Optimizing Slurry Density in Fiber Cement Production: A Deaeration Solution Based on INVINO-8082A

In the production of fiber cement boards—whether utilizing the Hatschek process or Flow-on technology—engineers frequently encounter a paradox: the surface foam is suppressed, yet the final board still exhibits structural flaws such as delamination, surface pinholes, and inconsistent dry density.

The root cause is not surface foam, but Entrained Air. At INVINO, we have developed a high-performance solution centered on INVINO-8082A-TDS, specifically engineered to address the micro-bubbles trapped within dense fiber-cement matrices.

Traditional defoamers often focus on “knocking down” visible bubbles. However, in a cementitious slurry with high solid content and fibrous reinforcement, microscopic air bubbles become physically trapped.

If these bubbles are not released before the forming stage:

• Density Drop: Internal voids reduce the overall compact density of the board.

• Structural Weakness: Entrained air creates “weak points,” leading to reduced flexural strength and increased risk of delamination.

• Surface Defects: During the curing or pressing phase, these micro-bubbles migrate, causing “crater” defects or pinholes.

To solve the “deep air” problem, a defoamer must possess specific chemical properties that can withstand the harsh environment of cement hydration. INVINO-8082A is formulated as a 100% active, non-silicone deaerator.

• Zero Silicone/Mineral Oil Risk: Unlike silicone emulsions, 8082A does not suffer from “emulsion breakage” in high-pH environments. This eliminates the risk of “oil spots” and ensures excellent adhesion for post-production coatings or laminations.

• Molecular Deaeration: The modified polyether structure lowers the surface tension of the liquid-fiber interface, allowing entrained micro-bubbles to coalesce and escape rapidly.

• Concentrated Efficiency: With 100% active matter, 8082A offers a significantly lower cost-in-use compared to 20-30% active emulsions, reducing storage and logistics footprints.

Based on field data from various production lines, we recommend a strategic dosing approach to maximize deaeration efficiency:

• Slurry Preparation (Mixing Stage): Adding 8082A during the initial mixing phase prevents the stabilization of foam created by high-shear agitation.

• Headbox / Forming Section: This is the critical “Deaeration Zone.” 8082A facilitates the release of air from the slurry as it is distributed onto the wire, ensuring a dense and uniform mat formation.

• White Water Loop: 8082A maintains long-lasting anti-foaming properties, preventing the accumulation of air in the circulating water system, which reduces pump cavitation and improves drainage.

In comparative laboratory tests and field trials, INVINO-8082A has demonstrated a 3% to 5% improvement in slurry density compared to untreated batches.

Recommended Dosage:

• 0.1kg to 0.5kg per ton of finished board (dry weight).

• Note: Precise dosage should be determined via a standard “graduated cylinder shake test” or air entrainment meter using your specific fiber-cement slurry sample.