Glossary of Metal Materials
The following glossary terms are broken down into sections: metals, quality, and form. Metals section defines different types of precious and non-precious metals that are most often associated with illumination. Quality defines the different levels of metal grade used in gilding, and the Form section defines the different styles you can buy these metals.
Precious & Non-precious Metals
* Denotes a material available prior to the 16th century.
A metallic yellow or yellow-brown precious metal. It can be found naturally in its pure form. Gold can be found around the world in areas where there are strong quartz veins naturally occurring in rock formations. In medieval times, gold was mined and imported from West Africa. Today the largest miner of gold is South Africa.
A metallic white-grayish precious metal. It can be found naturally, but this is very rare. Most silver is extracted from mineral deposits and from other alloys. Most silver is found in areas of active volcanic and hydrothermal areas. In the medieval times, most silver was mined in Northern and Eastern Europe. Today most silver comes from Nevada, in the USA.
A metallic silverish-white precious metal. It can be found naturally in the Earth’s surface layers. Platinum was essentially unknown in the medieval times. It was first referenced in European writings in the 16th century but it wasn’t until 1748 that it began to be investigated by scientists. Today Platinum is mostly found in South Africa.
A metallic silver precious metal. It can be found naturally in ore deposits throughout the world but most often it is found alloyed with other metals. In the medieval times palladium was unknown and it was first discovered in 1803. It is the most rare of the precious metals. Today Russia is the largest producer of palladium.
A metallic silver-white metal. It can be found naturally in the Earth’s crust and core. Nickel can also be found in meteorites. Nickel was unknown in medieval times and was first discovered in Sweden 1757. Today, Canada produces most of the world’s nickel.
A metallic reddish-brown metal. It can be found naturally, but is most often found in mineral deposits. Copper is most often found in areas where there are high concentrations of minerals such as volcanic seas. In medieval times most of Europe’s copper came from Sweden. Today most copper is mined in Chile and Utah in the USA.
A metallic silverish-white to a dull gray metal. It does not occur naturally and is most often found in mineral deposits. It must be chemically extracted and refined. It is the most common metal found within the Earth’s crust. In the medieval times, alum salt and clays were often used, but Aluminium in its pure metal form was not known until the 1800’s. Today China produces the most Aluminium.
A metallic silver-yellow precious metal. White gold is not a naturally occurring metal. It is an alloy (a combination of other metals) made of gold and at least one white metal such as nickel, silver, or palladium. White gold was not known during medieval times and was not commercially available until 1912.
A metallic silver-red precious metal. Rose gold or red gold is not a naturally occurring metal. It is an alloy (a combination of other metals) made of gold and and copper. Rose gold was not known during medieval times and was first created in Russia in the 19th century.
A metallic silver-yellow precious metal. Yellow gold is not a naturally occurring metal. It is an alloy (a combination of other metals) made of gold, copper, and silver. Yellow gold was not known during medieval times and wasn’t commercially available until the early 1900s.
A metallic silver-yellow precious metal. Moon gold is not a naturally occurring metal. It is an alloy (a combination of other metals) made of gold and palladium. Moon gold was not known during medieval times and wasn't commercially available until the early 1900s.
A metallic white-gray precious metal. Sterling silver is not a naturally occurring metal. It is an alloy (a combination of other metals) made of silver and copper. Sterling silver was not known until the very end of the medieval times. Sterling silver was first produced in the 12th century.
A metallic gray metal. Pewter is not a naturally occurring metal. It is an alloy (a combination of other metals) made of tin, lead, and copper. In modern times the lead has been replaced with antimony. Pewter was first used in 1450 BC and most of the medieval supply came from Britain. Today Malaysia is the largest producer of pewter.
A multicolor rainbow metal. Variegated metal is not a type of metal, but a process to metal which creates abstract random color differentiations. The process of variegated metal can include heat, acids, and other like treatments which alter the base material. The most common type of variegated metal is one with a copper base.
All genuine leaves are 99.9% pure metal or are an alloy (a combination of metals) that contains a percentage of gold. All genuine leaves that use gold in their formula are measured by karat [k] (the level of purity or fineness). Most genuine metal leaves range from 12-24k. Genuine leaves like silver, palladium, or copper do not use the karat ranking system and are listed as 99.9% pure and genuine. Genuine leaves are extremely delicate and thin and must be handled with a tool or brush when using.
Also known as Dutch metal, composition metal and schlagmetal, imitation leafs are alloys (a combination of other metals). Unlike genuine leaves, imitation leaves do not contain any gold. The most common imitation leaf is “imitation gold” which is a misnomer, as imitation gold is 85% copper and 15% zinc and contains no gold whatsoever. Because it is made from more common metals, it is much cheaper than genuine leaf and can be found widely. Imitation leaf is also much thicker then genuine leaf and can usually be handled with clean dry hands.
Karat or Carat
Karat [k or kt] or Carat [c or ct] is a measurement of the fineness (purity) of gold. A single karat is 1/24 part or 4.1667 percent. Gold in its purest form is 24/24 karats, called 24k gold. Anything less than 24k gold notes that the gold has impurities or contains other metals (alloys) thus, an object that contains 16/24 parts gold and 8 parts alloying metal is 16-karat gold. Gold or any gold alloy more than 22k will not tarnish over time. Any gold alloy below 22k must be sealed to prevent tarnishing. Below is a list of the most common gold alloys and their fineness. This is a general guide as manufacturers can use slightly different formulas to create their gold leaf.
24k Gold - 99.9% Gold
23k Gold Alloy - 95.8% Gold + 4.2% Silver & Copper
22k Gold Alloy - 91.8% Gold + 8.2% Silver & Copper
22k Yellow Gold - 91.7% Gold + 8.3% Copper & Silver
22k Moon Gold - 91% Gold + 9% Palladium
18k Gold Alloy - 75% Gold + 25% Silver
18k Yellow Gold - 75% Gold + 12.5% Copper + 12.5% Silver
18k Dark Yellow Gold - 75% Gold + 15% Copper + 10% Silver
18k White Gold - 75% Gold + 25% Nickel or Silver or Palladium
18k Red Gold - 75% Gold + 25% Copper
18k Rose Gold - 75% Gold + 22.25% Copper + 2.75% Silver
18k Pink Gold - 75% Gold + 20% Copper + 5% Silver
12k Gold Alloy - 50% Gold + 50% Silver
12k Red Gold - 50% Gold + 50% Copper
Alloys are metals that are mixed and added to other metals to increase the hardness and durability, alter colors, decrease the cost per weight, or avoid the cost of high-purity refinement. The cost of alloyed metals are much cheaper than those in their purest form.
Gold leaf, sometimes called gold foil, is gold that has been beaten into a very thin sheet that averages about 0.12 microns in thickness. For comparison, copier paper is around 130 microns, and human hair around 60 microns. Gold leaf is so thin that when holding it up to a bright light, the light can be seen through it. Blowing on a gold leaf will disturb it, and touching it with a finger will destroy it. Because of its thinness, a sheet of gold leaf rubbed between your hands will virtually disappear, leaving only a slight sheen.
Loose Leaf/Surface Leaf
Loose leaf is thin sheets of metal leaf that are placed between two pages of thin rouged tissue paper inside a small booklet. When flipping through the booklet the leaves can easily be disturbed and wrinkle or fly out of the book by the slightest current of air. The gilder can slowly remove one leaf at a time without disturbing the remaining leaves by working slowly and using a gilders tip or other tool.
Patent Leaf/Transfer Leaf
Patent leaf is thin sheets of metal leaf that are mounted on it’s own sheet of tissue paper using a pressure process and then placed between two pages of thin rouged tissue paper inside a small booklet. When flipping through the booklet the leaves will not be disturbed or wrinkle. The gilder can slowly remove one sheet at a time and cab use a gilder’s tip or scissors to cut the leaf to size.
Most gold and gold alloy leafs are sold as single leaf. Double and triple leaf gold means that more gold is added to each sheet making the leaf denser and firmer and less likely to show wrinkles. This does increase the thickness of each sheet by a very small amount. Usually between 2 and 4%.
The small pieces of leftover metal leaf. Most often these skewings are collected and ground down and used with a binder to create a paint.
Powder metal is made from the small flakes of metal leaf called skewings ground down to a fine power. Artists often mix this powder with a binder to create a metal paint which can be buffed to a fine shine.
Shell metal is made from the small flakes of metal leaf called skewings ground down to a fine powder and mixed with a binder to create a metal paint that can be buffed to a fine shine. Shell metal can be reconstituted with water indefinitely.
Flake metals are no different to skewings. Flakes can be purchased as is and do not have to be collected from leftover metal leafs.