Spanish Physicists Focus on Fuzz

Daniel Woolls

Fuzzballs on sweaters and other garments are an inescapable fact of life. They detract from a garment's appearance and make it look old before its time. Now, at least, researchers in Spain have discovered a way to study them without squinting.

A team at the Universidad Politécnica de Cataluña, which is located in Spain's top textile-producing region, is studying pilling, the formation of bunches or balls of tangled fibers on the surface of a fabric. The researchers claim that their digital image analysis of fabric quality produces results that are as good as or better than those from the traditional method: experts poring over photographs with their naked eyes.

The new method, which was described in the June issue of Optical Engineering, illuminates artificially pilled samples with a near-tangential beam of white diffuse light from six polar angles. The researchers examined 32 samples in a range of fabrics and colors, from a dark blue knit to woven yellow twill.

No humans needed

The images were obtained with a CCD camera and digitized at a resolution of 512 × 512 pixels and at 256 gray levels. An image-analysis algorithm yielded a single, information-rich picture and detailed numerical data on the surface area affected by pilling and the density of fuzz. Humans eyeing photos of pilling can give only qualitative estimates of these two features.

The technique has the advantages of being automatic, free of human subjectivity, more detailed and repeatable. The downside is that it is relatively slow -- 5 to 7 minutes to analyze a sample. The researchers believe that a low-level, computer-friendly programming language could shortened this. "In fact, we have already sped the process up considerably," said María Sagrario Millán, who devised the technique along with Héctor C. Abril and their Colombia-based colleague, Yezid Torres of Universidad Industrial de Santander.

Millán said the team hopes to market the device and has made preliminary contact with a German firm that manufactures machines in which fabrics are tumbled or treated with abrasives to simulate worn clothing and carry out pilling tests.

"We think our research has evolved to the point where it can be used to build a device for industrial use," she said.