Glazing is far more than just “applying a layer of glaze” — it is the first step that determines a vase’s texture, color, and functionality.

1. The Magical Transformation of Glaze Materials

Raw Materials: Different mineral compositions create infinite possibilities. For example:

• Feldspathic glaze is transparent and bright, forming the basis of most daily-use ceramics
• Lime glaze is warm and jade-like, the soul of celadon porcelain
• Ash glaze (made from plant ash) is rustic and natural, with a random aesthetic quality
• Metal oxides (such as iron, copper, cobalt) determine glaze colors — iron turns celadon or black, copper turns red or green, cobalt turns blue

Microstructure of the Glaze Layer: After firing, the glaze layer can be:

• Transparent — allowing the color or painting of the clay body beneath to show through
• Opaque — like a thin veil or paint, completely covering the clay body
• Crystalline — beautiful mineral crystals (like snowflakes or pine needles) grow during cooling

2. Glazing Techniques and Their Effects

Dip Glazing: The vase is immersed into the glaze slurry. The duration and technique (fast or slow, single or multiple dips) all affect the glaze thickness, which in turn influences the final color and texture. Fingerprint marks (unglazed spots from handling) are evidence of handmade production.

Swing Glazing: Glaze slurry is poured into the bottle and swirled to evenly coat the interior walls. This method is commonly used for vases with a wide belly and narrow mouth. Interior glazing is essential for water-holding vases, as it prevents liquid leakage and bacterial growth.

Pour Glazing: Glaze slurry is poured over the vase body using a ladle or spout. This method suits large pieces or those that cannot be directly dipped. The flowing marks often create unique artistic effects.

Spray Glazing/Brush Glazing: As mentioned earlier. Note that brush glazing leaves obvious brushstroke textures, which some artists deliberately use to create abstract styles.

Advanced Decorative Techniques

1. Layered Painting and Firing Temperatures

This is key — it determines the durability and safety of the pattern.

Underglaze Painting: Painting on the unglazed clay body, then covering with a transparent glaze and firing at high temperature in one go (approx. 1200–1400°C). The pigments penetrate into the clay body and fuse with the glaze layer.

• Advantages: Smooth, glossy surface; never wears off or fades; lead-free and non-toxic; safest option. Represented by: Blue-and-white porcelain, Underglaze red, Underglaze five-color.
• Disadvantages: Some colors may change or burn off at high temperatures; fewer color varieties than overglaze.

Overglaze Painting: First firing a vase with a plain white glaze surface (called “bisque porcelain”), then painting on it with low-temperature pigments (approx. 600–900°C), followed by a second firing. The pigments float on the glaze surface.

• Advantages: Extremely rich and vibrant colors; can create very fine and complex images (e.g., gongbi figures, oil painting styles). Represented by: Famille rose, Famille verte, Enamel colors, New colors.
• Disadvantages: Pigments sit on the surface; prolonged rubbing or exposure to acids/alkalis may cause wear. For food vessels (bowls, plates), overglaze has lead/cadmium leaching risks, but for vases used as ornamentation or hydroponic planters, this risk is negligible. Modern environmentally friendly overglaze has greatly reduced this issue.

In-glaze Painting: A hybrid approach. Painting on the bisque-fired body, then applying a thin glaze, or painting directly on the glaze surface, followed by high-temperature rapid firing that allows pigments to penetrate into the glaze layer.

• Advantages: Combines the safety and durability of underglaze with the vibrant richness of overglaze; the surface remains smooth. Commonly found in high-end daily-use ceramics.

For vases: All three painting methods are common. For flower arranging or holding water, underglaze and in-glaze are perfect choices. Overglaze vases are fine — just avoid scratching the surface with hard objects.

2. The Evolution of Decal Transfers

Small-film decals are currently the mainstream technology, replacing earlier hand-applied large decals. They can achieve camera-level precision and rich colors — more consistent and cheaper than hand painting. However, their drawbacks include:

• Upon close inspection, you can sometimes see a dot matrix structure (similar to enlarged newspaper photos), lacking the brushstrokes and tonal variations of hand painting.
• Poor application may result in bubbles or curled edges (on inferior products).

Identification tip: Use a magnifying glass to examine the pattern. If you see regular fine dots, it’s a decal; if you see continuous brushstrokes with variations in pigment depth, it’s hand-painted.

Modern Cutting-Edge Techniques

1. Vacuum Coating (PVD) — A Deeper Analysis

This is undoubtedly the current representative of luxury in ceramic vases. The process:

1. First, create a ceramic vase with a perfect surface coated with a transparent base glaze (typically dark colors like deep blue, black, or burgundy to complement the coating).
2. Place it in a vacuum chamber, evacuate the air, and introduce inert gas.
3. Use high voltage to ionize metal targets (such as titanium, chromium, zirconium) into metal ions.
4. The ions fly at high speed toward the vase surface under an electric field, depositing to form a nanometer-thick metal film.

The results are stunning: it can be a brilliant mirror-like gold, rose gold, silver, or effects like black titanium or “sapphire blue,” “emerald green” (achieved through multiple different metal films or reactions with other gases).

Advantages: Extremely wear-resistant, acid/alkali-resistant, non-fading (because it’s not just a color applied to the surface but forms a metal compound layer), easy to clean — restores shine with a damp cloth. However, the process is complex and costly, typically found in high-end brands or art pieces.

2. Digital Spray Glazing and 3D Printing

This is the future trend. Using industrial piezoelectric printheads (similar to printers), specially formulated ceramic ink or glaze is sprayed directly onto the clay body. This enables:

• Photo-grade image precision (resolution and realism far exceeding ordinary decals)
• Creation of three-dimensional凹凸 surfaces: By layering white or colored slurry, “printing” relief textures directly onto the vase surface
• Mold-free personalization: 3D printing the vase body itself, then applying glaze decoration on its surface

Special Surface Effect Treatments

Crackle Glaze & Craquelure: Intentionally exploiting the different shrinkage rates between glaze and clay body, causing the glaze layer to crack during cooling, forming “ice cracks” or “golden threads and iron lines” (as seen in Ge ware ceramics). The cracks can be colored and become decorative elements.

Kiln Transformation (Yaobian): At high temperatures, metal oxides in the glaze undergo uncontrollable flow and chemical reactions, producing fantastical, unreproducible colors and textures (like Jun ware’s “one color into the kiln, ten thousand colors out”). This is natural art.

Grinding & Polishing: Applied to the bisque body (after bisque firing) or after glazed firing. Bisque grinding smoothens the clay body; post-firing grinding can achieve:

• Matte finishing: Grinding a glossy glaze surface into a uniform matte texture
• Bare clay effects: Locally grinding away the glaze layer to reveal the white or colored clay body beneath, creating contrasting decoration

Chemical Coloring: Brushing metal salt solutions (e.g., copper sulfate, potassium permanganate) onto unglazed bisque-fired bodies, allowing them to penetrate and undergo chemical reactions to produce colors. Can create antique effects like verdigris green or rust brown.

💡 Summary Table: Techniques & Appreciation Guide