Gold leaf is a decorative material made from gold that has been beaten into extremely thin sheets. This ancient practice, known as goldbeating, has been used for millennia, dating back to ancient Egyptian times around 2600 BCE. The primary purpose of transforming gold into this fragile film is gilding—applying a thin layer of gold to a surface for aesthetic appeal. Gold leaf is valued for its intense color and resistance to tarnishing. It continues today for art, architecture, and culinary decoration.
Defining Purity: The Karat System
The amount of pure gold in gold leaf is determined by the karat system, a measure of fineness where 24 karats (24K) represents 99.9% pure gold. Gold leaf is available in a range of purities; 23-karat (95.8% gold) or 23.5-karat is often the standard for gilding applications.
Lower purity levels are created by alloying the gold with other metals, which changes the final color and physical properties of the leaf. Adding silver or palladium results in a paler “moon gold” or white gold leaf. Copper creates a redder gold leaf, while higher concentrations of silver yield “lemon gold” or “pale gold.” These added metals also increase the leaf’s strength, making it easier to handle during application.
A common purity is 22K (91.7% gold). While pure 24K gold never tarnishes, the non-gold metals in lower-karat alloys can oxidize over time when exposed to the elements. Therefore, high purity gold is preferred for outdoor architectural work to ensure longevity.
Physical Dimensions and Incredible Thinness
Gold possesses the highest malleability of any metal, allowing it to be beaten into a film that is nearly transparent. This extreme thinness is achieved through the meticulous process of goldbeating, where the gold is repeatedly hammered between layers of specialized material.
The resulting gold leaf typically measures between 0.1 and 0.125 micrometers (µm) in thickness. For perspective, a single sheet of copy paper is approximately 130 micrometers thick, and an average human hair is around 60 micrometers. Gold leaf is so thin that a slight breath or air current can easily cause it to wrinkle.
This extreme thinness means a small mass of gold can cover a surprisingly large area. One ounce of 24K gold can cover roughly 300 square feet. A single gram of pure gold can cover about 0.5 square meters. This makes gold leaf a cost-effective way to achieve a solid gold appearance over a vast surface area.
Real Versus Imitation Gold Leaf
It is important to distinguish real gold leaf from imitation leaf, which contains no actual gold. Imitation gold leaf is often called Dutch Metal, composition leaf, or brass leaf. This alternative is manufactured from an alloy of copper and zinc, blended to visually mimic the color and brilliance of real 23K gold.
Imitation leaf is significantly less expensive than genuine gold leaf, making it a popular choice for large-scale interior decorative projects. It is also much thicker than real gold leaf, which makes it easier for artisans to handle and apply. Other metal leaf alternatives include silver leaf (real silver) and imitation silver leaf (aluminum). A major drawback of imitation gold leaf is that it tarnishes and oxidizes over time, requiring a protective sealant, unlike pure gold leaf.
Safety for Consumption and Other Uses
One popular modern use for gold leaf is as an elegant garnish on food and beverages. The safety of consuming gold leaf is directly related to its purity. High-purity gold, 24K or food-grade gold between 22K and 24K, is considered biologically inert.
This inertness means the gold will not react with the body’s chemistry and will pass through the digestive system without being absorbed. Conversely, imitation gold leaf is not suitable for consumption because its copper and zinc components can be toxic if ingested. Only gold leaf explicitly labeled as edible, typically with a purity of 22K to 24K, should be used in food.
Outside of culinary uses, gold leaf is a staple material in non-consumable applications. It is utilized in the restoration of antique frames, furniture, and religious iconography. It is also applied to architectural elements, such as domes and statues, where its beauty and resistance to corrosion are prized.