Color Matching Techniques for Colorful Coatings
Color matching of colorful coatings refers to matching colored particles of dispersed phase,
so as to achieve realistic marble-like effect via spray gun construction.
To ensure high simulation effect,
proper collocation of colors and particle sizes is the core key.
Color matching includes selection and matching of base coat color,
as well as color and size matching of particles in continuous phase.
Selection and Matching of Matching Base Coat
Before mass production, confirm the color sample with the client first and determine the matching base color, which is the overall visual hue of the sample from a distance.
A proper matching base color not only enhances the final marble simulation effect of colorful paint, but also reduces the consumption of topcoat. It shall be coordinated with the main color of particles without excessive color contrast. In addition, the tuned base color is preferably slightly lighter than the actual color shown on the sample.
Color Configuration of Colorful Particles
Discharging of base paint for HSJA system water-in-sand coating Excellent fluidity after sand addition
Before mass production, select base materials with different titanium dioxide contents according to the shade of colored particles on the sample. Use 0% titanium dioxide base material for transparent and semi-transparent particles, and 1% titanium dioxide base material for high-opacity solid-color particles. Intermediate hues can be blended with these two base materials. Calculate the dosage strictly based on sample standards and adjust colors little by little until the particle color matches the sample perfectly.
In terms of color paste selection, iron-based inorganic color pastes are preferred, while bright organic color pastes should be used sparingly. Firstly, natural marble rarely has vivid hues, so bright organic pastes are unnecessary. Secondly, organic color pastes feature high oil absorption and require large amounts of surfactants during grinding, which will impair the stability of particles in the continuous phase. Thirdly, inorganic color pastes deliver superior weather resistance and effectively extend the service life of colorful coatings.
Furthermore, limit the types of particle colors to 5 to 7 kinds appropriately. Too few colors fail to present natural marble layered texture, while excessive colors increase workload and make color re-production difficult in supplementary production, thus lowering production efficiency. Especially for water-in-sand coatings, high-quality coating systems feature low viscosity for easy color mixing and outstanding fluidity of base paint after sand addition, enabling convenient large-scale production.
Selection and Collocation of Colorful Particle Sizes
There are two main granulation processes for colorful coatings. The first is direct granulation with a disperser equipped with a special turntable. Different sizes of colored particles are obtained by adjusting rotating speed. This method requires skilled operation and stable coating performance, and produces particles with high simulation effect. The second is granulator granulation, which is widely applied in mass production for easier operation. High-quality colorful coating systems are compatible with both granulation methods, and the granulated particles of water-in-sand coatings are free from sedimentation for smooth production.
The size and distribution of colored particles are determined according to actual sample requirements. Firstly confirm the dosage of large particles of 10-20 mesh, then set the mesh number and quantity of fine dark speckle particles. Other auxiliary color particles generally adopt about 40 mesh. It is recommended to compare colors on the base coat after color blending, as most semi-transparent colored particles show different hues against different base colors.
Spraying Skills for Colorful Coatings
Special spray guns are mandatory for colorful coating construction, which consist of an ordinary spray gun matched with a pressure feed tank connected via flexible hoses. Common tank capacities are 2L and 10L. For small-area construction, place a 1L inner bucket inside the 10L tank to reduce material waste.
A vent valve is fitted on the tank cover. Before feeding materials, turn off the air inlet switch first, pull up the vent ring to exhaust residual compressed air inside the tank, and open the tank for feeding only after the pressure gauge returns to zero.
An air intake regulating valve is also equipped on the tank cover to adjust air pressure and control discharging speed. Adjust the pressure according to particle size: lower pressure for large particles and higher pressure for fine particles. The optimal working pressure is controlled within 0.06~0.1 MPa. Spray guns with nozzle diameter of 3.5mm to 4.0mm are commonly used.
Three adjustment knobs are installed on the spray gun. The first one adjusts spray fan width to control spraying coverage area. The second controls paint output by changing the gap between needle and nozzle; the closer the needle is to the nozzle, the smaller the flow rate and the finer the sprayed particles, and vice versa. It is usually fixed well in advance without repeated adjustment. The bottom knob regulates spraying air pressure. Insufficient pressure leads to incomplete particle spreading and poor pattern effect; excessive pressure easily breaks particles and causes irregular tail-shaped patterns on walls.
Keep the distance between spray gun and wall at 30 to 40 centimeters. Excessive distance causes sagging and poor particle spreading; too short distance results in broken particles and deformed patterns. Keep continuous spraying for one-step forming and minimize spot spraying and supplementary spraying.
After construction, thoroughly clean the spray gun. Do not tighten the pressure tank cover too tightly during storage to avoid premature damage of sealing gaskets.