ไอเอสโอ 5627: The International Benchmark for Paper Smoothness Testing

In the quality control system of the paper and board industry, smoothness is one of the core indicators that determine a product’s printability and surface texture. As an international standard governing the testing of this indicator, ไอเอสโอ 5627 provides a unified technical basis for paper manufacturers, printing industries, and quality inspection institutions worldwide. This article will comprehensively analyze the technical value and practical significance of ISO 5627 from the perspectives of standard positioning, core content, application scenarios, and development trends.

I. Basic Positioning of the Standard: A Professional Specification Focused on the Bekk Method
ไอเอสโอ 5627, officially titled “Paper and board — Determination of smoothness (Bekk method)”, is a specialized testing standard developed under the auspices of the Technical Committee on Paper, Board and Pulp (ISO/TC 6) of the International Organization for Standardization (ไอเอสโอ). The core positioning of this standard is to specify the technical requirements for determining paper smoothness using the “Bekk method”, providing an accurate and comparable testing approach for evaluating the performance of smooth paper and board.
In terms of its development history, the currently valid version ISO 5627:1995 is a technical revision of the first edition released in 1984. Currently, the standard is in the public comment phase for a new version, which will be updated as ISO/DIS 5627 to further optimize testing accuracy and applicability. As an internationally recognized standard, its technical requirements complement and align with major standards such as China’s GB/T 456 and America’s TAPPI T479, serving as a crucial quality determination basis in cross-border paper trade.

ครั้งที่สอง. Core Technical Content: Comprehensive Specifications from Principle to Operation
The ISO 5627:1995 version establishes a complete technical system for smoothness testing through 10 core chapters and Appendix A, covering the entire testing process to ensure the scientificity and repeatability of results.
1. Testing Principle: Defining Smoothness by Air Permeability
The core principle of the Bekk method is based on the “gap-air permeability” relationship: under a specified contact pressure, a paper sample is tightly pressed against the annular flat surface of the testing instrument to form a sealed test chamber. Smoothness is quantified by measuring the time required for a specific volume of air (typically 10mL) to pass through the gap between the sample surface and an ideal flat surface — the longer the time, the smaller the gaps on the paper surface, and thus the higher the smoothness. It is important to note that the air permeability of the sample itself can interfere with the test results, so the standard implicitly specifies requirements for the air permeability of the sample.
2. Scope of Application: Clarifying Boundaries and Limitations
This standard is not applicable to all types of paper. Its core application objects are paper and board with good smoothness, such as coated art paper and coated paper. It also clearly defines three inapplicable scenarios: first, materials with a thickness exceeding 0.5mm; ที่สอง, paper with extremely high air permeability; and third, rough paper (such as newsprint). Additionally, for extremely smooth samples, the excessively long testing time may cause operational inconvenience, so alternative methods should be selected based on actual conditions.
3. Key Technical Requirements: Details Determine Accuracy
The standard sets strict specifications for all links of the test, among which several key parameters directly affect the accuracy of the results:
•Environmental Conditions: Samples must undergo pre-treatment in an environment with a temperature of 23℃±1℃ and a relative humidity of 50%±2% to ensure stable performance.
•Instrument Requirements: The air leakage rate of the test chamber must be ≤0.5mL/min to ensure sealing performance; contact pressure, pressure gauge division value, and air flow volume must all comply with metrological standards. Appendix A specifically specifies the calibration and maintenance methods for the instrument, such as rubber pad replacement and air tightness inspection of connecting pipes.
•Operational Procedures: Clear regulations are established to ensure data reliability, ranging from the representativeness of sample collection (avoiding creases and damaged areas) to the number of tests (อย่างน้อย 5 parallel samples per group) and result calculation (taking the average after removing abnormal values).
4. Result Expression: Quantitative Indicators and Accuracy Requirements
Smoothness results are expressed in units of “seconds per 10 milliliters” (s/10mL), directly reflecting the time for air to pass through the gaps. The standard also specifies the accuracy range of the method, clarifying requirements for repeatability and reproducibility to ensure the comparability of test results across different laboratories and instruments. ตัวอย่างเช่น, high-grade coated art paper exported to the EU typically requires a smoothness of ≥1100s/10mL, while recycled paper requires ≥280s/10mL.

III. Application Scenarios: Quality Control Value Throughout the Industrial Chain
The technical value of ISO 5627 runs through the entire industrial chain of paper production, trade, and application, serving as a common technical language for all parties:
1.Production-End Quality Control: Paper manufacturers use this standard to monitor the stability of production processes, such as adjusting pulp beating degree and coating process parameters, to ensure that the smoothness of bulk products meets design requirements and reduce production losses caused by performance fluctuations.
2.Trade-End Compliance Basis: In cross-border paper trade, test results based on ISO 5627 are an important part of contractual quality clauses. Especially for products exported to the EU, they must meet both the standard requirements and the surface pollutant restrictions of the REACH Regulation to avoid trade barriers.
3.Application-End Adaptation Guarantee: Printing enterprises use smoothness testing to determine whether paper is suitable for specific printing processes — high-smoothness paper can ensure uniform ink transfer, reduce dot gain, and improve the color reproduction and detail expression of printed matter, which is particularly important for high-grade printed products such as picture albums and packaging.
4.Regulatory-End Determination Standard: Quality inspection institutions use ISO 5627 as an authoritative basis in product sampling inspections and quality dispute arbitration to ensure the fairness and persuasiveness of determination results.

IV. Development Trends and Practical Recommendations
Currently, ไอเอสโอ 5627 is in the public comment phase for a new version. In the future, it may be optimized to address issues such as testing efficiency for extremely smooth samples and adaptability to new paper materials. Relevant enterprises should continuously pay attention to the standard update dynamics. Combining standard requirements and practical experience, two application recommendations are proposed:
อันดับแรก, accurately match testing methods: Select appropriate smoothness testing standards based on paper types, avoid using ISO 5627 for rough or highly air-permeable materials, and form a complementary testing system by combining the Bekk method with the Bendtsen method, Sheffield method, ฯลฯ. ที่สอง, strengthen instrument calibration management: Conduct regular instrument maintenance in strict accordance with Appendix A requirements, focusing on air tightness and pressure stability inspections to ensure the traceability of test data.

บทสรุป
With its scientific testing principles and rigorous technical specifications, ไอเอสโอ 5627 has become an international benchmark for paper smoothness evaluation. It not only provides a unified quality language for the industrial chain but also promotes the quality upgrading of paper products through precise performance control. In the context of the global paper industry moving towards high quality and refinement, in-depth understanding and strict implementation of ISO 5627 will become an important guarantee for enterprises to enhance their core competitiveness.

Our product GA-5003 BEKK Smoothness Tester meet this standard.

เครื่องทดสอบความเรียบของ BEKK

มาตรฐาน：
ISO5627、GB456、QB/T1665

การแนะนำ:
Smoothness tester is dedicated to paper and paperboard smoothness measuring instrument, suitable for all kinds of paper and cardboard. According to the sample smoothness high three low gear, can rapid and accurate determination of various samples.

ข้อกำหนดทางเทคนิค
ช่วงการวัด:(1-9999)ส
Timer accuracy:Timer 1000s，error not exceed ±1s
Vacuum volume:Large vacuum container：（380±1）ml
Small vacuum volume:（38±1）ml
Contact pressure:（100±2）kPa
Pressure (เครื่องดูดฝุ่น) ความแม่นยำ:±0.07kPa
น้ำหนัก:About 37kg
ขนาดภายนอก:300×370×420mm
พลัง:ไฟ AC220V，50เฮิรตซ์

คุณสมบัติของสินค้า:
① With the United States imported high precision pressure sensor and no oil vacuum pump. Low noise, ความแม่นยำสูง.
② Imported electromagnetic valve and stainless steel vacuum container to ensure that equipment sealing performance, make the results more accurate and stable.
③ Liquid crystal display in Chinese, friendly man-machine interface, การทดสอบอัตโนมัติ, has the function of test data statistical processing, micro printer output.
④ Set up according to the smoothness of the high and low three gears test more rapid and accurate.

Product link:

https://www.gonoava.com/product/ga-5003-bekk-smoothness-tester/

Contact:

อีเมล: arlenliu@gonoava.com
วอทส์แอพพ์: 0086 18670728798(We chat)
If you have any questions you can send me a message or email.