Appearance quality inspection
1.Observation of Glazed Surface
High quality glaze should be smooth and flat, without pinholes, bubbles or spots, and should have a natural and transparent feeling when illuminated by light. The inner wall smoothness should meet industrial standards.
Uniformity of color glaze: The color of the monochrome Ceramic Colored Coffee Mug should be pure and free of impurities (such as sky blue or plum blue), and the gradient glaze should transition naturally without rigid boundaries.
2.Touch testing
Touching the glazed surface with hands should be as delicate as baby skin, with no burrs or bumps on the edges.
Knocking cup body test: High quality cups are as clear as wind chimes (bone china) or as thick as muffled drums (stoneware), while low or hoarse sounds may indicate hidden cracks or uneven density
Process quality identification
1.Bonding degree between glaze layer and matrix
Check if the glaze is tightly bonded to the cup body, without any glaze cracking or peeling, which can be verified by soaking in white vinegar for 2 hours: bubbling or discoloration indicates poor stability of the glaze.
Observing the details of the cup mouth, handle, etc.: Insufficient firing temperature can cause the glaze surface to become dull, while high-temperature glaze (≥ 1200 ℃) firing results in a denser texture of the colored glaze cup.
2.Identification of Glazing Process
Priority should be given to underglaze colored ceramic mug (with patterns underneath the glaze layer), which have no unevenness when touched and are safer than overglaze colored cups (where pigments come into direct contact with liquids).
The painted part should have clear lines, high color fastness, and pass the friction test (wiped with a white cloth) without fading, which is considered a qualified product
