How to Apply Gold Leaf to Exterior Surfaces

Composition, karat level, and weight. This detailed guide will assist you in selecting the optimal gold leaf for outdoor applications, ensuring durability and visual excellence.

Choosing the Correct Gold Content

Gold leaf is available in a variety of karat levels and colors, influenced by its metal composition. Pure gold, known as 24kt gold, can be mixed with other metals like copper and silver to achieve different hues and durability characteristics:

• Copper: Adding copper results in a warmer, richer tone.
• Silver: Mixing in silver gives the leaf a paler, cooler tone.

These additions affect the karat value of the gold leaf, which typically ranges from 6kt (indicating lower purity and more added metals) to the purest form at 24kt "Fine Gold".

Corrosion Resistance and Longevity

While 24kt (Pure) gold is inherently resistant to corrosion, the addition of silver and copper can decrease its durability. However, the levels of these metals in high-karat leaves (such as 23.75kt or 23kt) are minimal, allowing the leaf to maintain its integrity and appearance outdoors for over 30 years. For permanent outdoor installations like domes, architectural details, or statues, a gold leaf with a purity of 96% to 98.5% is ideal.

Leaf Thickness and Weight Considerations

The thickness of gold leaf is crucial for its endurance against environmental elements. It is typically measured in grams per 1,000 leaves:

• A heavier leaf, ranging from 18 to 23 grams per 1,000 leaves, is recommended for exterior uses to withstand the abrasive effects of weather conditions such as snow, rain, and wind.

This guide provides you with a comprehensive understanding to make informed choices about gold leaf for your exterior gilding projects, ensuring both aesthetic appeal and long-lasting results.

Application Technique

Priming the surface

To ensure that the gold leaf adheres well and displays its full splendor, it's crucial to prepare your surfaces—be it metal, stone, wood, or plastic—with a high-quality primer. For outdoor metal gilding projects, we advocate using a 'Burnish Sealer'. This specialized primer-sealer, available in Red, Gray, and Ochre, is engineered to provide an optimal foundation for the gilding adhesive. The color choices, particularly Red or Ochre, are ideal for underlaying genuine gold leaf, enhancing the depth and richness of the gold's appearance.

When working with stainless steel, a specific 'etching primer' is necessary instead of the typical solvent-based, alkyd primers, to achieve proper adhesion. This ensures that the gold leaf application remains intact and vibrant. If you're uncertain about the right products or techniques for your gilding project, feel free to reach out for guidance.

Applying the Adhesive Sizing

Adhesive sizing, commonly referred to simply as "size," is essential for attaching gold, silver, or metal leaf to surfaces. The choice of size can vary, depending on the desired finish. For applications involving genuine gold, silver, or metal leaf on metal surfaces, we recommend using LeFranc Mixtion, available in both 3-hour and 12-hour drying times. This traditional, clear, natural oil-based adhesive is crafted in France and is renowned among professional gilders for its superior quality and reliability in crucial projects.

In addition to LeFranc, we also offer Dux oil sizing, a high-quality option manufactured in the USA. Dux is available in Quick Dry and Slow Set options to accommodate different working times and project needs.

When applying size, it is crucial to ensure even coverage without excess. Special attention should be paid to ornamental and recessed areas to prevent pooling. For a comprehensive guide on how to apply size, including tips on achieving the correct film thickness and understanding drying and tack times, check out our video tutorial on 'Gilding on Metal Surfaces'. This resource offers valuable insights into professional gilding techniques and best practices.

Mastering the 'Tack' Test

The 'tack' test is a critical step in ensuring a professional-quality gilding finish. It involves precisely timing the application of the gold or metal leaf during the drying phase of the adhesive sizing. The ideal moment for application is when the size transitions from its wet state to a 'tacky' state—moist enough to bond yet not fully dry. This delicate balance is key to avoiding either premature or insufficient adhesion.

Understanding and executing the tack test effectively can greatly influence the final appearance and durability of the gilding project. The size should feel sticky to the touch but should not leave any residue on your fingers. Applying the leaf too early or too late can compromise the adhesion and overall quality of the finish.

For an in-depth guide on how to perform the tack test correctly and ensure optimal timing for your gilding projects, refer to our detailed video tutorial titled 'Gilding on Metal Surfaces.' This tutorial provides step-by-step instructions and expert tips to help you achieve flawless results when working with genuine or metal leaf.

Opt for 23kt or Higher Genuine Gold Leaf for Exterior Gilding

For superior exterior gilding, we recommend using genuine gold leaf with a minimum of 23 karats. The 23.5 karat gold leaf, ideal for outdoor applications, ensures both durability and longevity, preventing degradation and maintaining its luster over time. Less pure forms of gold leaf may not withstand the elements as effectively, leading to quicker deterioration and loss of aesthetic appeal.

Available Forms of Gold Leaf

• Individual Sheets: Each sheet measures 3 3/8" x 3 3/8", perfect for detailed application.
• Patent Leaf: Each leaf is adhered to a piece of wax paper, facilitating easier handling and application. This format is particularly beneficial for large-scale exterior projects, allowing for more efficient and precise application.
• Rolls: Offering continuous rolls of genuine gold leaf, measuring 4 1/8" wide and extending up to 68 feet, ideal for covering large surfaces seamlessly.

Using patent gold leaf significantly enhances the application process outdoors, as the wax paper backing supports easier manipulation and positioning of the gold leaf, ensuring a smooth and even coverage.

Explore Our Extensive Gold Leaf Collection

Explore our extensive collection of the finest genuine gold leaf, sourced from the renowned regions of Italy, Germany, France, and China. Our selection ranges from the purest 24 karat gold to 6 karat options, catering to a variety of artistic and architectural needs. Whether you're restoring historical monuments or creating new, eye-catching exterior features, our high-quality gold leaf options are designed to meet the highest standards of gilding craftsmanship.

Burnishing and Cleaning Off Gold Leaf

To achieve a flawless finish when gilding, we recommend using a soft-haired Squirrel mop brush for the removal of excess gold leaf and for polishing the gilded surface. Ensure complete coverage of gold on the project surface before initiating the cleaning process with your mop brush. Fill any voids or gaps to prevent uneven textures and appearances.

After applying the gold leaf, gently brush away excess flakes with the mop brush, leaving a slight residue of gold dust. This step is crucial—avoid vigorous brushing immediately after application as the adhesive beneath the gold leaf is still tender and the gold may appear dulled if disturbed excessively. Allow the surface to settle overnight, letting the adhesive cure fully.

Return the following day to complete the final burnishing phase. Use a piece of soft cotton to lightly buff the surface, removing any lingering pieces of gold leaf. This gentle approach helps achieve a beautifully polished, uniformly gilded surface that enhances the ornamental value of your project.

Sealing and Finishing Off Gold Leaf Applications

Genuine gold leaf that is 23 karats or higher does not require sealing when applied to exterior surfaces. This high karat gold is inherently resistant to tarnishing, as it contains minimal amounts of silver or copper. In contrast, gold leaf with less than 23 karats contains higher proportions of these metals, making it susceptible to oxidation and tarnishing, thus necessitating a protective clear coat sealer.

We generally advise against sealing gold leaf in outdoor settings. Sealers, while protective, are prone to degradation—often becoming milky or hazy within 3 to 5 years. If left unsealed, gold leaf of 23 karats or higher can remain vibrant and intact for 20 to 30 years, provided it has been properly applied and maintained.