Tableware troubleshooting

Are any of these issues troubling your tableware? 

Body preparation – are you left with sieve residue? After milling or blunging, measuring the quantity and type of residue found on your sieves is a key step in the ceramic process. If observing residue with a magnetic bar and optical microscope shows the presence of magnetic, coloured or unusual particles, there may be a risk of defects later on in the process. Let our experts help you test and measure your sieve residue and solve these issues before they occur. 

During casting, when the slurry is in contact with the mold, segregation of particles may occur creating defects such as casting spots and casting cords after firing. This segregation is caused by the orientation of particles during the filling of the mold. Adjusting the rheological setup of the slurry is the best way to control and prevent these defects. Increasing the density of the suspension or the thixotropy will reduce this problem. The use of kaolin such as our Grolleg grade or our ball clays improves density and controls thixotropy.

Kaolin

• UK: Standard Porcelain

Ball clay

• UK: Hywite Superb
• France: FMT

Do you lose products due to cracks forming while drying? The root causes of drying cracks are multiple and often stem from the shaping stage, too fast drying, uneven atmosphere (temperature or moisture) or careless storage.

From a raw materials point of view, the use of minerals promotes good particle packing able to absorb or prevent the generation of cracks leading to a significant improvement in yield. Strength can be increased by the use of finer and stronger kaolins such as Grolleg, Standard Porcelain or Super Standard Porcelain.

Kaolin

• UK: Grolleg, Standard Porcelain, KaoPearl CNL30
• New Zealand: Premium

Ball clay

• France: FMT

Glaze powdering can occur during application. After glazing, the surface of the glaze can be powdery or the glaze layer detaches during handling. If the adherence of the glaze to the body or substrate is not good enough, this can generate defects. The use of fine kaolin with high binding behaviour is the best solution. Talk to our teams about which kaolin is perfect for you. 

If your ceramics are deforming or developing black spots during firing certain kaolins, such as our Premium grade, have a mineralogy and particle size distribution which contribute to reducing the risk of deformation, while we can process kaolin specifically to avoid black spots. 

Kaolin

• New Zealand: Premium

Highly processed products

• France: BIP
• UK: Grolleg, Standard Porcelain, KaoPearl CNL30
• UA: KaoShine BB30
• New Zealand: Premium

Whatever issues are blighting your porcelain, talk to our expert teams to see whether there’s a mineral that could help.