How is B-grade jadeite made? How to identify B-grade jadeite?

The process of producing B-grade jadeite

1. Material selection

The jade raw materials suitable for B-grade processing are jade varieties that contain secondary colors, have loose structures, coarse grains, and relatively inferior texture, such as jade varieties with obvious yellow-brown, black-gray secondary colors, and seriously affect the green performance. Jade varieties with dense texture, black ringworm, or good transparency and no obvious dirty colors are generally not used for B-grade processing. There are two reasons for this. First, this type of jade is not easily bleached by acid or alkali, and black ringworm is a hornblende mineral that is not easily dissolved by acid and alkali. Second, jade with good texture and good color is more valuable without treatment than after treatment.

2. Cutting

In order to make the pickling and filling more complete and faster, the large pieces of raw materials should be cut into jade pieces or jade rings of a certain thickness according to the needs.

3. Acid washing and bleaching

Soak the selected raw materials in various acids (such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, etc.), generally for 2 to 3 weeks. You can also heat it slightly to speed up the pickling process. The heating should not exceed the boiling point of the solution. The solution should be changed from time to time during the soaking process. The purpose of pickling is to remove the yellow-brown and gray-black colors.

4. Alkaline cleaning to increase clearance

After acid washing, the jade raw material has been cleaned and dried, and then soaked in an alkaline aqueous solution (caustic soda NaOH solution). The corrosive effect of alkaline water on silicates can increase the porosity. Another purpose of alkaline washing is to neutralize the acidity caused by acid washing. Generally, the B goods after alkaline washing are called big B goods.

5. Filling

After acid washing and alkali washing, the cracks and pores of jadeite increase, the density decreases, the ability to resist mechanical force decreases, and the transparency becomes worse. It must be consolidated with resin glue to increase strength and transparency. The method is to dry the raw materials after acid washing and alkali washing, place them in a sealed container and evacuate them. After reaching a certain vacuum degree, fill enough glue in the container to make the weak jadeite raw materials completely immersed in the glue, and then increase the pressure so that the glue can fill all the gaps.

6. Consolidation
Before the glue has 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. Do not bake insufficiently, otherwise the glue will not solidify completely, the hardness and brittleness will be insufficient, and the subsequent cutting and grinding will be affected.

Identification characteristics of B-grade jadeite

1. There will be acid-etched reticulation or glue-filled pits on the surface. Because the hardness of the resin filled in them is low, concave grooves will be formed during cutting and polishing. They are distributed along the boundaries of the particles and look like reticulated cracks on dry soil. If the acid pickling is too strong or the bonding treatment is not ideal, a large number of sand holes will appear on the polished surface.

2. The knocking sound of some B-grade jadeite is dull and hoarse, not crisp enough, and different from the natural one.

3. Acid-etched and filled cracks usually have an oily luster. The open cracks are very clear on the surface, but the parts extending to the inside are not obvious and will not block the passage of light. The healed cracks of natural jade are very clear inside.

4. Observe the internal structure of the jadeite. The boundaries between the acid-washed grains are blurred, especially for the coarse-grained B-grade jadeite.

5. The base color is clean and free of impurities. After acid washing and bleaching, the impurities are dissolved, the yellow base and dirty base are removed, and the white part is carefully observed, there are no impurities and gray-yellow components.

6. The density of jadeite will be significantly reduced after acid washing and filling, especially the jadeite treated with the so-called "Big B" treatment (the relative density of natural jadeite is 3.33), which can be checked through the appraisal certificate

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