Common treatment methods for B-grade jadeite and C-grade jadeite

Jadeite optimization refers to "traditional and widely accepted improvement methods that bring out the potential beauty of jadeite and jewellery", and processing refers to "non-traditional and not yet accepted improvement methods". Jadeite optimization and processing methods can be divided into two categories. The main optimization methods are: wax dipping and heat treatment. This kind of optimized and processed jadeite is the same as untreated natural jadeite, and can be regarded as jadeite "A goods". Jadeite that has been treated with bleaching, filling, etc. is called jadeite "B goods", while jadeite that has been dyed is commonly known as jadeite "C goods".

Baking: The heat treatment of jade is mainly aimed at the red color of jade, which is also called baking treatment. Heating is to promote the oxidation of color-causing ions, turning low-value yellow, brown, and tan into bright, high-value red. Place the cleaned jade sample on an iron plate that has been prepared in advance and covered with clean fine sand, then place the iron plate on the furnace. The temperature should be 200°C. When the color of the sample turns red, stop heating and cool it slowly. After cooling, the jade will show red. The heating time is generally from tens of minutes to an hour. The raw materials for coloring are selected from yellow, brown and other colors of jadeite, which can also be cut and ground into the required jade pieces, and then cleaned with dilute acid to thoroughly remove dirt and oil stains on the surface.

Bleaching + Filling: Jadeite that has been bleached and filled is usually chosen because of its loose structure, coarse grains and is unpolished. Jadeite has a less tight structure and a base that is dirty such as yellow, gray, or brown, which seriously affects the green performance.

Acid washing and bleaching are one of the most important steps in making B-grade jade. The selected raw materials are soaked in various acids (such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, etc.). Generally, it takes three weeks to soak until the surface colors and stains are corroded away. You can also heat it slightly to speed up the bleaching process. The heating should not exceed the solution's boiling point. During the soaking process, the solution should be replaced from time to time. Apply a layer of wax on the bleached jade to fill the gaps.

Although the oxide impurities are removed from the jade raw material after acid washing, the internal texture is also significantly damaged and becomes loose, so it needs to be filled with glue to fill the cracks. The process of filling with glue is to dry the raw materials after acid washing and alkali washing, place them in a sealed container and draw a vacuum, and after reaching a certain degree of vacuum, fill enough glue in the container and immerse the glue into the jade under strong negative pressure. Before the glue is completely solidified, take the jade raw material out of the semi-solidified viscous glue, place it on tin foil and bake in the oven. The baking temperature should not be too high, as overheating will cause the resin glue to age and turn yellow. It should also not be under-baked, otherwise the glue will not solidify completely, and the hardness and strength will be insufficient, affecting subsequent cutting and grinding.

Dyeing: The dyeing process is to first bleach and clean the selected jade with dilute acid, then put it into the prepared dye (such as amino dye) or pigment (such as chromate) solution after drying, and heat it slightly. The soaking time depends on the size and texture of the jade, and usually can last from one to several weeks.

Bleaching + filling + dyeing: This treatment is often referred to as "B+C" treatment. It began to appear on the market around the mid-1990s. There are many types of dyed colors, the most common of which is green. In addition, there are red, yellow, brown and orange.

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