Crazing is the effect on pottery which causes it to have a web of tiny cracks over its surface. These are not cracks in the actual structure of the pottery but actually an effect on the glazed part of the pottery.
Avoid eating directly off of plates with crazing. Crazed plates are fine for occasional use, preferably with a barrier between the food item and the dish. Crazed pieces are great for upcycling into decor with non food-related uses, like a jewelry organizer or accessory tray.
Conversely, ways to correct crazing include changing to a different clay body which better fits the glaze, adding silica to the existing clay body or increasing the firing temperature. Commercial clay bodies often already have silica added to prevent crazing.
Crazing is caused by the glaze being under too much tension. This tension occurs when the glaze contracts more than the body during cooling. Because glazes are a very thin coating, most will pull apart ar craze under very little tension. Crazing can make foodsafe glazes unsafe and ruin the look of a piece.
Generally, crazing is considered a glaze defect because the vessel can be significantly weaker than an uncrazed pot. Craze lines can also harbor bacteria or germs. Therefore, dinnerware pottery should be uncrazed ware.
Crazing Is Caused by Tension during Thermal Expansion
It's very common, and it can occur in any glazed Pottery piece at any point in its lifetime.
Cracking is easily identified by the observer visually and through physical touch. It's also easy to understand that the material has been weakened when cracks are present. Crazing: internal fracturing without a change of the surface texture.
In some cases, crazing is desirable and can actually increase the value of a piece, particularly in certain types of pottery such as majolica or Raku. However, in most cases, crazing is considered a flaw and can significantly decrease the value of a ceramic piece, particularly if the crazing is severe or extensive.
Crazing diminishes the value of most pieces depending on the severity and rarity of pieces. Royal Winton is a manufacturer known by collectors to have a propensity to craze.
Crazing is a glaze defect of glazed pottery. Characterised as a spider web pattern of cracks penetrating the glaze, it is caused by tensile stresses greater than the glaze is able to withstand.
Crazing is something that happens naturally in ceramics and in no way affects the durability of the tile. Over time, your tile may develop a bit of crackle that wasn't there when it was installed initially. Don't fret! This is perfectly normal and your tile is A-ok (more on crazing over time here).
Porcelain tile has a 60+ year life expectancy, so you definitely get your money's worth. It's perfect for walls, floors and indoor/outdoor installations. Rated for high-traffic areas, you won't have to worry about your porcelain floor degrading over time.
One of the most common causes of hairline cracks on porcelain sinks is thermal stress. Considering porcelain is usually layered on metal (which conducts heat), the sink loses heat rapidly and can become very cold—even when the room isn't cold.
If the piece is old enough, the glaze may contain lead, which can leach due to the crazing. In that case, the piece should definitely be discarded. Technically, most health codes require crazed dishware to be discarded, although you can assess your tolerance for risk.
Despite porcelain's fine make, high price, and expensive quality, eating food off a porcelain dinner set may also invite toxins into your body. The brightly colored, intricate designs on china sets are usually from a finish that uses cadmium or lead to achieve such colors.
Mix oxygen bleach powder in hot water, allow it to cool to room temperature, and allow your dishes to soak. This will remove most stains, even the crack-like "crazing lines" which may begin appearing as ceramics age.
To fix it, a significant change is needed, one that not only addresses fixing the crazing phenomenon but that restores the fired strength of the clay/glaze 'marriage'. The bottom line is that crazing is best solved on the oxide level for the glaze and the material level for the body.
Crazing generally occurs with age but there are other factors which cause immediate crazing which include: Temperature and humidity changes which causes the glaze to crack. It can be caused by moisture getting into the glaze and forcing cracks in the glaze.
Many old china dishes and mixing bowls can contain lead, especially if they are bright colors and very decorative. The concern is the lead can leach from the dishes and is highly toxic to humans and pets. If the dishes are cracked, chipped or the glaze is wearing off, they should not be used to prepare or serve food.
Today, porcelain is a common product but the good quality collectible items from the famous manufactories or made by artists are still quite expensive. The most valuable are in the antique porcelain pieces from the 18th and 19th centuries, made for royal courts.
Your grandmother's antique china or her old mixing bowls can contain lead. Leaching lead from antique china may be toxic. This is the case with many pieces of antique and vintage china. Many of the old glazes used on antique or vintage china contain some level of lead.
When asking “what is my antique worth?” you need to start by looking for chips in the piece. If the base or rim has small chips in them, it won't be worth as much. Often, it can be hard to see small chips on the rim, so always run a finger around the area. If you feel any sharp edges, the piece is chipped.
Craze lines are a normal and common occurrence. They don't mean that your teeth are weak or prone to cracks. They usually don't worsen or lead to cracks. They may, however, make teeth more prone to cavities, though rarely on the front teeth.
Crazing is caused by drying out of the concrete surface, particularly when the surface has been exposed to low humidity, high air or concrete temperature or hot sun during placement for the concrete mix. The cracks are typically shaped like irregular hexagon patterns not more than 50 to 100 mm across.
Crazing is caused by drying out of the concrete surface, so it is particularly common when the surface has been exposed during placement to low humidity, high air or concrete temperature, hot sun, or any combination of these.