Utrasound imaging might have a future in horse-gear manufacture

Agricultural Research Service engineer Cheng-Kung Liu, left, observes the airborne ultrasonic system used to scan hides for defects while another engineer with the service, Nick Latona, reviews scan images. Photo: Zerlina Muir
Agricultural Research Service engineer Cheng-Kung Liu, left, observes the airborne ultrasonic system used to scan hides for defects while another engineer with the service, Nick Latona, reviews scan images. Photo: Zerlina Muir

Makers of quality leather riding gear could one day be relying on ultrasound images of hides to avoid hidden imperfections in their finished products.

The Agricultural Research Service, a division of the US Department of Agriculture, says one of its scientists has found a way to spot defects in the animal hides that are processed into leather goods, from shoes to horse gear.

The global leather industry is substantial. In the US alone, 90 percent of the 32 million hides produced by its meat industry each year are exported.

Before they are sold in international markets, they are visually inspected, weighed, and given a numeric grade.

Many hides, however, have hidden defects caused by insect bites, abrasions, scars, and natural rough spots. Such defects can sometimes make it hard to tell the difference between a high-quality hide and a lesser one.

Processing and selling animal hides is a $2 billion industry in the US, and the lack of any technology for measuring defects and characterizing quality often leads to disputes after the hides are sold, says Stephen Sothmann, president of the US Hide, Skin and Leather Association.

Having technology that meets these needs would give US exporters an advantage over foreign competitors and bring higher prices for US hides.

American hides are widely considered to be a premium product in global markets, but foreign competition is intensifying, and “it’s important that we remain on the cutting edge in terms of quality,” Sothmann says.

“We need to be able to take the guesswork out of evaluating unfinished hides, so that we can accurately and objectively predict the quality of the leather product that can be made from them,” he adds.

The scientist who made the breakthrough is Cheng-Kung Liu, a materials engineer based in Wyndmoor, Pennsylvania.

An ultrasound image of a steer hide reveals a defect, in red. Image: Cheng-Kung Liu and Nick Latona
An ultrasound image of a steer hide reveals a defect, in red. Image: Cheng-Kung Liu and Nick Latona

His solution is the use of ultrasound. When transmitted through an object, any defects or rough spots on the object’s surface will change the intensity of the signal. This means surface defects which may be invisible to the naked eye can be identified.

Ultrasonic waves are already used to grade lumber and identify defects on aircraft parts and other precision materials, Liu says.

Liu, who began working on the problem at the request of the Hide, Skin and Leather Association, adapted existing scanning technology so that it can detect defects in animal hides.

In recent tests, he scanned hides by sending low-frequency airborne ultrasonic signals through the hides to a receiver a few centimeters away.

His scans collected enough data to accurately assess defects, and predict the potential quality of the leather’s toughness, strength, stiffness, and other factors. The scans did not cause any damage to the hides.

His findings were published in March in the Journal of American Leather Chemists Association.

The scans took about 20 minutes, but Liu has since bought upgraded equipment that cuts that time in half.

Because the equipment is based on commercially available technologies, he anticipates having a scanner available for industrial use in two or three years.

Reporting: Dennis O’Brien

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