every tempered glass manufacturer's products must have 3C certification! Of course, in the field of tempered glass for building, the method of pasting 3C certification mark can be adopted after passing the examination (mainly for the sake of beauty), which is generally permanent! Not every piece of tempered glass must have a tempered mark. Whether there is one depends on the specific requirements of users (orderers). Tempering mark is a layer of ink printed on the glass surface before tempering, which is baked at high temperature and bonded to the glass surface to show that the glass is tempered. However, in recent years, low-temperature ink has been developed at home and abroad, that is, printing low-temperature ink on the surface of ordinary glass or tempered glass, and baking at low temperature (about 14) can also achieve the above effect. In many cases, the manufacturer failed to print the trademark according to the customer's requirements, and there were many cases of making up the printing later. From the picture, the glass should be tempered.