Why a whiter kaolin powder may not brighten the finished product

Can calcined kaolin replace water-washed kaolin at equal weight?

Brightness, oil absorption, particle size and dispersion all affect the finished product. A dry-powder color comparison cannot establish finished-part appearance.

Compare color on equal-thickness specimens

Use the same resin or coating base, filler basis, mixing method and thickness. Record color and surface defects, then compare viscosity or processing load.

Why could a whiter powder give a darker finished part?

Check dispersion under shear, resin colour and process temperature in the same formulation. Mineral fillers in plastics: In the same polymer, compare dispersion, surface gloss and impact resistance. Rubber filling: Compare mixing torque, cure curve and mechanical properties.

Checking Particle size distribution and Oil absorption

Particle size distribution (µm): Report D50, the coarse end of the distribution and the dispersion conditions for measurement. Oil absorption (g/100 g): Compare using the same method and investigate differences in porosity or processing. Whiteness or brightness (Specified scale): State the equipment used and whether the material is calcined.

What to record

• Physical form
• Filler basis
• Sheet thickness
• Color
• Processing load

Technical references

• Burgess Pigment: grade-specific kaolin data ↗

Products and processes