GILDING

Water gilding traditionally uses 24-karat gold leaf, but let’s take a comprehensive look at the materials and tools required for the process:
- Water: First and foremost, all these materials are prepared using simple tap water.
- Rabbit skin glue: Essential for preparing the base.
- Bologna chalk (gesso): Used for creating the foundational surface.
- Natural bole: Yellow or red if applying gold leaf, or black for silver.
- Fish glue: For additional adhesion and finishing.
- 24-karat gold leaf: The main decorative element.

As for equipment:
- Gilder’s cushion and knife Gilder’s flat brush
- Soft brushes, including one specifically for applying bole
- Burnishers made of agate stone, in various shapes
- Electric heater
- Gilder’s pot
- Various containers

Sifting and Preparing Bologna Chalk

The gesso base must be built layer by layer, with each application varying slightly in composition. Here's how to proceed:

Step 1: Sifting Bologna Chalk
- Why sift the chalk? Bologna chalk is a hygroscopic material that absorbs moisture over time, forming clumps. These must be removed before mixing with the glue solution, as dissolving clumps directly in the mixture is challenging.
- Sifting aerates the chalk, improving its wettability when mixed with the glue solution.
Step 2: Preparing the Gesso Mixture
1. Start with the same diluted rabbit skin glue (“colletta”) used for sealing.
2. Gradually add the sifted chalk to the glue, allowing it to hydrate properly. Add small amounts at a time to ensure even mixing and avoid lumps.
Step 3: Applying Gesso Layers
1. First Layer:
- Apply the initial gesso mixture evenly over the surface. Allow it to dry thoroughly.
2. Subsequent Layers:
- Increase the amount of chalk in the mixture progressively for each new layer.
- Let each layer dry completely before adding the next.
3. Final Sanding:
- Once all layers are applied and fully dried, sand the surface using 240-grit sandpaper.
- Aim for a smooth, compact, and soft finish, ready for the next steps.

Key Notes
The preparation of the gesso base is critical for achieving a flawless water gilding finish. Take the necessary time for proper drying and ensure each layer is applied carefully to create a durable, even foundation.

Applying the Bole

After completing the gesso base, the next step in water gilding is applying the bole. Here's how to proceed:

Step 1: Preparing the Bole Mixture
- Combine bole with warm rabbit skin glue (“colletta”) at a ratio of 300 g of bole per 1 kg of colletta, creating a brushable liquid.
- What is bole?
Bole is a natural clay that serves several important functions in the gilding process:
1. Seals the gesso layer: Prevents the subsequent glue application from being fully absorbed.
2. Provides a colored base: Enhances the appearance of the metal leaf:
- Yellow: For a classic gold finish.
- Red: For an antique gold effect.
- Black: For silver.
3. Burnishing layer: Can be polished with an agate stone for added brilliance.
4. Adhesive property: Bole reactivates when moistened, becoming tacky to hold the metal leaf.

Step 2: Applying Bole Layers
1. Application:
- Apply 2–3 coats of the bole mixture with a light, precise touch, ensuring even coverage over the sanded gesso base.
- Use a crosshatch technique (alternating brush directions) to achieve uniform results.
2. Drying:
- Allow each coat to dry fully before applying the next.
3. Optional Burnishing:
- Once dry, the bole can be polished with an agate burnisher to enhance its smoothness and brilliance, preparing it for optimal gold leaf application.

Step 3: Preparing the Fish Glue
- Like rabbit skin glue, fish glue should be soaked in cold water until swollen, then dissolved in warm water.
- Dilute at a ratio of 1 part fish glue to 10 parts water. This solution will be used later in the gilding process.

With these steps, the surface is now ready for the final stage: applying the gold leaf.