Sodium hexametaphosphate (SHMP) is widely used in the ceramic industry as a dispersant, water reducer, and process aid. When properly applied, it helps optimize slurry rheology, improve glaze behavior, and enhance decorative performance. This article summarizes how SHMP works in ceramic production and what technicians should consider when using it in tile, sanitary ware, and other ceramic plants.
For a broader view of industrial phosphate applications, see our industrial phosphates and chemicals overview, where SHMP is one of the key products discussed.
How SHMP Works in Ceramic Systems
In ceramic bodies and glazes, SHMP functions primarily as:
- Deflocculant and dispersant – it helps separate particles, reduce viscosity, and improve slurry flow.
- Water reducer – enables lower water content at the same or better fluidity, supporting higher density and lower drying shrinkage.
- Chelating agent – complexes calcium and other metal ions that may negatively affect stability.
These effects directly influence casting, pressing, drying, and firing behavior, with a significant impact on final product quality and process efficiency.
SHMP in Ceramic Slurry and Porcelain Body
In body slips and porcelain mud, SHMP is used in small dosages to achieve a balance between fluidity and suspension stability:
- Reducing slurry viscosity makes pumping, mixing, and casting easier.
- Allowing reduced water content, which improves green density and can shorten drying time.
- Helping to maintain a uniform solid distribution in storage and circulation tanks.
Typical dosages are low (often well below 0.5% on dry solids), and the optimum level depends on clay type, body formulation, solid content, and interaction with other additives such as water glass or polymeric dispersants. Overdosing can cause excessive deflocculation, sedimentation, or poor suspension, so plant trials are essential.
SHMP in Glaze Formulations
In glaze systems, SHMP helps control glaze rheology and application behavior. Key benefits include:
- Smoother flow and more stable viscosity during spraying or dipping.
- Improved leveling and reduced defects such as pinholes or orange peel.
- Better control over glaze thickness and coverage.
- Enhanced adhesion and surface quality after firing.
By reducing the tendency of glazes to thicken or settle, SHMP supports consistent appearance and gloss across production runs.
Water Reduction and Cost Optimization
Compared with using water glass or other inorganic dispersants alone, SHMP often achieves better water-reducing performance at lower total additive cost. Combined systems, where SHMP is used together with traditional silicate water reducers or modern polymer dispersants, can offer:
- Improved flow time at reduced water content.
- Higher solids loading with acceptable viscosity.
- Better compromise between fluidity, stability, and green strength.
Each plant must optimize the ratio between SHMP and other dispersants based on raw materials, equipment, and target product quality.
Role of SHMP in Ceramic Decoration
In ceramic decoration, SHMP can be used in printing pastes and engobes to help control viscosity and pigment dispersion. Benefits include:
- More uniform color distribution.
- Improved adhesion between decorative layers and the substrate.
- More stable printing or spraying behavior over long production runs.
Because SHMP influences rheology and particle interaction, small adjustments can have visible effects on decorative quality. Technicians should monitor printing line performance and adjust dosage carefully.
Dosage and Practical Use Considerations
When using SHMP in ceramic plants, several practical points are important:
- Start with low dosages and increase gradually while monitoring viscosity and flow time.
- Dissolve SHMP properly before addition to ensure uniform distribution.
- Evaluate interactions with other additives, especially water glass, polymer dispersants, and binders.
- Monitor slurry behavior over time, including storage stability and re-dispersion after rest.
Because raw materials and process conditions vary significantly between plants, on-site trials remain the best way to confirm the ideal dosage range.
Working with Goway Chemical on SHMP for Ceramics
Goway Chemical supplies industrial-grade sodium hexametaphosphate for ceramic and other technical applications. We can provide guidance on grade selection, suggested dosage ranges, and interaction with other dispersants based on your specific body and glaze formulations.
If you are exploring process optimization, reducing water usage, or improving slip stability, our team is available to review your current formulation and propose appropriate SHMP-based solutions.
Frequently Asked Questions
What is the typical dosage of SHMP in ceramic slurry?
Dosage levels vary by body formulation and raw material, but they are generally low, often below 0.5% on dry solids. Trials are required to find the optimal balance between fluidity and suspension stability.
Can SHMP replace water glass completely?
In many plants, SHMP is used together with water glass or polymer dispersants rather than as a complete replacement. The best performance usually comes from a balanced combination tailored to the specific body or glaze.
Does SHMP affect fired color or glaze appearance?
When used at appropriate levels, SHMP is primarily a process aid and should not significantly change fired color. Its main impact is on rheology, leveling, and defect reduction. As with any additive, trials are necessary to confirm visual results in your specific system.
Can the same SHMP grade be used for both slurry and glaze?
In many cases, yes, but requirements for dissolution and handling may differ. We can recommend suitable grades for plants that wish to use SHMP in multiple stages of ceramic production.
