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What is CMC & PAC

Sodium carboxymethyl cellulose (CMC) is usually made by the reaction of natural cellulose and caustic soda and a chlorine acetic acid made after the production of an anionic polymer.

It is cellulose carboxymethyl ether sodium salt, an anionic cellulose ether, white or milky white fibrous powder or granules. CMC can be widely used in various industries, for example Food, Pharm, Ceramic, Textile, Paint, Paper-making, Detergent etc.

The international community to this new type of modified CMC also known as “polyanionic cellulose (abbreviated PAC)”. PAC is typically used in Oil drilling industry.

Ceramic Grade

Ceramic Grade

THE FUNCTION OF CMC IN THE CERAMIC INDUSTRY
CMC can be applied as excipient and plasticizer for ceramic body. With appropriate proportion, the adhesive force of the body material could be increased which could make the ceramic easier to form. This application can also improve the stability of ceramic body and promote the rate of superior ceramic products.

For glaze body, CMC can improve the surface tension and make the dispersion more stable. Besides, the surface of glaze will be more smooth and the phenomenon of glazed pinhole after sintering will also be well controlled.

IN CERAMIC BODY
  • Binder: CMC enhances the bonding force between body particles, improving dry flexural strength and preventing cracking or breakage during shaping or handling, particularly in plastic molding or dry pressing processes.
Alternative to Traditional Binders: Partially replaces more expensive binders like Polyvinyl  Alcohol (PVA) or starch, reducing costs.
  • Water Retainer: Slows down the drying rate of the body, minimizing cracks caused by uneven moisture gradients (especially in large or complex-shaped pieces).
Adjusting the CMC dosage (typically 0.1%-0.5%) allows control over drying shrinkage.
  • Suspension Stabilizer: In slip casting, it prevents sedimentation of solid particles, ensuring uniform composition and improving fluidity.
  • Plasticity Enhancer: Increases the plasticity of the body, facilitating hand-forming techniques like throwing or carving.

IN CERAMIC GLAZE
  • Rheology Modifier: Imparts pseudoplasticity (shear-thinning behavior) to glaze slurries, making them easy to spray or dip during application while preventing sagging once the force is removed.
  • Alternative to Bentonite: Reduces the need for mineral thickeners in some formulations.
  • Anti-Settling Agent: Maintains the suspension of high-density materials (e.g., zinc oxide) in the glaze, preventing stratification.
  • Binder: Improves adhesion between the glaze layer and the body, reducing the risk of peeling before firing.
  • Color Homogenizer: Promotes even distribution of colorants, minimizing defects like spots or streaks on the glazed surface