In the ceramic production process, the viscosity of the glaze slurry is a very important parameter, which directly affects the fluidity, uniformity, sedimentation and final glaze effect of the glaze. In order to obtain the ideal glaze effect, it is crucial to select the appropriate CMC (Carboxymethyl Cellulose) as a thickener. CMC is a natural polymer compound commonly used in ceramic glaze slurry, with good thickening, rheological properties and suspension.
1. Understand the viscosity requirements of the glaze slurry
When selecting CMC, you first need to clarify the viscosity requirements of the glaze slurry. Different glazes and production processes have different requirements for the viscosity of the glaze slurry. Generally speaking, too high or too low viscosity of the glaze slurry will affect the spraying, brushing or dipping of the glaze.
Low viscosity glaze slurry: suitable for spraying process. Too low viscosity can ensure that the glaze will not clog the spray gun during spraying and can form a more uniform coating.
Medium viscosity glaze slurry: suitable for dipping process. Medium viscosity can make the glaze evenly cover the ceramic surface, and it is not easy to sag.
High viscosity glaze slurry: suitable for brushing process. High viscosity glaze slurry can remain on the surface for a long time, avoid excessive fluidity, and thus obtain a thicker glaze layer.
Therefore, the selection of CMC needs to match the production process requirements.
2. Relationship between the thickening performance and viscosity of CMC
The thickening performance of AnxinCel®CMC is usually determined by its molecular weight, degree of carboxymethylation and addition amount.
Molecular weight: The higher the molecular weight of CMC, the stronger its thickening effect. A higher molecular weight can increase the viscosity of the solution, so that it forms a thicker slurry during use. Therefore, if a higher viscosity glaze slurry is required, a high molecular weight CMC should be selected.
Degree of carboxymethylation: The higher the degree of carboxymethylation of CMC, the stronger its water solubility, and it can be more effectively dispersed in water to form a higher viscosity. Common CMCs have different degrees of carboxymethylation, and the appropriate variety can be selected according to the requirements of the glaze slurry.
Addition amount: The addition amount of CMC is a direct means to control the viscosity of the glaze slurry. Adding less CMC will result in a lower viscosity of the glaze, while increasing the amount of CMC added will significantly increase the viscosity. In actual production, the amount of CMC added is usually between 0.5% and 3%, adjusted according to specific needs.
3. Factors affecting the selection of CMC viscosity
When selecting CMC, some other influencing factors need to be considered:
a. Composition of glaze
The composition of the glaze will directly affect its viscosity requirements. For example, glazes with a large amount of fine powder may require a thickener with a higher viscosity to maintain good suspension. Glazes with less fine particles may not require too high a viscosity.
b. Glaze particle size
Glazes with higher fineness require CMC to have better thickening properties to ensure that the fine particles can be evenly suspended in the liquid. If the viscosity of CMC is insufficient, the fine powder may precipitate, resulting in uneven glaze.
c. Water hardness
The hardness of water has a certain effect on the solubility and thickening effect of CMC. The presence of more calcium and magnesium ions in hard water may reduce the thickening effect of CMC and even cause precipitation. When using hard water, you may need to choose certain types of CMC to solve this problem.
d. Working temperature and humidity
Different working environment temperatures and humidity will also affect the viscosity of CMC. For example, in a high temperature environment, water evaporates faster, and low-viscosity CMC may be needed to avoid over-thickening of the glaze slurry. On the contrary, a low-temperature environment may require a higher viscosity CMC to ensure the stability and fluidity of the slurry.
4. Practical selection and preparation of CMC
In actual use, the selection and preparation of CMC need to be carried out according to the following steps:
Selection of AnxinCel®CMC type: First, select the appropriate CMC variety. There are different viscosity grades of CMC on the market, which can be selected according to the viscosity requirements and suspension requirements of the glaze slurry. For example, low molecular weight CMC is suitable for glaze slurries requiring low viscosity, while high molecular weight CMC is suitable for glaze slurries requiring high viscosity.
Experimental adjustment of viscosity: According to the specific glaze slurry requirements, the amount of CMC added is experimentally adjusted. The common experimental method is to gradually add CMC and measure its viscosity until the desired viscosity range is reached.
Monitoring the stability of the glaze slurry: The prepared glaze slurry needs to be left to stand for a period of time to observe its stability. Check for precipitation, agglomeration, etc. If there is a problem, the amount or type of CMC may need to be adjusted.
Adjust other additives: When using CMC, it is also necessary to consider the use of other additives, such as dispersants, leveling agents, etc. These additives may interact with CMC and affect its thickening effect. Therefore, when adjusting CMC, it is also necessary to pay attention to the ratio of other additives.
The use of CMC in ceramic glaze slurry is a highly technical task, which requires comprehensive consideration and adjustment based on the viscosity requirements, composition, particle size, use environment and other factors of the glaze slurry. Reasonable selection and addition of AnxinCel®CMC can not only improve the stability and fluidity of the glaze slurry, but also improve the final glaze effect. Therefore, continuously optimizing and adjusting the use formula of CMC in production is the key to ensuring the quality of ceramic products.
Post time: Jan-10-2025