• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.2
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• pp.18-28
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• 2012

This study was to develop a novel automatic system for measuring St$\ddot{o}$ckigt sizing degree and contact angle at a time. The conventional methods to measure sizing degree had serious problems in obtaining significant differences according to different dosages of a sizing agent, and moreover they disclosed unique limitation due to liquid types used and tester's subjectivity. However, the newly developed system could get reproducible results through total automation of all procedures including liquid dropping, image acquisition and measurement of both St$\ddot{o}$ckigt sizing degree and contact angle. For the St$\ddot{o}$ckigt sizing test, the automatic system could measure sizing degree with more definite differences according to different dosage of AKD, compared to the conventional method. For the contact angle test, the automatic system showed a similar trend to the conventional method but had smaller contact angles due to distortion of an image focus by a sheet curl than the conventional testing machine. The problem from the image out of focus due to specimen curl will be overcome with adopting a new specimen holder for the future system.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.227-230
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• 2006

The $St{\ddot{o}}ckigt$ sizing test of the most-commonly used sizing tests is easily influenced by the individual testers' bias in recognizing red coloration. Therefore the test had to be modified to improve its reliability and reproducibility by automated recognition of a coloration procedure during testing. In order to achieve this, all measured variables occurring during the $St{\ddot{o}}ckigt$ test was first be analyzed and then reflected in the new automatic system. Secondly, the most important principle applied was to transform the RGB values of the droplet image to hue (H), saturation (S) and value (V) respectively. This is because RGB cannot be used as a color standard, owing to RGB's peculiarity of being seriously affected by the observer's point of view. Therefore, the droplet color had to be separated into three distinct factors, namely the HSV values, in order to allow linear analysis of the droplet color. When the average values of the vectors calculated during color variation from yellow to brown were plotted against time, it was possible to determine the vector value of hue, the most sensitive factor among HSV, at the specific time by differentiation of a function when it exceeds the critical point. Then, the specific time consumed up to the critical point was regarded as the $St{\ddot{o}}ckigt$ sizing degree. The conventional method took more time to recognize an ending point of coloration than the automatic method, and in addition the error ranges of the conventional sizing degrees on the specific addition points of AKD were wider than those of the automatic method.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.10a
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• pp.327-333
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• 2011

This study investigated the prime difference between different methods for measuring a sizing degree. Based on the results coming from the study, a new type of the automatic measuring system of a sizing degree. The system includes synchronized devices for measuring contact angle and St$\ddot{o}$ckigt sizing degree at the same time.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.3
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• pp.11-19
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• 2014

Reliability of the novel automatic system capable of measuring both St$\ddot{o}$ckigt sizing degree and contact angle at a time was evaluated through the calculation of its repeatability and reproducibility based on TAPPI Standard Method T 1200. As the basis weight of paper specimen increased, the repeatability and reproducibility of the automatic system became more improved than those from Hercules sizing test and contact angle test designated on TAPPI Standard Method T 530 and T 558. The more improved repeatability and reproducibility implies that a single tester can obtain the similar results under similar test conditions in spite of repetitive testing using the automatic system, and likewise that multiple testers can respectively reproduce similar data without big variation from the same paper specimen using the automatic system. In conclusion, this study is greatly meaningful in having developed the world's first automatic system to measure both St$\ddot{o}$ckigt sizing degree and contact angle simultaneously with excellent repeatability and reproducibility.