How to Identify the Quality of Ceramic Bodies to Avoid Stains or Yellowing in Toilets?

When purchasing a toilet, many people focus on appearance, functionality, and flushing mechanisms, often overlooking the most crucial material—the ceramic body.

At first glance, ceramic bodies may seem indistinguishable. However, the ease of cleaning, as well as the issues of staining and yellowing, are directly related to the quality of the ceramic body.

The ceramic body primarily consists of two parts: the body and the glaze, comparable to the relationship between a tree trunk and its bark.

1. Raw Materials of the Ceramic Body

a. Place of origin
The origin of ceramics affects the quality of raw materials. China has eight major ceramic production bases: Foshan in Guangdong, Tangshan in Hebei, Chaozhou in Guangdong, Jingdezhen in Jiangxi, Dehua in Fujian, Zibo in Shandong, Liling in Hunan, and Yixing in Jiangsu. Among these, Foshan and Tangshan are particularly renowned, being hailed as the ceramic capitals of the south and the north respectively. Well-known toilet brands and manufacturers are primarily concentrated in these areas.

b.Raw Materials
The primary raw materials for ceramics include clay, feldspar, and quartz. Clay serves as the major binding agent, combining feldspar and quartz; feldspar acts as a flux, lowering the firing temperature of silica; quartz, with its high melting point, acts as a framework during firing.

This framework expands during firing, reducing shrinkage and improving the durability, strength, and chemical stability of both the body and glaze.

2. Firing Process

Once the body is formed, it needs to be fired in a kiln. Based on temperature, the kilns can be classified into low, medium, and high temperature.

a. Firing Temperature

Low Temperature Kiln: Approximately 700-900°C, with a firing time of around 8 hours.

Medium Temperature Kiln: Firing temperature ranges from 1000 to 1150 °C.

High Temperature Kiln: Firing temperature is above 1200°C. High-quality toilet ceramic bodies are fired in high-temperature kilns at 1280℃（2336℉ ）for more than 20 hours.

b.Ceramization
High-temperature kilns can thoroughly fire the entire body, yielding a translucent porcelain-like state. Higher temperatures create denser crystal structures in the glaze, removing impurities. Consequently, the resulting porcelain is not only whiter and purer but also has a low water absorption rate, making it easy to clean and resistant to odor absorption. In medium to low-temperature kilns, insufficient firing leads to porous materials with high water absorption, making them prone to yellowing and harder to clean. The fuel and raw material costs for high-temperature kilns exceed those of medium to low-temperature kilns, leading some small workshops to use lower-temperature firings to cut production costs.

3. Glaze

After the body is dried and fired, a layer of glaze must be applied to its surface and then fired again at high temperatures, forming a glass-like substance. The quality of the glaze is directly related to staining and yellowing issues. A high-quality glaze is hard, dense, scratch-resistant, and does not easily absorb dirt or yellow with extended use. So, how to tell whether the glaze is good or bad?

a.Examine the Glaze Finish
The type of glaze, including its mix ratios, varies among manufacturers. Generally, well-known sanitary ware manufacturers use imported boric acid which demands high purity. Under similar production conditions and process levels, glazes made with imported boric acid tend to have better gloss and fewer pores, resulting in reduced staining.

b. Look at the thickness of the glaze layer
A quality glaze should have a thickness exceeding 0.8 mm. High-quality glazes use glazing techniques that might include titanium dioxide and phosphates to increase density and whiteness, thereby improving light reflectivity.

When purchasing a toilet, examine the ceramic body for a smooth surface; a touch test can also be informative. The smoother and finer the feel, the better the quality of the glaze.

4. Anti-fouling test

The fundamental functions of a toilet lie in its flushing capability and stain resistance. How can one determine if a toilet meets these standards?

a.Artificial Stool Test
Place 20 artificial stools, each weighing 50 grams, into the toilet, activate the flushing mechanism, and count the number of artificial stools expelled.

b.Red Ink Test
Using a soft pen, draw a line of red ink on the inner wall of the toilet, with a depth of 25 mm; immediately flush. If no ink residue remains or if the remaining ink length meets the standards, then the toilet is deemed qualified.

Advantages of OVS Sanitary Ware

OVS Sanitary Ware is based in Chaozhou, Guangdong, with its office in Foshan, and boasts over 20 years of export experience. Our toilets are manufactured using a high-temperature firing process at 1280℃（2336℉）, ensuring high-quality ceramic bodies that excel in stain resistance and ease of cleaning. Our rigorous production controls aim to provide consumers with the finest sanitary products. By choosing OVS, you not only benefit from advanced technology but also enjoy a refined living experience.