Dirt and Size Estimation Charts
TAPPI has a solution for dirt -- the kind that gets into your products during the manufacturing or shipping process.
TAPPI’s Dirt Chart cards estimate the equivalent black area (EBA) of dirt or other colored specks. The equivalent black area of a dirt speck is defined as the area of a round black spot on the white background of the TAPPI Dirt Estimation Chart that makes the same visual impression as the dirt speck on the material in which it is embedded. They are manufactured from an original negative produced on DuPont CRR film and processed on a rapid-access processor using Kodak/Fujifilm chemistry. Each card is produced on photographic paper via a contacting frame with a NuArc light source and NuArc light integrator that controls the specific exposure designated for accuracy and consistency. To ensure the accuracy of the charts, each piece is measured by examining the .20 dot with a 100 x magnifier that has a reticle (scale) incremented in 5/10,000 mm on the lens. This opaque chart can be used with TAPPI Test Methods T 213, T 437, and T 537.
You want to hear more? Check out TAPPI’s size estimation chart (for use with Test Method T 564). Developed from the TAPPI Dirt Estimation Chart, this transparency is used to measure the size of spots, defects, or inclusions over the range of 0.02 to 5.00 square millimeters in paper and other industrial materials such as textiles or plastics.
For quality control applications where exact dimension specifications are required, the TAPPI Calibrated Size is now available.