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What does the onion bag have in common with blood dialysis machines? One man: George S. Nalle Jr.

Nalle's invention, Naltex, was a way to extrude nonwoven plastic netting directly. The nets also have been used as mesh guards to protect young trees and as a component of equipment to purify water.

Nalle hails from Austin, Texas. That's where he started his company, Nalle Plastics Inc., right after World War II.

``My father was born in Austin, Texas. My grandfather was born in Austin and my great-grandfather was born in Austin, Texas,'' he said.

The company started out doing injection molding, then got into extruded netting in the 1960s.

Nalle, 77, became interested in plastics while a senior at the University of Texas. After earning a physics degree, in 1941 he joined the technical school at the U.S. Air Corps, later renamed the Air Force. He finished up Dec. 5, 1941, two days before Japanese bombers attacked Pearl Harbor.

Nalle became immersed in the world of plastics during WWII, while on assignment in New York. His colonel, R.W. Kenworthy, was involved in procuring plastic parts for the proximity fuze, a huge-volume device that dramatically increased the destructiveness of U.S. missiles. Nalle helped on this and other projects, such as improving electronic equipment for aircraft.

During the war, Nalle met Bill Cruse, the leader of the Society of the Plastics Industry Inc., who compiled industry reports for the War Production Board.

``He was an excellent friend,'' Nalle said of Cruse, who died in 1993.

Right after the war ended, Nalle represented the Air Force on a team sent to study Germany's plastics and chemical industries. The Germans ``were advanced in their chemistry, but on applications we seemed to be ahead of them.''

Nalle saw his first twin-screw extrusion machine. His interest in plastics grew sky-high.

``I was already convinced that this was the way to go. I got out of the Air Corps, put on permanent leave at Thanksgiving of 1945, and I had my first injection molding machine on a veteran's priority in the spring of 1946. From there I continued to grow, at first making housewares.''

Nalle Plastics Inc. was born. One early product: spring-hinged clothespins. The company spent the rest of the 1940s and 1950s injection molding. Then Nalle caught the bug, literally, for the product that would make him famous, plastic netting. Back then mosquito netting was made with relatively expensive copper.

``I was trying to make plastic insect screening, but it was never a successful use of net because Mr. Pussy Cat would climb it. There was little or no load sharing. The filaments would break sequentially, whereas if it was a woven net, they would pull down and unify,'' Nalle said.

But the work proved that a bilayer net could be extruded without the knots common to woven metallic or synthetic fibers.

Nalle's process used a pair of concentric, counterrotating dies at right angles to the extruder. Whenever the die holes crossed each other, the hot filaments coalesced and joined together. He patented Naltex (using the first three letters of his last name and the first three letters from the state of Texas) around 1960.

Nalle also developed a quenching bath and specially designed take-off equipment.

``While it never worked out as a screen insect mesh, the fallout was tremendous,'' he said. ``The biggest fallout was the work with Baxter Laboratories for the artificial kidney. Baxter saw some of our literature and they came to see us in Texas. From then on, we were in. We were in because our netting was highly biplaner and gave low resistance to blood flow.''

Nalle Plastics began making products for Baxter in the 1970s.

Naltex also was used to support special membranes in dialysis machines to purify blood. The semiconductor industry used the netting to make ion-free water.

Naltex tree seedling guards were used widely. The old metal guards had to be removed when the tree began to grow.

``Our netting, by the use of the proper amount of inhibitor, could be made to break up in anywhere from one year to four years,'' he said.

He sold Nalle Plastics to U.S. Netting in 1987. He holds 26 U.S. patents.

``We're still making netting. The factory's still in existence.''