GOLD LEAF

Mechanical Surface Gilding for Jewellers
©SANDRA NOBLE GOSS

[These advanced techniques assume that you have basic jewellery and metalworking skills. We offer these technical papers, originally presented as workshops, in a spirit of sharing information. We assume no liability for safety and health issues -- those are your responsibility. Please read Artist Beware by Michael McCann or The Artist's Complete Health & Safety Guide by Monona Rossol.]

Gold leaf is the thinnest sheet of gold available to jewellers. The more malleable and ductile a metal, the better its ability to be beaten into leaf. Thus, gold is an ideal metal for making leaf. Leaf metal varies from 1/8000 mm to 1/10,000 mm in thickness.

-Gold and silver leaf can be applied to metal jewellery (cast or fabricated), wood, plastic, stone or plaster.
-The application of gold leaf to a surface is a mechanical cold gilding process not a chemical bonding (as in electroplating).
-Gold leaf should be applied to surfaces which are free from abrasion (in recessed areas) or protected with a lacquer.

Metal leaf is available in a variety of forms:
• 22k or 23k Deep Gold Leaf
• 22k or 23k Transfer Gold Leaf (sticky back)
• Silver Leaf (fine silver)
• Imitation Gold Leaf (a.k.a. "Dutch Metal", "Brass leaf", "Composition Leaf")
• Aluminum Leaf ("Imitation Silver leaf")
• Variegated Leaf (different colours - red, blue, green)
• Copper Leaf

Gold leaf will not tarnish. The silver, imitation gold, copper all will tarnish, so should be covered with a protective coating. (varnish, spray fixative, urethane etc.)

Leaf is sold by the "book" - each book contains 25 "leaves" 3 3/8" x 3 3/8" (85mm x 85mm). Suppliers: try art supply stores, sign painter's supplies, metal refiners. In Toronto, Curry's Art Supplies sells 22k gold leaf from West Germany made by Georg Renner GMBH and Graphic Commerce Ltd. sells 23k Florence gold leaf from Italy. Each leaf of gold is separated from the other leaves with thin paper, producing the "book".

MECHANICAL SURFACE GILDING: PROCESS

GOLD SIZE: Gold Leaf is attached to the metal or base material with an adhesive known as gold size. (It is more of a varnish, than a glue.) Gold size, or gilder's varnish, comes in two forms - quick-drying or slow-drying. Quick-drying drys in about 30 minutes to 1 hour; slow-dry may take 12 - 16 hours (good for large intricate projects; most jewellery uses need only the quick drying size). There are also water-based gold sizes.

Application: The surface to which the leaf is to be applied should be clean of grease. It should also be scratch brushed or sanded with emery paper to provide a slightly matte surface for the size. Brass or copper can be patinated black with cupric nitrate to provide a good gilding surface. Wood or other porous surfaces should be sealed first, with paint or primer.

Gold size is painted onto the surface to be gilded with a brush (clean brush with mineral spirits afterward), and allowed to dry until it is tacky to the touch. One usually tests for correct tackiness by touching the surface with the knuckle (less likely to be greasy). "It should not stick, but when pulled away, you should feel a slight pull and hear a slight 'tick'." (Jewelry Concepts and Technology, Oppi Untracht pg. 665). If the size is too wet, it will work its way up through the gold leaf and leave a sticky surface. If it is too dry the leaf will not adhere.

When the size is the correct tackiness, you may apply the leaf.

When applying the gold leaf, work in a draft-free environment. You can apply the entire sheet at one time on larger surfaces using a "gilder's tip" (a soft brush the same width as the leaf), or you can tear off smaller pieces of leaf and apply them with a small brush. A natural bristle brush (sable) can be used. The leaf is picked up with the brush by charging the brush with static electricity (traditionally by rubbing the brush on one's hair). The leaf will attach to the electrically charged brush, but will easily disengage from the brush when touched to the size surface.

When the surface is covered, burnish the gold leaf onto the size gently with the brush or a cotton swab. It can then be burnished further with a fingertip. A second layer of gold leaf may be applied over the first, by applying more size and following the same procedure. This is useful in applications where a thicker layer of gold is required.

Gold leaf will not tarnish and therefore doesn't need any other surface treatment. (The imitation leaf does.) If you want to give it a protective coating, you can spray with a clear acrylic spray or clear lacquer (Krylon, Tremclad, urethane - matte finish or gloss). Make certain size is totally dry before applying protective coating.

Textures, Scraffitto & Patina:

Texture: Because gold leaf is so thin, it will show any texture imprinted on the base metal. The metal is first textured, then the gold size and leaf are applied as above.

Scraffitto: Fine lines can be scratched through the gold leaf surface with a scriber.

Rocketfish Pin: Brass, Patina, Gold Leaf. 8 cm. ©Andrew Goss

Patina: Cupric nitrate patina can be applied to the gold leaf when the leaf is applied on metal, giving an "antiqued" effect. Let size dry really well (overnight). Paint on cupric nitrate solution and heat carefully with a small, gentle flame until the patina just turns black. [Toxic fumes: this should only be done under a proper fume hood. Wear gloves.] If the gold size bubbles under the leaf you are heating too fast or the size was not dry enough. Wash off excess patina and coat with spray lacquer. This patina needs to be protected with sealer. For patina recipes and techniques we recommend The Colouring, Bronzing, and Patination of Metals: A Manual for the Fine Metalworker and Sculptor by Richard Hughes.

©Sandra Noble Goss

Back to techniques page

Sandra Noble Goss
sng"AT"sandragoss.com
(Please copy and paste the address into your email program
- then replace "AT" with the @ symbol)
781 Second Avenue West, Owen Sound, Ont., N4K 4M2 Canada
Tel: (519)371-1857