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Thank You, Extrusion!

Image: Allan Griff Extruded products
A few of our favorite extruded things: Film, sheet, pipe, wire, fiber, and a blown bottle.
Why should we be thankful for extrusion? Let me count the ways.

Thanksgiving month is an easy time to write my monthly article for PlasticsToday, as we have much for which to be thankful. I never forget my mother-in-law, Meta Kilsheimer Weis, who would often say, “Be grateful for what you don’t have!” Escaping to Argentina during World War II and succumbing to cancer at the age of 62, she knew what she was talking about. And all of you who have avoided or survived COVID-19, or have a case or maybe a death in your family, will know, too.

Now what does extrusion do to make us thankful? The following covers all the major branches of extrusion.

Pipe. Don’t take our safe drinkable water supply and drain and sewage lines for granted. PVC resists chemicals, doesn’t rust, stays smooth inside to maintain low-power flow, and can be solvent-welded or threaded for leakproof connections. It’s used for electrical conduits and channels as it doesn’t conduct electricity. In hospitals, corrugated plastic tubing in the ventilators and other devices keep us breathing and eating. Gas pipe, too, which I worked with for many years, is extruded, as is irrigation pipe used to grow our food.

Sheet. We now have clear protective barriers at market checkouts, in offices, and elsewhere. Formed trays protect our fruits and grow seedlings to make more food (and trees). Sheet is extruded for small stuff — drink cups and dairy tubs — and big stuff — refrigerator door liners, truck-bed liners, orange temporary fencing, strapping, pond liners, and small boats. And here’s one you never see: The little piece of carbon-filled sheet that protects electronic devices from overheating.

Film. Many millions of bags protect and carry our food, including the re-closable bags with (extruded) zippers. As for the reusables, they are extruded, too, using heavier film or woven strips. There’s house wrap and bubble pack; greenhouses and agricultural mulch; post office tote boxes, made by joining three layers of 5-mil HDPE film into corrugated board; the window in window envelopes. And don’t forget that protecting our food means more economical storage and distribution — in a competitive world, that means lower prices for all.

Coating. Lots of textiles, in cars and clothing, and tarps and roofing, too. And PE coating is what allows paper-pushers to make paper “bottles” and cartons. Paper and cardboard, for all their apparent sustainability, can’t sustain a life-cycle analysis that considers their greater weight and water-absorptive capacity (supporting bacteria, degrading to who-knows-what on the way to water, and greenhouse-gas CO2). As for the carbon footprint, if we do low-energy recycling — not chemical/advanced recycling, which breaks too many carbon-carbon bonds — we may be helping by using inert and safe plastics.

Wire and cable insulation and jacketing. This is my favorite example of how plastics are essential to modern life. Before plastics, tar, paper, and rubber (sort of a plastic) provided electrical insulation. Plastic insulation prevents loss in transmission (energy and fuel savings) and enables flame-resistant building wire and appliance cords in our homes, undersea cables across the Atlantic, and the protection of tiny wires in tiny devices. For a story on extrusion pride, look up the Battle of Britain, where the British repulsed the German attacks in 1940 because they had polyethylene to insulate radar transmission cables and, thus, “see” the enemy planes before they got there. It’s here, but they don’t know about the polyethylene part.

Profiles. This includes windows and doors that don’t need paint and won’t rot; house siding; the aforementioned zip on zipper bags; and big, rubbery expansion joints in concrete. Also, window and door seals in cars, plastic lumber, and even railroad ties. Hard to classify is the complicated tubing used in the medical world for catheters and other interventions. The industry distinguishes between pipe and tubing, even though both are (usually) round.

Filaments. Fishline and medical sutures. Brushes for teeth, paint, and street-sweeping. Nonflammable Christmas trees, some made on brush-making machines. Some rope and cordage. Netting, a now-common extruded product with many applications. Moving die parts are used to make structures for construction as well as the bags of onions and potatoes we see in the markets.

Fibers. The synthetics — nylons, polyesters, polypropylene, and so forth — for clothing and furniture and carpets. Also, our antivirus masks, some ropes, some nonwoven fabrics, replacing or mixed with agricultural products like wool and cotton. I avoid using the word “natural,” as it includes so many harmful things like viruses and hurricanes, but I am very interested in why people hang on to that word as desirable.

Extrusion/blow-molding starts with an extruded tube to make bottles for bleach and detergent, milk, fruit juices, and other beverages. Also, gas tanks for cars and other fuel-powered things, sometimes from two sheets rather than a tube, and safe packaging of agricultural chemicals, solvents, and building products (adhesives, paints).

Last but not least, we can’t forget the compounding extruders that make the pellets we use for all plastic processing, and the concentrates we need to add color, stability, and so many other properties to our materials. It’s this ability to change properties that make the plastiphobes uneasy. They don’t trust us, so it’s up to us to be clear what our products can and can’t do, keep to our spec sheets and claims, and earn our pride as extrusioneers.

So, in this time of stress, be thankful for plastics. Show gratitude for the good they do for us, as they “protect the things that matter, provide for those in need, so the next healthy generations can take seed.” (From the song “Like a Tree,” N H Shneiderman, 1994.)


About the author

Allan Griff is a veteran extrusion engineer, starting out in tech service for a major resin supplier, and working on his own now for many years as a consultant, expert witness in law cases, and especially as an educator via webinars and seminars, both public and in-house, and now in his new audiovisual version. He wrote Plastics Extrusion Technology, the first practical extrusion book in the United States, as well as the Plastics Extrusion Operating Manual, updated almost every year, and available in Spanish and French as well as English. Find out more on his website,, or e-mail him at

No live seminars planned in the near future, or maybe ever, as my virtual audiovisual seminar is even better than live, says Griff. No travel, no waiting for live dates, same PowerPoint slides but with my audio explanations and a written guide. Watch at your own pace; group attendance is offered for a single price, including the right to ask questions and get thorough answers by e-mail. Call 301/758-7788 or e-mail for more info.

TAGS: Assembly
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