Why Does the Ceramic Mug Change Color？

People often call the ceramic cup with handle mug. There is a kind of ceramic mug, its exterior is black, red, green or other color, but when pouring hot water into the cup, from bottom to top, the original color of the Cup will gradually fade, appear a special pattern. After a few minutes, the pattern became clear. If the water in the cup is cold, the design on the cup will gradually disappear, revealing the original color of the cup. What the Hell is going on here?

Why Does the Ceramic Mug Change Color?

It turns out that the color-changing mug has an extra layer of heat-sensitive material on top of the regular mug. Heat-sensitive materials, also known as thermochromic materials, its color will change from colored to colorless, or from colorless to colored, but also from one color to another color. The common thermochromic materials are composed of electron donor (chromogenic agent) , electron acceptor (chromogenic agent) and solvent. The chromogenic agent accepts the electrons supplied by the chromogenic agent to produce a color reaction, and the solvent determines the temperature at which the material changes color. The chromogenic agents include triarylmethane phenol and fluorane compounds. The chromogenic agents are mainly phenolic hydroxyl compounds and their derivatives. The solvents are mostly alcohols (such as hexadecanol) . As the temperature rises, the electron in the atom is transferred, which leads to the change of the molecular structure of the organic substance, thus the color of ceramic mugs would change. The reaction is reversible, and when the temperature is cooled, the structure of the molecule is restored to its original state, and its color is restored to its original color.

How Does a Color Changing Mug be made?

The color-changing mug is easy to make. The thermochromic material is ground into 3 ~ 10 microns powder, and made into water-based coating, which is first coated on the ordinary ceramic mug, then put into the oven and baked at about 320 °C, remove water and binder, and solidify the thermochromic material on the ceramic mug. The image or photo to be "printed" on the cup is then entered into a computer and printed on a heat transfer sheet using a special "printer" . Heat transfer printing can be printed on a variety of materials, the specific production method is to use a special transfer printing ink on transfer paper, and then affixed to the cup surface of the thermochromic coating. Place it in the oven cause heat transfer treatment is carried out at a temperature of about 220 °C. A few minutes later, a picture or photo from the transfer paper is printed on the cup, and a special color changing mug is made. When this ceramic mug is filled with hot water, the thermochromic coating becomes colorless and transparent, and the beautiful picture will be revealed.

Temperature sensing materials were first extracted from plants. In order to obtain more colors and higher yields, scientists have synthesized a large number of temperature sensing materials artificially. Different temperature-sensitive materials have different temperature-sensitive range, so the color-changing mug made of different materials varies with the temperature.