Polishing
| Once a plate has been brought into shape and has reached the stage where it can be further processed by firing or drying, whether on a single-place roller or on a street, its bases (set rings) are rough and sharp-edged. They must be reworked to prevent the porcelain from scratching itself when stacked, because the bottom of a base can damage the glaze on the top. This work is characterized by high intensity and, due to the strong dust formation, certainly not harmless to health. Of course, this does not only affect plates, but all porcelain articles with unglazed areas must be reworked. | |
| Why you have unglazed areas? Well, the porcelain must be free standing during firing, i.e. the contact points of the base to the furnace capsule (or carrier plate) cannot be glazed, because the article is standing on it. So you can see that there can be no 100% through glazed porcelain article: Somewhere you will always find the rough spots of the glow firing. From France comes the firing method of the "hanging firing". There, the plate is not placed on a device, but is hung in special fireclay racks. This firing method guarantees glazed setting rings, but the "fingers" of the frame leave unsightly, partially sharp-edged contact points on the back of the article in the opposite ratio of 1 : 2, a total of 3 focal points. |
| The polishing robot Similar to the one-armed bandit (the horizontal robot is often called that) there are hardly any limits to mechanization. For example, there are factories that now use polishing robots instead of polishing lines or hand polishing to grind floors and rough areas smooth. Although impressive to look at and characterized by unattainable precision, we consider the use of these machines to be questionable in view of the high acquisition and set-up costs. We think that a company should also provide jobs for not top qualified employees and the purchase of "job killing machines" should not be subsidized by the state or taxpayers through depreciation and special subsidies. |
The polishing tunnel
A grinding machine, which is called "the grinding tunnel" in German, is much more complex and even more precise. The porcelain parts are placed on treadmills and ground under strong rotation and water sprinkling. On the one hand, this has the advantage of low dust generation, which saves dust filter systems, and on the other hand, the diamond grinders wear out less. Furthermore, the machine can be adjusted quickly, which makes it also useful for the realization of smaller runs.