Further Study: Raw Silk Electronic Test Classifica
Ms. Zhou Ying
Secretary-general of National Technical Committee 401 on Silk of Standardization Administration of China
Dear distinguished experts, ladies and gentlemen:
Today, we have entrepreneurs and experts from China, Italy, France, and other silk producing and consuming countries gathered in this beautiful city Como, and we will discuss related topics on raw silk quality and standard. We have held many meetings on such similar topics, in 2012 we have held a ISO/TC38/SC23/WG5 work group meeting on electronic test method on raw silk in Como. Today I would like to introduce our promotion and application of the international standard ISO15625:2014 silk-electronic test method for the defects and evenness of raw silk, as well as our classification work and our views.
ISO15625: 2014 silk-electronic test method for the defects and evenness of raw silk has been published for four years. In the meantime, Chinese Silk Committee, test institution, and related silk companies are working together to promote the application of the electronic test for raw silk, to study the classification standard for raw silk. Now I'd like to introduce these works.
1. Works done in the recent two years
Since the publication of the international standard on the electronic test method ISO15625:2014, under the leadership of China Silk Association, the Chinese research group on the electronic test for raw silk has been doing works on the research and promotion of the classification standard. The Chinese research group on the classification standard of the electronic test for raw silk consists of many institutes. They are Zhejiang Cathaya International Co., Ltd. (Mrs. Bian Xinger, vice secretary of International Silk Union ), National Silk Standardization Committee, Zhejiang CIQ Silk Inspection Center(Director Dong), and soochow University. Zhejiang CIQ Silk Inspection Center(Hangzhou Customs) and Guangxi CIQ Technical Center (Nanning Customs) afford the electronic test for raw silk, and they can afford inspection certificate. And they can basically meet the inspection demand for the silk exporting market.
The group keeps doing the classification research and promotion of the electronic test through all kinds of related silk meeting, and public media in the past few years.
Chinese silk companies gradually get to know the ISO15625:2014. And the number of companies required for the electronic test increases, the quantity of tested lots increases year by year. These tested silk, the Cathaya silk, Sichuan Tianhong silk, Jiangsu Huajia silk, for instance, are mainly exported to Europe, and the silk qualities are quite good, the grades are 5A and 6A. If the European companies required, the traditional test report and the electronic test report can be obtained at the same time.
From 2017 to 2018, almost thousand of electronic tests are done by the two Chinese test centers. Over 500 lots of test reports are given.
2. Study on the classification standard
In recent years we have been collecting the test data. And based on these data, we made a lot of statistical analyses, and proposed a Chinese classification draft on the electronic test with a scientific and objective attitude. We have done a lot of grading trials based on the draft.
2.1 Standard scope
This document specifies the classification criteria for raw silk according to the results of electronic test for raw silk. It is applicable to raw silk with size specifications of 18/19.8dtex (20/22 denier), whether in skein or on cone.
As the main specification of raw silk that the silk factories produce, the weaving factories use including the exported raw silk are 20/22 denier at present. And the silk samples sent to the testing institute are also mostly 20/22 denier, and few lots of other specification. Thus the large amount of electronic test data that we collected are from 20/22 D raw silk. Then when we set up the classification limits for each grade, we have to have test data of large amount of silk lots, the classification system should be established on the statistical analysis of large amount of actual test data. We cannot make the classification limits subjectively or by estimation only based on limit data, which is not scientific. Therefore we think at present we can only set up the classification system for 20/22 D based on a scientific and objective attitude. As for other specifications, we think it's premature to do this work, as we don't have enough data at present.
2.2 Specification for test length
The total test length is specified as 150000m with 12500 m for each of the 12 spindles
2.3 Grading
Currently, Chinese traditional test grades are from 6A to A grade, however the most of silk lots are 4A and above at present. And for the lots used as warp yarns and the lots exported to European market, they are mostly 5A, 6A.
Thus, we determine to set tow grades, i.e. E6, E5, only the two grades to classify these lots of raw silk with high quality.
2.4 Test items
The tests for raw silk product include quality test and weight test.
According to ISO15625:2014, we can test 13 items, they affect the raw silk quality in different extent from the weaver's aspects, thus we only choose some comparatively important items. After the traditional Chinese test, we will do the electronic test at the same time. And in our draft, we use 13 test items, and 2 labeling items. These 13 items are size deviation, maximum size deviation, total slubs by capacitive and optical sensor, thick places by capacitive and optical sensor, SIE by capacitive sensor, and CVeven%, No. of breaks during the winding test, single-end breaking tenacity and elongation and their CV% which could indicate the real tenacity of the single filament.
The two labeling indexes are cohesion and sericin content.
There are many disputes on the cohesion test method, and Japan has canceled it, but in China, we still use the cohesion test item. Although the test results are good, we still use the item, as we are finding better method to test cohesion in order to regulate the manufacturing of the silk reeling enterprises.
Sericin content also affects the silk quality in a certain extent, as at present we still don't have enough test data of this item, as there are too many Chinese silkworm spices, and too many cocoon producing areas, the sericin content varies greatly. Thus we let it be the labeling test item.
The appearance inspection of raw silk shall be in accordance with our currently used national silk standard.
2.5 Classification draft
Determination of the rating limits for each grade for the test items.
According to the customer's demands, and considering the manufacturing and management level of the Chines silk reeling enterprises, we've done large amount of electronic test data of high quality raw silk, we did a lot of data analyze, plot drawing, and held discussion among our research group almost every month when there are new test data collected, we also discuss with the reeler, the weaver, and finally we established the classification table.
2.6 Other test items
According to ISO15625, the classification and quality report of the tested raw silk should also provide the test data of other electronic test indexes including Big Slub(cap.), Small Slub(cap.), Big Slub(opt.), Small Slub(opt.), Thick Place(opt.), Thin Place(cap.), Thin Place(cap.), SIE(opt.), CV5m%, CV50m%. The test results of these indexes are provided for reference.
2.7 Test method
The test methods used in the draft mostly adopt the present Chinese test standards which are mostly the IDT ISO standard.
For example,
For size deviation and maximum size deviation test, ISO 21046.
For Defects and Evenness test, according to ISO 15625.
For the Breaking tenacity and elongation test, according to ISO2062:1993, textile-single yarn breaking tenacity and elongation test. The present Chinese standard is the muti-filament silk tenacity and elongation.
For sericin content test, according to FZ/T 40004-2009. This test method has been used for a long time, which is prove good by the users, thus we think it's time to propose a ISO standard on it.
3. Further work plan
Through this meeting we hope that will continually to enhance the communication with Italy, France and other European countries in the study of the classification standard, try to promote the application of the electronic test, as well as its classification standard, try to enhance the silk product quality, and meet the customer's demand, promote the international silk trade.
Generally we agree with the standard draft proposed by French experts. And these test items are also what we want to include in our standard. Next maybe we could work together, and improve the standard draft.
We are interested to know the data basis or theoretical basis of the Italy Classification Standard, thus we could work together and study together by considering our classification standard. Thus We hope that through this meeting, and discussion of our proposed standard, we can reach consensus on the same basis, thus we can promote the application of the classification standard of the electronic tests method.
Finally, we have got news from the ISO central secretariat that ISO21046:2018 silk- test method for determining the size of silk yarns has been published. We'd like to show our great appreciation to all the support we got from the Italy and France silk industry. With the publish of this standard, we can refer to the size test standard in our classification standard. Thank you so much!
