Attentions in Using Tableware Made of Tempered Glass

1. Characteristics of Tempered Glass Tableware

While the tempered glass tableware has generally well-known characteristics such as being highly strong, highly thermally resistant, thin, and lightweight, once it is received an impact and broken, there is such possibility that fragments are flown away furiously into acute fragments or narrow pieces.

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2. Accident Cases related to Tempered Glass Tableware

1. （1）In setting the tableware on tables for preparing for the school lunch, an elementary schoolchild dropped the tempered glass tableware from his hand onto a plastic tiled floor. It was broken into pieces with the glass fragments dispersed around it and hurt the appropriate schoolchild in the crystalline lens of the eyes (July 1996).
2. （2）When clearing the tables after the school lunch, an elementary schoolchild dropped the tempered glass tableware from the hand onto a plastic tiled floor. It was broken into pieces with the glass fragments dispersed around it and hurt the appropriate schoolchild in the crystalline lens of the eyes (February 1999).

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3. Attentions in Handling

As described in the aforementioned accident cases and the following reference, when the tempered glass tableware is dropped onto a hard floor (concrete floor and plastic tiled floor) and broken, the fragments may be violently dispersed to have possibility of hurting a user so that the user should take sufficient attention that the tempered glass table ware has such potential risk.

Therefore, in handling the tableware, take care of the following points.

• Don't give abrupt impact.
• If you break it, be careful that the tempered glass tableware has such characteristics as being dispersed into acute fragments or fine pieces and avoid such handling as causing damage.

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(Reference) Outline of test results in National Institute of Technology and Evaluation in the Ministry of Economy, Trade and Industry

Tests were performed on dropping strength and dispersing situation of broken fragments of the "tempered glass tableware". (The details are released on "Accident Special News No. 33 of the "Accident Information" on the Web Site http://www.jiko.nite.go.jp ) of the National Institute of Technology and Evaluation.

1. (1)Tested Products
   Same products to the aforementioned 2. (2) Accidental products (Identical products (bowl) with the accidental products) ^(note1) and comparison products (tempered glass tableware (bowl) made by a maker different from the accidental products) ^{(note 2)} were used.
2. (2)Outlines of the test results are as follows.
   
   • (a)The identical product with the accidental product and similarly used as the accidental product at school where the accident occurred was dropped from 70cm height which is the height of the elbow of a child onto a plastic tiled floor.The result shows that, when the appropriate tableware is dropped from the edge, three out of ten were broken and the finely broken fragments (needle-like fine fragments and acute thin pieces) were violently dispersed to the surrounding (dispersed in a range of the height 200cm in maximum and the radius approximately 300cm from the drop point). On the other hand, when the appropriate tableware was made to drop form the bottom, it was not broken.
   • (b)When the new ones of the identical product and the new ones of the comparison product were made to drop from the height 70cm and 110cm respectively onto the plastic tiled floor, the both of them were not broken in the both cases respectively.(When dropped onto a concrete floor, some of them were broken.)
   • (c)When the tested products (a) with fine damage formed therein were made to drop from the height 70cm and 110cm onto the plastic tiled floor for breaking respectively, finely broken fragments (needle-like fine fragments and acute thin pieces) were violently dispersed to the surroundings in the both cases.The respective dispersion states are as follows.
     1. i）The new identical products with fine damage formed therein
        These were dispersed in the range of approximately 120cm - 200cm in the height and approximately 250cm - 300cm in the radius from the drop point.
     2. ii）The new comparison product with fine damage formed therein
        These were dispersed to a range of approximately 65cm - 115cm in the height and approximately 170 - 280cm in the radius from the drop point.

(Note 1)

Tempered (laminated and tempered) product formed by a method for enhancing fracture strength by sticking two types of glasses having different thermal expansion coefficients in a molten state, cooling it, and forming a compressive stress layer on the surface layer.

(Note 2)

Tempered (forced-air-cooled tempered) formed by a method for enhancing the fracture strength by heating the glass to a high temperature near the softening point, suddenly cooling it, and forming s compressive stress layer on the surface layer.