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ANTIQUE FURNITURE RESTORATION DISCUSSION BOARD
Posted By: zhao biao <firstname.lastname@example.org> (188.8.131.52)
In Response To: Re: Gilt or gild? And how to restore. (Nancy)
Date: 2/5/4 07:07
In Response To: Re: Gilt or gild? And how to restore. (Nancy)
Dear Mr : My e-mail : email@example.com Gilding. Gilding is a term that applies not only to the fixing of gold leaf but also to the fixing of all other leaf or powdered metals to the surface of wood, paper, stucco, glass, metals, textiles, etc. It also covers bronzing and lacquering.
Materials. Gold Leaf. Gold is available in the form of leaf and powder. Gold leaf is made by rolling thin sheets of pure gold, alloyed with a small amount of silver, copper or other metal, in presses and placing the thin sheets between vellum sheets, and finally gold beaters' skin, and flattening them out with hammers. The hammering is carried out until the gold leaves are about 1/300,000 of an inch thick. These leaves are cut into squares(of around 10 square inches) and laid between the pages of small books, the pages of which are powdered to prevent sticking. Each book contains 25 leaves. The gold should assay at about 22 carats. Color variation is mainly controlled by the kind and amount of alloy used. Also the color of gold differs according to origin.The range of color is from red, orange, extra deep, medium, deep, pale,citron, green, lemon and white. Lemon and white are worth less than red and orange. Special gold leaf, for applying to exposed ironwork etc., is supplied in leaf about double the normal thickness. For very delicate work extra-fine leaf is supplied in very pure gold not less than 23 carats. This is the most expensive. Gold leaf for gilding glass is put in books without powdered pages and require careful handling and storage as they are easily ruined by dampness etc, causing all the leaf to stick together. Transferred gold is usually preferred as the gold leaf is pressed against white tissue paper which it adheres to until pressed against a more adhesive surface. Ribbon gold is gold leaf cut in thin strips and transfer-pressed on a roll of thin paper. This ribbon gold is made in various widths for line gilding and is usually applied by means of a gilding wheel. Powder gold is prepared from leaf gold; it is commonly supplied in the form of gold tablet or illuminating gold, the powder being mixed with weak gum water in moulds; or formerly as shell gold, the powder and gum water being dried in mussel or other shells. Gold substitutes. There are various alloys used to imitate gold; copper and tin; copper and aluminium; copper and zinc(Dutch metal) being one of the most common. All gold substitutes need to be protected by a coat of lacquer to keep their lustre and prevent tarnishing. Gold paint and liquid gold are bronze powders held in suspension in a suitable liquid medium.They need to be protected with a coat of lacquer or will soon tarnish on exposure to air. Trade secret. You can make a suitable lacquer by whisking the white of one large egg in about five ounces of water.
Mordants. Mordants is the name given to the various binding materials used as an adhesive coat for attaching the metal, either in leaf or powder form, to a surface. For exterior work, relief work, or work which is washed periodic-ally, either old oil gold size or japanners¡¯ gold size is employed. For interior work, such as frame or glass gilding, one of the various water sizes is commonly used.
Old Oil Gold Size.¡ªThis is prepared by allowing pure raw linseed oil to stand in an open jar for from six to twelve months, each month removing the skin which forms on the surface. When the oil has attained the right degree of tackiness¡ªwhich can only be determined by experiment¡ªit should be transferred to a closed vessel, adding a small quantity of litharge (1oz. to the lb.) and a little raw sienna, to provide suitable colouring; these should be well stirred in and the container securely corked. If, on using, it seems too thick for spreading to a thin, even coat, a little boiled linseed oil may be added.
Japanners¡¯ Gold Size.¡ªThis is a transparent, varnish-like liquid, ready for use, ranging in color from pale to dark. Its advantage lies in the comparative rapidity with which it dries, but against this must be set certain definite disadvantages. The gloss on the face of the gilding is not so deep as that which results from the use of old oil gold size, nor is the gilding so permanent. The present-day demand for speed, however, has considerably increased the use of japanners¡¯ gold size, and, generally speaking, the results which this gives are very satisfactory. The chief difficulty lies in gauging the right moment at which the leaf should be applied; the surface of the size, while retaining a certain degree of tackiness, should be un-affected by gentle pressure. As mentioned, gilders often darken oil gold size and japanners¡¯ gold size by adding a little raw sienna, Italian ochre or chrome, ground in oil. A dark luminous mordant is considered to act as a good foil for the gilding, ensuring greater depth and lustre. A slow-drying japanners¡¯ gold size is sold as ¡°writing gold size¡± for use in lettering, ticket-writing, etc. Water Sizes. Islnglass Size.¡ªThis is simply a weak solution of isinglass, made by pouring a pint of boiling water on to a teaspoonful of shredded isinglass in a clean vessel, covering it over and leaving it to dissolve for about twenty minutes. It is then stirred and strained through cotton wool. For best results it should be used while very warm. Mat Gold Size (for frames and smooth surfaces) is prepared by mixing eight ounces of gilders¡¯ clay, or fine clay, or Armenian bole with one ounce of mutton suet, straining through muslin and then adding sufficient hot parchment size, or hot leaf gelatine size, to make the substance into a thick cream. Four to six coats of this are applied before gilding, each coat being allowed to dry before another is applied. Burnish Size is prepared as above, but with the addition of one ounce of blacklead to the paste. This is used when the gold is to be finished with a high burnish, as it gives a stronger backing. Egg Size is prepared by beating up equal parts of yolk of eggs and glycerine with a little water. It is useful for applying gold leaf or powder to paper and other absorbent surfaces. Gum Water (a weak solution of gum Arabic in water) an inferior alternative used for this purpose. Jewelling cement and liquid glass are employed when applying ¡°speckles.¡± Spirit Varnish, applied and allowed to dry, is an excellent mordant for gold leaf when it is pressed down by a heated die, so as to form patterns. For this purpose blocking powders are also supplied. The powder is sprinkled over the surface to be decorated, the gold leaf laid on, and then the heated die pressed down.
Tools and Appliances. Various tools and appliances are needed to carry out gilding in its different branches. The standard equipment is listed below and should be adequate for the majority of circumstances.
Brushes should be of the first quality and must be kept in good condition by washing in turpentine when done with, greased with a little tallow or lard, and laid straight until again needed, when the grease is washed off in turpentine. For applying old oil size and japanners¡¯ size, red-sable hair brushes prove the most satisfactory for both decorators and sign writers, as they can be used flat for broad lines or brought to a fine flexible point. For running mouldings, beadings, and filling large letters, etc., cam el-hair swan-quill brushes or ¡°mops ¡° of fairly good size should be chosen. When laying size on broad surfaces, flat camel-hair varnish brushes will give good smooth surface and flat hog-hair varnish brushes suitable rough surface. For enriched mouldings, and all carved work, use round hog-hair pencils. For fine work, such as coach lining, ¡°coach liners¡± made of long brown sable hair, camel hair or fitch hair are supplied in many sizes, being mounted respectively in swan, goose, duck, crow, lark, and other quills. Size is generally applied with camel- hair mops, which are bushy and almost globular, if for fine work, or with flat camel-hair ¡°wash¡± brushes for broad surfaces and glass gilding. For running lines by the help of straight line, bevelled lining fitches are used. Round badger tools or camel-hair dabbers are often preferred for removing surplus gold from the edges of finished work, though usually this is done by means of dry or slightly damp cotton wool, which is also utilised for smoothing and pressing-down purposes.
Gilders¡¯ Tips.¡ªThese are thin, flat brushes made of badger or camel- hair, the hairs being held in place by two thin pieces of cardboard. They are used to pick up the gold leaf from the cushion and transfer it to the work and are made in various widths, ranging from three inches to half P4 an inch, to suit different kinds of work. At intervals the operator draws the tip over his hair or beard and from this action it acquires a certain amount of natural grease which enables the leaf to be conveyed.
Pounce Bags are made by taking small squares of coarse calico (from which all ¡°loading¡± must be washed out), spreading part of it with a thick layer of whiting or French chalk and then tying up tightly so as to form a bag. They are used for dusting ¡°tacky¡± surfaces before gilding,.. but should be used sparingly as whiting is liable to cause gold size to spread.
SkewingBags are made of three-cornered paper, rolled so as to form a conical receptacle about half a yard wide at the mouth, and are utilised to receive the ¡°skewings¡± or surplus gold or silver leaf as it is wiped off the work. These ¡°skewings¡± are sold to the leaf-metal beaters.
Fine-quality sponges and wash-leathers are also needed. These, like the cotton wool, must be quite free from hard spots or specks, as they are required for smoothing and wiping down. These materials after use, like the skewings, should be sent to the beaters, who recover the gold found on them.
Gilders¡¯ Knives have long, narrow, straight blades, like table knives. The cutting edge should not be too sharp, but must be free from notches or rust. The best quality have heavy handles, so that, being ¡°balanced,¡± the blades always stand clear of board or table and remain uppermost should they fall.
Burnishers are either dogs¡¯ teeth or agates mounted in handles. Agates are best, because they are cut in different sizes and shapes to suit various kinds of work. Sometimes burnishers are mounted on the opposite ends of camel-hair dabbers.
The Gilder¡¯s Cushion is an important item in the outfit. It is an oblong, rectangular board, commonly measuring 9 inches by 6 inches, and is covered with tough dressed calfskin, stretched over two or three layers of thick soft flannel. Beneath are suitable straps for receiving the thumb and fingers. At one end of the board is a screen of parchment or other suitable material serving as a guard to protect the gold leaves and prevent their being blown away. The leaves as wanted are laid on the pad and cut with a knife.
Lacquer is applied by a separate set of fine, soft hog-hair or badger hair brushes. These should be washed out with methylated spirit instead of turpentine. Lacquering must be done in a warm atmosphere.
Preparation of Surfaces Preparation before gilding must be adjusted to the nature of the surface. Painted surfaces must be quite dry and free from tackiness before applying mordant. Glossy paint and varnished surfaces show up gilding well, but they are troublesome if not perfectly dry. If there is the slightest suspicion of¡± tackiness¡± the surface must be pounced with the pouncing bag, or, if necessary, the surface can be covered over with weak glair.
Plaster or cement surfaces should be cleaned and then treated with jelly size laid on hot. Parian, Keene¡¯s, or similar glossy-surfaced cement should be treated with two coats of knotting, to be followed by one of old oil gold size or japanners¡¯ size.
Distempered walls or ceilings must be prepared by laying glair on the parts to be gilded as a priming for the oil or japanners¡¯ gold size.
Wood, unpainted, should be dressed with glair, either applied all over or on the parts to be gilded as a background for the old oil or japanners gold size. The surplus glair can be easily washed off.
Stone, including marble and granite, only requires to be cleaned before applying the size. Gilding on it is not very durable unless applied to incised lettering or ornamentation.
Iron must be clean. It should then receive one or two coats of knot-ting, which is allowed to dry before applying the size. Old painted ironwork should either have the old paint removed before applying the gold size or be dressed with two or more coats of quick-drying paint as a ground for the size.
Paper and cardboard should receive a coating of clear parchment or gelatine size and then the mordant.
Wall hangings of the Anaglypta type may have gold size applied to painted surfaces.
Textiles, such as silk, linen, etc., must have the parts to be gilded coated with glair before applying the old oil gold size. Glass requires no other preparation for the mordant than thorough cleaning. This applies also to French polished work, which provides a good ground for gilding.
Leather must be cleaned, damped, and dressed with parchment size if to be gilded all over, or with French spirit leather varnish (spirit varnish containing a small amount of linseed oil) for part and embossed gilding.
Wire blinds and similar articles must have the parts to be gilded first filled up by painting with ¡°coach filling,¡± or with a paint compounded of paste white lead mixed with equal parts of japanners¡¯ gold size and turpentine, worked into a thick cream. This will take the old oil or japanners¡¯ gold size.
Setting Out the Design Where gilding is only partial, that is to say when lines or patterns are to be covered with gold, silver, etc., the design can either be traced out with pipeclay, soft chalk, or crayon on the surface, or the design can be drawn on ¡°lining¡± paper and then traced on to the surface. Lettering and straight lines are often traced by means of a chalked line (a soft cotton string rubbed with chalk which is held taut in the right position and then plucked up and allowed to ¡°strike¡± out a faint white line on the surface). In some cases a ¡°pricked¡± design is laid on the surface and traced by pouncing in oil gilding it is wise to pounce the surface lightly or to apply glair before the sizing. Some gilders when dealing with varnished work prefer to gild on the mat surface and then varnish round the gilding. But this gives dull results and makes varnishing difficult. Old oil gold size should flow easily, produce a thin film, drying without wrinkles and with a high gloss. If too thick it may be thinned by the addition of a little boiled oil. It should remain slightly tacky for from three to seven days. It is applied with a sable or camel-hair brush as described above, and selected as to shape and size for the special work in hand. The size should be applied thinly and smoothly, and all ragged or ¡°fat¡± edges wiped off. The gold leaf is then laid on. In doing this it is necessary to see that each leaf z should overlap the next by about the eighth of an inch and should thoroughly cover the pattern. The leaf is then carefully pressed down with a cotton-wool pad, wash-leather, or camel-hair dabber to secure a smooth surface and close adhesion. This done, the dabbing is carried on with a slight circular rubbing movement, to remove the surplus gold, which is caught in the skewing-bag. japanners¡¯ gilding is carried out as above, but in this case gilding must follow on quickly after the application of the size, as it dries rapidly. For the same reason the cotton-wool pad or dabber should be used promptly after laying on the leaf, first pressing firmly and then rubbing gently. E-mail : firstname.lastname@example.org
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