Today's opening is to send a wallpaper picture that I like super much this year.,(There are a few more in the phone that are also big love.,If you like it, you can find me); 2024 is the Year of the Dragon, which is the traditional Chinese destiny of the Nine Purple Departures from the Fire, which is considered to be very auspicious and wealthy during this period, with the saying of "once in a century"; Nine luck corresponds to the I Ching gossip in the hexagram, the five elements belong to the fire, do the cause of related industries this year will usher in good luck, in this way, the sincere blessing of Xiaochuan's heart to all ceramic peers, I wish you who see the article "like a dragon flying in the sky, the cause is thriving";
In today's article, we will take advantage of this year's good luck omen to talk about the "art" of fire;
When it comes to the number of firings in the porcelain-making process, you may be confused. Today, we're going to reveal the difference between primary and secondary firing and tell you why some products are better suited to which process.
The primary firing and the second firing make the ceramic products rejuvenate and benefit from economic benefits
In the production process of ceramic products, firing is a crucial link. In the firing process, there is often a choice between primary firing and secondary firing. These two different firing methods have their own advantages and application scenarios for different products and needs.
Economical and practical one-time firing
First of all, primary firing is more economical than secondary firing because it consumes less energy. In addition, there are other firing cost factors that need to be considered. Therefore, from the point of view of cost control, one-time firing is more attractive.
One-time firing is particularly suitable for large-scale products with complex shapes and high value, such as sanitary ware. Because these products cannot obtain too much dense volume in the kiln, it is not economical to use secondary firing, which consumes more energy and requires a space to store intermediate plain firing blanks. In addition, these large products do not require overall glazing and are supported by their own weight without deformation during a single firing.
For tableware and other products, the method of double firing is often used. This is due to the large loading capacity of plain kilns, especially for porous blanks (e.g. fine pottery plates, face tiles) and glaze kilns. In addition, it is more economical to store low-value blanks because of the high loading density of the various shapes. This intermediate storage process increases the flexibility of production, especially when manufacturing a variety of shapes, and it is possible to directly use the semi-finished products from the plain firing stock to meet the order demand, without having to start from the blank mud. The main advantage of secondary firing is that it can be used to select plain sintered blanks and reject defective semi-finished products, thus reducing costs comparatively.
Technical viewpoints and advantages of secondary firing
From a technical point of view, in some cases, secondary firing is necessary. For example, for a single product, such as a shallow flat product of ashes china, support is required to prevent deformation when plain firing. In addition, the glazing of plain fired products is easier to control than that of green billets, which is conducive to improving quality and reducing losses.
The advantages gained by secondary firing can outweigh the increased firing costs. However, this situation is not fixed, and it is expected that the application of the primary firing process will increase in the future.
In a single firing process, the glaze and the body mature at the same time. Therefore, vitrified glazes cannot be completely closed before the reaction of the green bodies stops and the gases are discharged, unless these gases can be discharged from an unglazed open porous blank, e.g. porous bricks are glazed on one side only. Complete closure before the glaze matures can result in substandard porous areas on the surface. When the green body and glaze are heated together, the formation of an intermediate layer often increases the strength of the product. This phenomenon is especially noticeable when the green body is completely vitrified.
For secondary firing products, the glaze firing temperature is usually lower than the plain firing temperature, so that no further shrinkage of the green body occurs. This applies to vitrified porcelain and fine pottery products that are fired twice and can be fired using tripod supports, and where a relatively high kiln loading density can be achieved in the glaze kiln. Feldspar porcelain, on the other hand, is fired at a low temperature (900-1000°C), resulting in a hard, porous blank.
After glazing, the product is fired to a very high temperature (approx. 1400°C), which allows for vitrification of the green body and maturation of the glaze. For shallow flat ceramic products, it is common practice to use a single cushion cake for glaze firing. Fine pottery can also be produced using low-temperature plain firing and high-temperature glaze firing processes.
Towards the future of primary firing
With the increase in the profitability of fast-fired face bricks, there is a growing awareness that there are many benefits to be gained from using the one-time firing process. Facing bricks have a straight shape and only need to be glazed on one side, making them particularly suitable for rapid one-shot production processes.
In the primary firing process, the glaze usually contains a binder, which controls both the rate at which water evaporates from the glaze slurry and the movement of water into the porous blank. In addition, the binder increases the hardness of the dry glaze surface, which is conducive to the handling operation of the green body before entering the kiln.
Through the comparative analysis of the two methods of primary firing and secondary firing, we can see their applicability and advantages and disadvantages in different situations. This contributes to the development of the pottery process and the improvement of product quality, while also providing more options for the industry. In the future, with the advancement and innovation of technology, we are expected to realize the application of the primary firing process in more fields.
ps: Attach my favorite mobile phone wallpaper, if you like it, you can ask for the original picture
Today's product recommendation: big red glaze frit.
The big red glaze frit of high-temperature reduction oxidation firing can be mailed free of charge for samples