There are several types of metal leaf that are used for gilding, gold is simply the most well known. It can be purchased as pure genuine gold leaf, which is the most expensive and it is often tied to the market price of gold. There is also an imitation or composition gold leaf that is a copper/zinc blend that looks exactly like gold but is still a real metal leaf. Additionally, there is pure silver leaf, copper leaf and variegated composition leaf which has a mix of metals in a fantastic array of patterns and colors, including as red, green and blue. I used a variegated silver/copper leaf in a framed fretwork project to simulate fire on the letters of the word "fire". So there are a lot of metal finishes to choose from than simply gold.
Gold leaf traditionally comes in books of 25 leaves, with each leaf being approximately 3" square and separated by sheets of tissue. The variegated variety comes in 5" sheets and is also separated by tissue sheets, as do some brands of composition leaf. It is less than a micrometer thick (typically about 100 nm). Being extremely thin, it cannot be touched or handled and must be applied directly from the book. It is so delicate that a puff of air can crumpled the leaf, so either hold your breath periodically while placing a piece of leaf on your project, or wear a pollen mask to divert the air flow.
Genuine gold leaf with a karat rating of 22kt or higher does not require sealing. However, a protective coat of sealer is strongly suggested to insure the durability of the leaf, particularly in high traffic areas or for heavy-use objects and furniture. Imitation gold, silver and copper leaf must be sealed or they will tarnish. Sealer is available in gloss and satin finishes and may be applied by brush or spray, depending on the brand.
Other than the care which must be used in handling the fragile metal leaf, theres really nothing difficult about it. You need only a minimum of tools, a 1" varnish brush for applying the "size"; a soft 2" brush for pouncing the leaf to adhere it; and a cotton ball for burnishing it when finished.
The surface to be gilded must be perfectly smooth and non-porous. If necessary, lightly sand the surface with 220 grit sandpaper to remove any blemishes, since any irregularities, even brush marks, will show through the thin gold leaf. Remove the sanding dust with a tack cloth.
If the surface is porous, it must be given several coats of flat paint or shellac, or you can use a primer-sealer that has been specially formulated for gilding. This base color is also referred to as the 'Bole' color. Traditionally, bole was made from clay, but today paint is typically substituted women's jackets . Ochre, gray or red boles are traditionally used as fault hiding bases or as color enhancing undertones. Your choice of bole or paint color will affect the overall appearance of the finished product, but traditionally, red-brown bole is used as a base for gold and black bole for silver.
Before applying transfer gilding, make sure that the surface has been coated with "size" which is usually a thin brownish red adhesive when using gold as the leaf. Size refers to the adhesive used to adhere the leaf to a surface. Apply carefully and evenly, working the size to an even film as much as possible and avoiding visible brush strokes and making sure no spots are missed. Do not cover the whole item at once, but work in sections if the object is large.
You can use low-tack painters tape to keep the size off of any areas that you do not want to gild.
The most important phase in achieving a professional looking gilt surface is determining the right degree of tackiness of the size to ensure that the gold adheres properly to the surface. As your 'size' dries it naturally goes from a wet to a dry state. The proper time to apply your leaf is when the 'size' is not wet but 'tacky', just before it dries completely. Different brands have different tack times, so follow the manufacturers' instructions.
While it is drying, the object should be protected from dust and lint. The drying test can made by touching the size in an out of the way place with your knuckle. When it sticks to the surface very slightly, the sized surface is ready to be gilded.
Placing a book of leaf in your hand, carefully fold back the tissue paper to expose the gold leaf. Position the sheet above where you want to put it and lightly lay the leaf onto the sized area and then carefully 'roll' out the leaf. The leaf will pull away from the tissue as soon as it touches the tacky varnished surface Hold firmly and carefully and slowly let the leaf attach to the surface.
After the leaf is laid on, cover the placed leaf with a piece of tissue paper, and press it down lightly with your finger, and then pounce the leaf into the size with a soft brush, to ensure complete adhesion. Use the brush to crowd the leaf into any crevices or hollows or grooves in the surface, but do it lightly. Repeat this procedure until the required area is covered, but remember that each piece of gold leaf is lapped just slightly with the previous piece has you go along.
Touch up any areas that are missing leaf due to lack of sufficient sizing or from leafed areas that may have torn away during burnishing. Any skips can be patched with scraps of gold picked up with a damp toothpick. Avoid crumbling the leaf.
After you project is completed, the leaf is finally burnished with a cotton ball by rubbing it briskly without pressure. If the gilded surface will be subjected to wear, it should sealed with a clear protective coating as mentioned above.
Gilding with gold leaf can be easy if you work carefully, and the results are strikingly beautiful.
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