2 Key technique factors determining the quality of ceramic tableware

1 Quality standard quality of ceramic tableware

Since the reform and opening-up policy, China’s ceramic products have become the first large-scale export commodities. With the continuous increase of the output and export of China’s daily-used ceramics, China has become a well-deserved large-scale production and trade of daily-used ceramics. The quality of ceramic tableware products has become a serious topic.

Many countries in the world have put forward more strict quality and safety requirements for daily ceramic tableware products in China. There are many factors that could result in the hazard if anything goes wrong during the production process. So what are the main quality standard in determining the quality of ceramic tableware?

The main technical indicators for evaluating daily ceramic tableware include the following aspects, appearance quality, and safety indicators.

2 Appearance quality

Appearance quality is an important standard for the classification of the quality of ceramic tableware. The inspection of appearance quality includes the error of capacity, caliber, height, weight, and defect. Different regions and areas have different methods and requirements for appearance quality ranking.

The diameter, height, weight of the same batch of tableware products should be the same. The samples should within the error range, and the deviation should be more. How many visible and non-visible defects of different types, these are the indicators to be measured when determining the appearance quality of ceramic tableware and different standard have different tolerance to these above factors.

The excellent products can be equal to the international advanced level, first-class products for the domestic advanced level, qualified products for the domestic general level. The appearance quality of high-quality goods requires high, small deformation. Comparing to the excellent class, the first-class and qualified tableware products allow the existence of defects in a more relaxed way.

Specific reference can be made to the specifications of different household ceramic products, such as ‘National Standards of the People’s Republic of China- Bone China.’‘National Standards of the People’s Republic of China- porcelain.’

3 Safety indicators

The safety indexes in the quality of ceramic tableware mainly include lead and cadmium release, thermal stability, dishwasher stability, microwave oven stability, radioactive material content, and potential pollution to the environment.

3.1 Lead and cadmium release.

Lead and cadmium release is not only an important safety and health index of daily ceramic tableware products, but also a very concerning issue, the amount of lead and cadmium directly affects the health of users.

The presence of lead and cadmium is due to the raw material, the firing environment, surface decoration patterns, the presence of lead due to the composition of the ceramic pigments in the patterns, and possibly the addition of lead due to the low firing temperature of the surface glazes of the products, improper control of the production process can easily lead to excessive release of lead and cadmium in the process of use.

The frequent use of such products is liable to lead and cadmium Heavy Metal Poisoning. you can refer to the article “Factors That Affect Daily-use Ceramic Decal’s Lead and Cadmium Dissolution”

Given the capacity limit of these chemicals, the country has strict mandatory standards and requests, its scope of application has covered all daily use ceramics tableware.

Different sizes, shapes, requirements, and standards impose different limits on lead and chromium content to the determination of the quality of ceramic tableware

3.2 Thermal stability

Thermal stability is referring to the exchange of the product in the heat and cold suddenly without cracks or damage. The quality of thermal stability can reflect the service life of ceramic tableware products. The larger gap in the temperature of heat and cold exchange, the longer the service life of the ceramic tableware products.

The standard testing method generally refers to putting the products in the hot water of 180 degrees, and taking out and then putting in 20 degrees water and taking out, observing whether there is any damage, if the products can pass this test, its service life can reach above 2 ~ 3 years commonly.

3.3 Safety testing of microwave ovens

Due to the extensive use of microwave ovens and dishwashers, foreign-invested importers must put forward washing resistance and microwave oven safety “requirements for daily ceramic tableware in China, testing methods of washing resistance and microwave oven safety mainly includes “test method for mechanical dish-washing resistance of domestic ceramic ware”

The test method of microwave-safe measures whether the electric arc is produced in the microwave heating process and if damage occurs and the maximum surface temperature of the daily ceramic product after microwave heating under the condition of moisture.

Products suitable for a microwave oven can not use metal surface decoration, such as gold line decoration or a pattern that includes gold pigment. the thermal stability of a variety of products has a corresponding testing method.

For case study, pls refer to is bone china microwave safe?

Bone china tableware that is microwave safe (no gold pigment)

3.4 Safety testing of dishwashers

The current standard for dishwashers is the “test method for the resistance to microwave heating of mechanical domestic ceramic ware”.

In this test, The unused sample is placed in a static solution of a specific alkaline detergent at 75±1 degrees for 16 hours, and then the sample is visually examined and compared with similar untested samples to determine the color and glossiness, to see if there is any change due to the detergent.

Personally, I don’t recommend clients choosing this kind of design if the use occasion includes dishwasher, as the gold could wear away after many times using.

3.5 Products environmental technical requirements

the standards stipulate that the pollutant discharge of the product production enterprises must meet the requirements of the national or regional pollutant discharge standards. In the actual production and operation, the regulations also affect the normal operation of producing factory, thus affecting the timely delivery of products.

4 Other tests

Other tests that concern the quality of ceramic tableware include Radioactive material, water absorption, deformation, glaze hardness, transmittance, whiteness, dimensional defects, permeability, gloss, permeability, and so on.

According to the application scenario requirements, and then following local regulations and policies, the test is conducted by the relevant professional testing institutions.

Common international testing standards for quality of ceramic tableware

Lead contamination of imported and domestic ceramics by FDA/ORA CPG 7117.07-1995

Cadmium contamination of imported and domestic ceramics by FDA/ORA CPG 7117.06-1995

California Prop. 65(California Prop. 65-2002)

Israel SI 1003-1999 metal dissolution and marking of ceramic ware

Permissible limits of lead and cadmium release:

International Standard ISO6486/2[1999(E)] permissible limits of lead and cadmium release from ceramic products in contact with food

European Union Directive 84/500/EEC permissible limits of lead and cadmium release from ceramic products in contact with food.

German DIN 51032 limit values for dissolution of health hazards in household utensils

Sri Lanka’s import regulations DOPL No. 326(29 February 2000)

Lead and cadmium in Sri Lanka’s ceramics are permitted to be dissolved to the limits specified in the International Standard ISO6486/2[1999(E)].

12) Oct P 50186-92 national standard of the Russian Federation “Permissible limits of lead and cadmium release from ceramic utensils in contact with foodstuffs”

5 Test demonstrations

The quality of ceramic tableware has always been a big concern for all people. Different market requirements have different requirements, in our daily work, we cooperate with customers’ requirements to apply different tests. Here’s a report on lead and cadmium.

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