The practice of adding barium to clay bodies has also been questioned by some people, who believe that functional utensils made of barium containing clay are in danger of leaching. However, we must consider some factors that indicate the opposite:

- barium is distributed in the clay matrix, and only a very small part is added, which actually presents itself on the surface.

- barium reacts with relatively abundant flux and silicon (itself flux) in the glass clay to form insoluble silicate glass in the body.

- functional utensils completely isolate the barium on the food surface with glaze.

- recipes that use highly refined clay and minerals usually do not need barium, but many go through various chemical processes, which also has an impact on functional safety.

- after the soluble part of barium is converted into insoluble and harmless barium sulfate, the body is wetted during the preparation process.

- barium carbonate makes it possible to make bodies using native natural coarser-grained materials (which are safer in themselves because they produce less - 1 micron particles, which are fine enough to stay in the lungs).

The food and Drug Administration of the United States has no requirements for barium leaching. However, the EPA's standard for drinking water is 2 mg per liter or less. This standard is formulated to protect the most vulnerable group of people - adult males. Testing can be done at the elemental research laboratory, 309-267 West Esplanade, North Vancouver, BC. Canada v7m 1a5 604-985-0445 (they test many metals). Also at the Kirby health center laboratory, 71 North Franklin Street, Wilkes Barre, PA 18701 717-822-4278.

How serious is the foaming of soluble salt on the surface of ceramics?

like this! This clay was formed in 1957f (03 cone). This problem is common in many clay materials, but it may also occur in other materials. Barium carbonate can be used to precipitate salts in the clay matrix so that they do not float to the surface when dry.

The magic of adding a small barium carbonate to clay

Two clay mugs. The clay on the right is added with 0.35% barium carbonate (which precipitates the naturally soluble salts dissolved in the clay to prevent them from floating to the surface together with water and remaining there during drying). This process is called flowering, which is the bane of the brick industry. On the left is natural clay. The ugly appearance is the fingerprint left when this piece of debris is processed in a leather like hard state, and the salt is concentrated in these areas (another piece has also been processed, but there is almost no mark).

Low temperature clay is more likely to have this problem. If it exists, it is more likely to be ugly. The addition of barium carbonate in the salt free sample is 0.35%.

Iron clay of a typical DFAC drying tray

The middle part is covered, so it lags behind in the drying process, causing pressure and causing the disc to break. This test makes most clay crack. The severity of the crack becomes a method to compare the drying performance. Note that the test also showed that the soluble salts were concentrated in the periphery, and they migrated there from the middle part because it was not exposed to the air.