How to avoid color differences and ensure color consistency between batches when solid color bricks are fired at high temperatures?
Release Time : 2026-02-27
Color difference remains a core challenge affecting product consistency during the high-temperature firing process of solid color bricks. Its root cause can be traced back to subtle differences in raw materials, processes, equipment, and environment, requiring systematic control to achieve color stability.
The stability of raw materials is fundamental to controlling color difference. The coloring substances in solid color bricks primarily rely on the ratio of pigments to base white pigments. Fluctuations in the content of components such as iron oxide and titanium oxide in different batches of raw materials directly lead to differences in base whiteness, thus affecting the depth of the final color. For example, a 0.1% increase in the iron content in kaolin can result in a noticeably darker brick after firing. Therefore, stabilizing the source of raw materials, rigorously testing the chemical composition of each batch, and neutralizing batch differences through premixing processes are the primary steps to avoid color difference.
The uniformity of the mixing of pigments and white pigments directly affects color distribution. The particle size, gradation, and ratio of pigments to white pigments must be precisely controlled. If the pigment particles are too coarse, color spots are easily formed after firing; if the ratio is off, the overall color will be either too dark or too light. During production, ball milling is used to refine the pigment particles, and electronic scales are employed for precise batching to avoid human error. Furthermore, the condition of the mixing equipment is crucial; powder buildup or localized blockages on the inner wall of the double-spiral mixer can lead to uneven mixing, requiring regular cleaning and maintenance.
The firing regime is a key factor determining color consistency. Fluctuations in temperature, atmosphere, and pressure within the kiln significantly alter the brick's color. For example, excessively high temperatures may cause pigment decomposition, resulting in a lighter color; an overly strong reducing atmosphere may cause the brick surface to appear bluish. To minimize variations, standardized firing curves must be developed, controlling the heating rate, holding time, and cooling speed. Simultaneously, the lateral temperature difference within the kiln must be minimized by adjusting parameters such as fan exhaust and combustion air supply to prevent color differentiation between the middle and sides of the product. For large-tonnage kilns, the burner layout must also be optimized to ensure a uniform thermal field.
Equipment precision and stability are equally important for color difference control. The forming pressure of the press directly affects the density of the brick blank; pressure fluctuations can lead to differences in surface roughness, thus affecting the uniformity of the color after firing. When multiple presses operate simultaneously, uniform pressing parameters must be maintained to avoid color variations within the same batch of products due to equipment differences. Furthermore, the printhead voltage, ink batch, and mixing uniformity of inkjet printers must be strictly monitored to prevent localized color deviations caused by uneven inkjet printing or ink sedimentation.
Detailed management during the production process is also crucial. For example, during spray drying of powder, changes in slurry moisture, viscosity, or nozzle diameter can lead to fluctuations in powder particle size and gradation, affecting the fabric application and final color. Blockages in the feed pipe or uneven grid surfaces can cause powder accumulation, resulting in unstable brick patterns. These details must be avoided through regular equipment inspections, pipe cleaning, and process parameter adjustments.
Batch management is the last line of defense for ensuring color consistency. In solid color brick production, even products of the same color code may exhibit slight color differences due to variations in firing time, kiln location, etc. Therefore, a color code system must be used to classify products from different production times, and color code information must be labeled on the packaging. Before installation, workers must sort the products by color number to avoid mixing products from different batches, thereby minimizing visual color differences.
Controlling color difference in solid color bricks is a comprehensive project involving raw materials, processes, equipment, environment, and management. From the chemical stability of raw materials to the precise execution of the firing process, from high-precision equipment maintenance to strict control of production details, every step must aim to eliminate variables. Only through systematic control and standardized operations can the long-lasting consistency of solid color brick color under high-temperature firing be achieved, meeting the market's demand for high-quality products.