The main causes of cracking of the ceramic mug edge include the following.
- The drying speed is too fast.
- The mouth of the vessel is too thin to withstand external forces.
- If a ceramic vessel has just been prepared and cracks have begun after undergoing any important drying stages, it is likely that the mud is used too many times. It is also possible that the additional filler (clinker or sand) in the mud is excessive. In some cases, the recycled or re-distributed mud will become too many to be used, such as The mud that has been repeatedly drawn on the blanker.
The widest part of the ceramic crack is located on the edge of the vessel, which means that the part is the starting point of the crack. In the case of this type of cracking, it is caused by uneven drying.
- Glazing the ceramic body, when encountering the joints with excessive thickness and thickness, it is easy to cause the thin parts (usually the mouth of the book) to be too wet, and these parts will be in the drying process later. Under the influence of external forces.
- When the dried body is placed in a humid environment, the phenomenon of water absorption again occurs. This phenomenon is quite special. I have seen an example of a semi-dry body that absorbs water again and is crushed by its own weight when the body softens to a certain extent. When a dry blank is placed in a humid environment, the green body will expand while absorbing moisture again, which will cause a tensile force in a portion where the thickness difference is large during a later drying process. Ceramic blanks with relatively low clay content, such as some low-temperature white clay and porcelain clay, cannot withstand the tensile force generated during re-absorption due to their low green strength, and many small cracks appear, and these small cracks are only It can only be seen after the burnt.
- One of the most common reasons is improper repair. The blanking tool must be very sharp and must be cut or scraped until the blank is half dry. When the blank is too dry, its strength is very weak, and in this case, the blank is easily pulled by the blanking tool. As mentioned earlier, the small cracks on the outer surface of the blank multiply the pressure. In general, it is possible to effectively prevent cracking by wiping the outer surface of the blank with a wet sponge after the completion of the blanking.
- In the field of ceramic industrialization, the cracking of the plate mouth is called “break edge”, which is caused by an improper dressing. Place the plate blank in a dry or nearly dry state on the electric turntable and trim the edge of the plate at an appropriate angle with an “L” shaped blank. If the angle of contact between the blanking blade and the blank is not appropriate, the blade will quickly jump and collide or pull the outer surface of the vessel, and the resulting cracked sleeve will appear after firing.