1. Bubbles
1.1 Glass skin bubbles are not allowed to exist;
1.2 Thin-skinned air bubbles ruptured by squeezing with nails or pins are not allowed to exist;
1.3 For small air bubbles with a diameter of <0.8mm, no more than 3 in the range of 20mm*20mm, and the spacing is greater than 50mm, no more than 5 on each product, and seal the sample if necessary.
2. Calculus
2.1 Unmelted or refractory opaque inclusions in glass;
2.2 Stones protruding from the surface and sharply scratching nails are not allowed;
2.3 Stones with cracks around them are not allowed to exist.
3. Cracks
3.1A crack that extends through the thickness of the glass. Under the inspection light, the bright spot of the crack can be seen visually. It is not allowed to exist.
4.Four, scratch
4.1Scratch hard with a sharp object, forming a linear abrasion on the glass surface. Luminous scratches can be visually observed under the inspection light, and are not allowed to exist.