You make gold leaf shine primarily through a process called burnishing.
Burnishing Explained
Burnishing involves using a specialized tool, most commonly an agate burnisher, to aggressively rub the surface of the gold leaf. This action doesn't just polish the surface; it compresses the underlying "bole," which is a clay-like substrate prepared before applying the gold leaf. This compression is key to achieving a high shine.
Steps for Burnishing Gold Leaf
While the fundamental principle is simple, the execution requires care and a proper setup. Here's a breakdown:
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Gilding Preparation: The surface must be properly gilded beforehand. This includes applying a suitable adhesive (size) or bole, depending on the desired finish. Using a water gilding technique with a clay bole base is essential for achieving the highest shine.
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Drying Time: Allow the bole and gold leaf sufficient time to dry completely. The drying time will vary depending on the humidity and materials used.
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Burnishing Tool: Use an agate burnisher. Agate is a smooth, hard stone that won't scratch the gold. Different shapes and sizes are available depending on the detail and complexity of the gilded object.
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Burnishing Technique: Apply firm, consistent pressure with the burnisher and rub in a smooth, overlapping motion. The pressure compresses the bole beneath the gold leaf, creating a reflective surface. Work systematically, covering the entire surface.
Why Burnishing Works
The shine achieved through burnishing comes from two main factors:
- Smoothing the Gold Surface: Burnishing physically flattens any microscopic imperfections in the gold leaf, creating a smoother, more reflective surface.
- Compressing the Bole: Compressing the bole substrate underneath the gold leaf hardens and polishes the bole itself. This hard, polished bole then reflects light back through the incredibly thin gold leaf, greatly enhancing its brilliance.
Alternatives to Burnishing
While burnishing is the most common method for achieving a high shine on gold leaf, other polishing techniques might be used in specific situations. However, these alternatives generally do not produce the same level of brilliance:
- Soft Cloth Polishing: Using a very soft cloth to gently buff the gold leaf can improve its luster slightly, but it won't compress the bole. This is often used on oil gilded surfaces.
Key Considerations for a Brilliant Shine
- Bole Preparation: A properly prepared bole is crucial. The bole must be smooth, even, and properly dried.
- Gold Leaf Quality: The quality of the gold leaf itself impacts the final result. Higher karat gold is typically softer and burnishes more easily.
- Practice: Burnishing is a skill that improves with practice. Mastering the correct pressure and technique takes time.
