Classification of Silk Cocoons

According to the requirements of the silk-making process, the process of selecting and classifying the raw cocoons. According to the quality of the cocoon, the upper cocoon, the second cocoon (not reeling high-quality raw silk) and the lower cocoon (not reeling) can be distinguished, so as to improve the quality of the cocoons and make full use of the raw materials.

Cocoon selection is generally divided into two methods: rough selection and selection. In rough selection, only the lower cocoons are removed from the light cocoons, and the rest are the upper cocoons for silk reeling. Selecting is based on rough selection, and then selecting and removing sub-cocoons from the upper cocoons. The cocoon selection is carried out by visual inspection.

There are two types of cocoon selection equipment: plate selection and conveyor belt selection. The efficiency of plate selection is low, and conveyor belt machine selection is often used in production. It mainly means that the upper and lower cocoons are transported and bagged separately in the process of cocoon selection, and the cocoon classification is still performed manually.

Classification standards for upper cocoons

Mainly according to whether the cocoon shape is neat, the thickness of the cocoon layer is uniform, whether the cocoon color is white, and whether there are defects on the surface, it is divided into three levels:

Class 1 cocoon. The cocoon shape is neat (the cocoon width is more than 80%), the cocoon layer is thick and uniform, the color of the cocoon is basically the same, and the surface is flawless.

Class 2 cocoons. The cocoon shape is relatively neat (the neatness rate of the cocoon width is less than 70%), the cocoon layer is still thick, and the thickness is relatively uniform, the color of the cocoon is still consistent, and there are slight defects. It can be reeled into general grade raw silk.

Grade 3 cocoons. The shape of the cocoon is irregular (the cocoon width is less than 60%), the thickness of the cocoon layer is uneven, and there are more minor defects; the color of the cocoon is slightly inferior, and the secondary raw silk can be reeled without affecting the color of the silk. .

Classification standard for secondary cocoons

Double cocoon. Two or more silkworms form a cocoon at the same time. Generally, the cocoon shape is extra large and the cocoon layer is extra thick.

Yellow Spot Cocoon. The cocoon layer is polluted by silkworm urine and is caused by yellowish-brown stains. It can be divided into yellow urine, yellow urine, old yellow, hard yellow and yellow. Yellow urine means that the urine with digestive juice penetrates more than 1/2 of the cocoon layer or the area exceeds 0.5 square centimeters, and the cocoon layer is loose and soft. Relying on yellow is disease (silkworm) pupa rot pollutes the cocoon layer, and the stain penetrates more than 1/2 of the cocoon layer. Old yellow, the cocoon layer is tightened, and the total area of ​​the yellow plaque is more than 1/3 of the surface area of ​​the cocoon. Hard lumps are yellow, with yellow lumps cemented in the cocoon layer. Clip yellow, yellow penetrates more than 1/3 of the cocoon layer.

Cocoon with Prints. There are traces of grass on the surface of the cocoon. The shape of the chai print can be divided into line print, flat print and nail print. Line wood prints include a single wood print (the vertical wood print penetrates more than 1/2 of the cocoon layer, and the horizontal oblique wood print penetrates more than 1/3 of the cocoon layer) and multiple wood prints (two or more prints, of which One line penetrates more than 1/3 of the cocoon layer, or although the impression is not more than 1/3, the cocoon shape has been severely deformed.) The cocoon layer has no shrinkage and the total area exceeds 0.5 square centimeters. Nail the firewood seal, one point penetrates more than 1/3 of the cocoon layer; or although it is not more than 1/2, there are two points or more.

Rotted Cocoon. It is caused by diseased silkworms or diseased pupae that rot in the cocoon, and the polluted liquid penetrates into the cocoon layer. If the stain is printed with a serious area of ​​more than 0.5 square centimeters, it is a cocoon, if the stain is printed on both ends; printed on the waist or printed on a single head, it is clearly visible as a cocoon on the print head.