Moisture Permeability Test Method of Aluminum Tea Tin

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The tea may get mildewed after absorbing moisture especially in high humidity environment. In order to overcome this problem, the tea manufacturers usually use plastic composite films, aluminized plastic composite films, aluminum plastic composite films and tins in packing of the tea. All those materials mentioned above shall have sufficient moisture barrier property.

With the development of the packaging industry, a new form of packaging is emerging as the packaging of tea i.e. aluminum tea tin filled with nitrogen. This article discusses the significance and test method of the moisture barrier property of aluminum tea tin.

It can be easily understood that if the moisture barrier property of the aluminum tea tin is insufficient, the tea may get mildewed and the flavor of the tea may be lost. As a result, the taste of the tea will be compromised and its shelf life will be reduced, which may damage the image of the brand of tea manufacturer. Therefore, it is quite important for the tea manufacturers to strengthen the monitoring of moisture barrier property of the aluminum tea tin they use in packing of their tea products.

The test specimens used in the tests mentioned below are aluminum tea tin provided by one tea manufacturer. The testing instrument used to test those specimens are Labthink’s W3/230 Water Vapor Transmission Rate Test System.

Figure 1. Aluminum Tea Tin

Currently, there are mainly two categories of test methods for water vapor transmission rate i.e. gravimetric method (also known as cup method and divided into dry cup method and wet cup method) and sensor method (including electrolytic sensor method, infrared sensor method and humidity sensor method). Labthink’s W3/230 Water Vapor Transmission Rate Test System adopts infrared sensor method.

In the water vapor permeability tests with infrared sensor method, the test specimen is mounted in the diffusion cell, which is subsequently divided into a dry chamber and a controlled-humidity chamber. The dry side of the specimen is swept by a flow of dry nitrogen, and the water vapor permeating through the specimen from the controlled-humidity chamber is carried by dry nitrogen to the infrared sensor where proportion electrical signals will be generated. The water vapor transmission rate is obtained by analyzing and calculating the electrical signals. For package samples, dry nitrogen flows inside the package, and moisturized nitrogen flows outside.

The following is the detailed testing procedure for your reference.

(1)   Make holes at the bottom of the aluminum tin with special hole puncher. Apply a thin layer of Araldite rapid transparent adhesive around those holes. Fix the aluminum tin on the specific sample support.

(2)   Connect the aluminum tin with the instrument by the pipes. Then cover the sample support with aluminum tin by a sealing bag.

(3)   Set specimen name, test temperature, test humidity and other specimen parameters and test parameters.

(4)   Adjust the pressure of nitrogen. Adjust the humidity inside the test chamber to preset value. Adjust the flow rate of nitrogen until the nitrogen flow rate in the upper and lower test chambers reach standard values.

(5)   Click Test to start test. The system will automatically record the content change of water vapor in the lower humidity side and calculate the final test results.

For more details about W3/230 Water Vapor Transmission Rate Test System, please visit www.labthink.com

About Labthink Instruments Co., Ltd:

Labthink Instruments Co., Ltd is one leading supplier of packaging testing instruments, which is headquartered in Jinan, China and operated in Boston, U.S.A