1. Observation of Cross-Sectional Crystallization

　　Premium slab: The cut surface exhibits a fine, dense crystalline structure (reminiscent of marble veining) with no grayish or dark inclusions.

　　Low-quality board: rough cross-section with porosity, often containing organic fillers such as wood shavings or straw.

　　2. Surface Flatness Test

　　Use a 2-meter straightedge for inspection; the gap between premium panels shall be ≤1 mm (national standard: ≤2 mm).

　　The diagonal deviation shall be less than 3 mm/m (Greenzhe’s measured value is 0.8 mm/m).

　　3. Percussion-based pitch identification method

　　High-quality board: The metallic tapping sound is crisp (frequency > 4000 Hz).

　　Low-quality panels: muffled sound (due to internal voids or uneven density).

　　4. Bending Test

　　High-quality panels (such as Lüzhe): With a 1-meter cantilever span, they can support 80 kg without cracking.

　　Low-quality board: Cracks appear when bent to 30°.

　　5. Water Absorption Test

　　Water‑drop test: On a high‑quality panel, water droplets exhibit the lotus‑leaf effect (contact angle > 100°).

　　After 24 hours of soaking, the water absorption and weight gain should be less than 3% (national standard: ≤8%).