HPMC is a water-soluble polymer that is derived from cellulose, and it can be added to ceramic formulations as a powder or a liquid.
Some common uses of HPMC in ceramics include:
Binder: HPMC can be used as a binder to improve the green strength of ceramic bodies, which makes them less fragile and easier to handle during the forming process.
Suspension agent: HPMC can help to suspend solid particles in liquid glazes or slips, which improves their flow properties and prevents settling.
Plasticizer: HPMC can act as a plasticizer in ceramic formulations, which makes them more malleable and easier to shape during forming.
Anti-cracking agent: HPMC can help to prevent cracking and shrinkage in ceramic bodies during the drying process, which improves their overall quality.
Rheology modifier: HPMC can be used to adjust the viscosity and flow properties of ceramic slurries and glazes, which allows for better control over their application and performance.
Here is a general guideline on how to use HPMC in ceramics:
Determine the appropriate concentration: The optimal concentration of HPMC depends on the specific application and the properties desired in the ceramic formulation. Typically, HPMC is used at a concentration of 0.5-3% by weight of the ceramic slurry or glaze.
Mix HPMC with water: HPMC is generally added to the aqueous phase of the ceramic formulation. To disperse HPMC, it is important to mix it with hot water (around 60-80°C) to allow the polymer to hydrate and dissolve completely. It is recommended to add HPMC slowly and stir well to prevent clumping.
Add other ingredients: Once HPMC is well dispersed, other ingredients can be added to the ceramic formulation, such as clays, feldspars, kaolins, pigments, or other additives.
Adjust rheology and viscosity: HPMC can be used to adjust the rheology and viscosity of the ceramic slurry or glaze. The optimal viscosity and rheology depend on the specific application, but typically, HPMC can be used to increase the fluidity and reduce the settling of solid particles in the slurry or glaze.
Optimize for application: Once the ceramic formulation with HPMC is well mixed, it is important to test and optimize its application properties, such as casting, spraying, or brushing. This includes testing the flow, leveling, and drying properties of the formulation to ensure it meets the desired application standards.
HPMC (Hydroxypropyl methylcellulose) offers several advantages when used as an additive in ceramics, including:
HPMC can improve the workability of ceramic bodies and glazes, making them easier to shape, mold, and apply. This is because HPMC acts as a plasticizer, increasing the flexibility and reducing the stiffness of the materials.
HPMC can improve the green strength of ceramic bodies, which means they are less likely to crack or break during the handling and forming process. This is because HPMC acts as a binder, holding the particles together and increasing the strength of the materials.
HPMC can improve the suspension of solid particles in liquid glazes or slips, which makes them more consistent and easier to apply. This is because HPMC acts as a suspension agent, preventing the particles from settling and improving the flow properties of the materials.
HPMC can help to reduce shrinkage and cracking in ceramic bodies during the drying process. This is because HPMC acts as an anti-cracking agent, improving the plasticity and elasticity of the materials and reducing their tendency to crack or shrink.
HPMC can improve the application properties of ceramic slurries and glazes, making them easier to apply and control. This is because HPMC acts as a rheology modifier, adjusting the viscosity and flow properties of the materials.