Ceramic Mug Group, in the process of making ceramic mugs,
raw materials made of
clay after molding,
drying ceramic mugs, billeting and other processes, before the billet glaze. Some of the raw ceramic mugs need “plain firing” process, the rest is directly glazed. So, what is the plain firing in the end? What kind of situation needs to burn process? In fact, vegetarian firing is a kind of early firing, it has an important role in improving the quality of ceramic mugs, of course, this process will also increase the ceramic cup in the production of links in the cost and time.
1. What is vegetarian firing?
Vegetarian firing is a ceramic mug billet in the dry, repair billet, before the formal glaze firing, a low-temperature firing (usually 700-900 ℃), the mud “half-burned”. Burned blanks as crisp and hard as a cookie, but not yet turned into porcelain.
2. What needs to be fired?
2.1. 4 kinds of situations that need to be fired:
2.1.1. to do complex decoration: such as hand-painted patterns, underglaze color, underglaze appliqué (plain firing after the billet water absorption, underglaze color is easy to color without losing color).
2.1.2. the billet is too thin or complex shape: such as thin tire mug,
shaped mug (high strength after plain firing, not easy to break when handling and glazing).
2.1.3. with special glaze: such as
matte glaze (matte glaze liquidity is poor, direct glaze on the blank is easy due to uneven absorption of water on the blank resulting in mottled glaze. Plain firing after billet water absorption stabilization, glaze distribution is more uniform.) The crystallized glaze (crystallized glaze firing temperature is high 1320 ℃, and need to keep warm for a long time. After firing, the body is strong enough to withstand the thermal stress of glaze firing, avoiding cracking.) .
2.1.4. Export or high-end products: Plain firing can expose the defects (such as dark cracks) of the blank body in advance and reduce the final firing scrap rate.
2.2. There are 3 kinds of cases that do not need to be burnt:
2.2.1. Ordinary mugs with large quantity and low price: direct raw glaze, saving time and money.
2.2.2. high strength clay: such as the addition of clinker (crushed porcelain powder) of coarse pottery mug, itself is not fragile. 3.
2.2.3. glaze is simple: such as monochrome glaze, direct spray glaze can also be attached.
3. The advantages and disadvantages of plain firing
3.1. The advantages of raw blanks after plain firing are:
3.1.1. the billet becomes hard, the handling is not fragile.
3.1.2. more uniform glaze, bright color.
c. early detection of cracking, deformation defects.
3.2. Disadvantages are:
3.2.1. firing more than once, time-consuming and gas-consuming.
3.2.2. vegetarian firing occupies kiln space, lower output.
3.2.3. Improper operation may overfire (glaze can't stick after porcelainizing the blank).
4. Vegetarian firing operation steps
4.1. Load the kiln
- How to set up: mugs face down, at least 2 finger width apart (to prevent sticking).
- Pad what: the bottom of the mug sprinkled with a layer of alumina powder or pad refractory sand (to prevent sticking to the kiln board).
4.2. Firing temperature
- Ordinary clay: Fired to 800-850 ℃ (the body becomes light red, knocking sound like tile).
- High-white porcelain clay: fired to 900-950 ℃ (the body of the white, knocking sound like tiles).
4.3. How long to burn?
- Warming up: from room temperature to the target temperature in about 5-6 hours (150℃ per hour).
- Holding time: 30 minutes after reaching the temperature (to let the heat penetrate into the center of the billet). Cooling: Turn off the kiln to cool down naturally.
- Cooling: Turn off the kiln and let it cool down naturally to below 100℃ before opening the door (rapid cooling will cause cracks!). Cooling: Turn off the kiln and let it cool down naturally to below 100℃ before opening the door (rapid cooling will crack!)
5. Precautions
5.1. Inaccurate temperature will turn over:
- Must use thermocouples to measure the temperature, can not rely on experience to see the color of the flame!
- Temperature is too low (<700 ℃): billet strength is not enough, a touch will be broken.
- Temperature is too high (> 950 ℃): body porcelain, glaze can not hang. 2.
5.2. Check after firing:
- Drip test: drop a drop of water at the bottom of the mug, within 5 seconds to seep in is considered qualified (water absorption rate of 12% -15%).
- Failed products: cracked sound muffled, no water seepage directly scrapped. 3.
5.3. Storage of plain billet:
- Put in a dry box (humidity <40%), otherwise the glaze will blister after absorbing moisture.
In summary, plain firing is a ceramic mug in the production process to improve the quality of the process. It can improve the quality of the raw ceramic mugs, in the later glazing, hand-painting, paste underglaze flower paper and other processes, is essential. Simply put, high-end ceramic mugs often need this plain firing process. The ceramic mugs made in this way are more environmentally friendly and exquisite. Of course, the vegetal firing process will increase the cost and time of production, which means that when
customizing ceramic mugs, the price of such ceramic mugs is also higher. This kind of ceramic mugs after the plain firing process is more suitable for coffee shops, branded gifts and so on, which have higher requirements for quality.
