The “ TAPPI T 563 Equivalent Black Area (EBA) and Visible Dirt Count in Pulp, Paper and Cardboard by Image Analysis” standard, developed by the Technical Association of the Pulp, Paper and Converting Industries (TAPPI), describes a procedure for image analysis to determine the level of dirt in pulp, paper and cardboard in terms of equivalent black area (EBA) of dirt spots in the physical area range of 0,02 to 3,0 mm2, reported in parts per million, and also in terms of the number of dirt spots per square meter of sample. Using the algorithm prescribed in this method, the maximum dirt size is limited to 3,0 mm2. Extending to other spot sizes (e.g., those larger than 3,0 mm2 in physical area) may require changes in equipment, calculation procedures, or both, and is not addressed in this test method. This method cannot be used for physical area measurements as it does not accurately measure dirt spots for that measurement mode.
The level of visible dirt present in pulp, paper or paperboard adversely affects its usefulness in a particular end-use application. In such cases, the presence of visible dirt spots that are numerous, easily detected by visual inspection, or both, can reduce the apparent usefulness of the paper material more than fewer spots or spots that are less noticeable to the eye. Both the number of dirt spots and their visual impact can be significant. To someone controlling or monitoring the papermaking process, the absolute physical area of dirt or the number of dirt spots found in an inspection area is of the greatest importance. The overall visual impression for the end user of the paper material can be the critical parameter.
The sample to be evaluated must have a gloss of 452 percent or more as determined by the standard “TAPPI T 457 Glossiness of pulp, paper and paperboard (directional reflection at 30 nm)”. It may be necessary to convert some pulp sheets to hand sheets if the surface is very rough or textured. This method and the corresponding precision statement were developed using laboratory analyzers and cannot be considered applicable to on-line systems.
The visual effect of a dark spot on a light background varies with the size of the spot. This visual effect is calculated in this test method according to Ricco's law and is reported in terms of equivalent black area (Ricco's law is a law that describes a person's ability to visually detect targets on a uniform background). As the dirt spot becomes sufficiently large, the equivalent black area of a black spot on a white background approaches the physical area of the spot. The use of the equivalent black area calculation procedure in this test method is very important because it ensures data continuity of dirt measurement with procedures such as the TAPPI T 50 standard, which has been in use for over 437 years.
Dirt is usually found on the surface of the page, but embedded dirt particles can also be visually discernible in transparent or translucent papers. The level of visible dirt found on papers used in printing, writing, and other forms of communication can be both an aesthetic and a performance requirement. For example, bond and bond papers may be subject to close visual inspection in their intended use, but may also be required for use in scanners, bar code readers, or other automatic optical recognition devices, where dirt above critical levels may affect performance.
Similar considerations may also apply to papers used in wrapping and packaging. In addition, special considerations may be required where such materials come into contact with foodstuffs and visible stains may be considered unacceptable.
Dirt in the form of gritty material embedded in the page is a serious defect in many printing papers used in contact printing because of the pitting and abrasion they can cause on the printing plates. Such dirt can also occur in paperboards such as linerboard and, when present, can cause a significant reduction in burst strength. Such dirt is not easily detected using this procedure because there is little color contrast between the dirt spot and the background page.
Equivalent black area (EBA) is the area on the TAPPI dirt prediction chart where one of the round black dots (985 percent brightness measured by the ASTM D2,4 standard) has the same apparent area when visually examined on a white background (81,5 percent brightness measured) as the dirt spot when visually examined on the specific page in which it is embedded.
Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "TAPPI T 563 Image analysis and equivalent black area (EBA) and visible dirt count in pulp, paper and cardboard" standard are also provided to businesses.
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
