days. When it is to be removed from the plate, the edge of the gelatin film protruding over the edge of the placard is lifted up with a dull knife, and it is thus drawn off. A fine, transparent gloss remains on the placard proper. In order to render the covering waterproof and pliable, it is given a coating of collodion, which does not detract from the transparence. The glass plates and their frames must be cleaned of adhering gelatin particles before renewed use.

«TRANSFER PROCESSES:»

«To Transfer Designs.»—Designs can be transferred on painted surfaces, cloth, leather, velvet, oil cloth, and linen sharply and in all the details with little trouble. Take the original design, lay it on a layer of paper, and trace the lines of design accurately with a packing needle, the eye of which is held by a piece of wood for a handle. It is necessary to press down well. The design becomes visible on the back by an elevation. When everything has been accurately pressed through, take, e. g., for dark objects, whiting (formed in pieces), lay the design face downward on the knee and pass mildly with the whiting over the elevations; on every elevation a chalk line will appear. Then dust off the superfluous whiting with the fingers, lay the whiting side on the cloth to hold it so that it cannot slide, and pass over it with a soft brush. For light articles take powdered lead pencil, which is rubbed on with the finger, or limewood charcoal. For tracing use oil paint on cloth and India ink on linen.

«To Copy Engravings.»—To make a facsimile of an engraving expose it in a warm, closed box to the vapor of iodine, then place it, inkside downward, on a smooth, dry sheet of clean white paper, which has been brushed with starch water. After the two prepared surfaces have been in contact for a short time a facsimile of the engraving will be reproduced more or less accurately, according to the skill of the operator.

«To Transfer Engravings.»—The best way to transfer engraving from one piece to another is to rub transfer wax into the engraved letters. This wax is made of beeswax, 3 parts; tallow, 3 parts; Canada balsam, 1 part; olive oil, 1 part. If the wax becomes too hard, add a few drops of olive oil, and if too soft, a little more beeswax. Care should be taken that the wax does not remain on the surface about the engraving, otherwise the impression would be blurred. Then moisten a piece of paper by drawing it over the tongue and lay it on the engraving. Upon this is laid another piece of dry paper, and securing both with the thumb and forefinger of the left hand, so they will not be moved, go over the entire surface with a burnisher made of steel or bone, with a pointed end. This will press the lower paper into the engraving and cause the wax to adhere to it. Then the top paper is removed and the corner of the lower one gently raised. The whole is then carefully peeled off, and underneath will be found a reversed, sharp impression of the engraving. The edges of the paper are then cut so it can be fitted in a position on the other articles similar to that on the original one. When this is done lay the paper in the proper position and rub the index finger lightly over it, which will transfer a clear likeness of the original engraving. If due care is taken two dozen or more transfers can be made from a single impression.

TRICKS WITH FIRE: See Pyrotechnics.

TUBERS, THEIR PRESERVATION: See Roots.

TUBS: TO RENDER SHRUNKEN TUBS WATER-TIGHT: See Casks.

TUNGSTEN STEEL: See Steel.

TURMERIC IN FOOD: See Foods.

TURPENTINE STAINS: See Wood. {711}

TURTLE (MOCK) EXTRACT: See Condiments.

«TWINE:»

See also Thread and Cordage.

Tough twine may be greatly strengthened by dissolving plenty of alum in water and laying the twine in this solution. After drying, the twine will have much increased tensile strength.

«Typewriter Ribbons»

(See also Inks.)

The constituents of an ink for typewriter ribbons may be broadly divided into four elements: 1, the pigment; 2, the vehicle; 3, the corrigent; 4, the solvent. The elements will differ with the kind of ink desired, whether permanent or copying.

«Permanent (Record) Ink.»—Any finely divided, non-fading color may be used as the pigment; vaseline is the best vehicle and wax the best corrigent. In order to make the ribbon last a long time with one inking, as much pigment as feasible should be used. To make black record ink: Take some vaseline, melt it on a slow fire or water bath, and incorporate by constant stirring as much lampblack as it will take up without becoming granular. Take from the fire and allow it to cool. The ink is now practically finished, except, if not entirely suitable on trial, it may be improved by adding the corrigent wax in small quantity. The ribbon should be charged with a very thin, evenly divided amount of ink. Hence the necessity of a solvent—in this instance a mixture of equal parts of petroleum benzine and rectified spirit of turpentine. In this mixture dissolve a sufficient amount of the solid ink by vigorous agitation to make a thin paint. Try the ink on one extremity of the ribbon; if too soft, add a little wax to make it harder; if too pale, add more coloring matter; if too hard, add more vaseline. If carefully applied to the ribbon, and the excess brushed off, the result will be satisfactory.

On the same principle, other colors may be made into ink; but for delicate colors, albolene and bleached wax should be the vehicle and corrigent, respectively.

The various printing inks may be used if properly corrected. They require the addition of vaseline to make them non-drying on the ribbon, and of some wax if found too soft. Where printing inks are available, they will be found to give excellent results if thus modified, as the pigment is well milled and finely divided. Even black cosmetic may be made to answer, by the addition of some lampblack to the solution in the mixture of benzine and turpentine.

After thus having explained the principles underlying the manufacture of permanent inks, we can pass more rapidly over the subject of copying inks, which is governed by the same general rules.

For copying inks, aniline colors form the pigment; a mixture of about 3 parts of water and 1 part of glycerine, the vehicle; transparent soap (about 1⁠/⁠4 part), the corrigent; stronger alcohol (about 6 parts), the solvent. The desired aniline color will easily dissolve in the hot vehicle, soap will give the ink the necessary body and counteract the hygroscopic tendency of the glycerine, and in the stronger alcohol the ink will readily dissolve, so that it can be applied in a finely divided state to the ribbon, where the evaporation of the alcohol will leave it in a thin film. There is little more to add. After the ink is made and tried—if too soft, add a little more soap; if too hard, a little more glycerine; if too pale, a little more pigment. Printer’s copying ink can be utilized here likewise.