5 Methods for identifying ceramics suitable for microwave ovens and dishwashers

Identification of materials and craftsmanship

• Prefer underglaze/in-glaze colors

Underglaze and in-glaze colors are isolated because the pigments do not easily release cadmium at high temperatures. It is qualified if the pattern is scratched with a bracket without any bumps and the color penetrates the glaze. How to distinguish between hand-painted ceramics and decals 

• Bone china

High-quality bone china (containing more than 30% bone powder) can be microwaved if the glaze is intact and marked “Microwave safe”, but sudden cooling and heating should be avoided at the same time. Poor-quality bone china tableware will crack easily when heated in a microwave due to its high porosity.

• Knock and listen to the sound

Tap the wall of the cup with chopsticks, and the sound is crisp and metallic, indicating that the body is dense and suitable for microwave ovens.

Observation through light: observe the ceramics under the light source. High-quality ceramics are uniform and free of black spots, while impurities or bubbles can be seen on low-quality ceramics (high-temperature washing in dishwashers will accelerate deterioration)

Labeling

•  Microwave safe: Is there a symbol (three wavy lines) or “Microwave safe” marked on the bottom of the ceramics
• Dishwasher safe: Is there a symbol (water droplets in a square + fork and spoon) or a “Dishwasher Safe” label
• Product certification: For example, FDA or LFGB certification

Products that do not meet the requirements

• Handmade ceramics: non-industrially produced wood-fired pottery, stoneware, etc.
•  Melamine resin: It looks similar to ceramics but becomes melamine formaldehyde resin. It releases toxins above 60°C and must not be placed in a microwave oven.

Microwave Self-Test

Fill the ceramic cup with cold water, put it in the microwave and heat it for one minute, then take it out and touch the cup body

• The water is hot, and the cup is slightly warm: qualified
• The cup body is hot: the body absorbs heat strongly, and it is forbidden to use the microwave

Use and Maintenance

• Putting porcelain in the microwave without anything inside will cause local overheating and cracking
• Long-term microwave lemon juice, vinegar, etc., may corrode the glaze and cause lead and cadmium.
• The upper temperature of the dishwasher is lower, which can reduce the damage of the high temperature of the dishwasher to the porcelain glaze.

Summary:

1. Check whether the certification marks are complete
2. Whether the knocking sound is crisp
3. Microwave to test the heat absorption of the cup body
4. Stay away from metal decorations and overglaze colors

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