Nathan Lester & William (Bill) Morris Lester – The Origins Of Modern Injection Molding And Pyro Plastics Company

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By Alan Bussie Google+ profile

Second Edition Notes

In the first edition, credit was given to one man for the first modern injection molding machine.  This may or may not be true; evidence gathered over the last 3 years paints a more complicated picture. This revision is not an effort to take credit away from anyone but to give it where due.

 I would like to thank artist and friend Michael Boss, Peter van Lune, Marsha Frantisak and the “Industry Watch” article cited below.  Without these sources this article would not be possible.  Marsha is niece of William Lester and granddaughter of Nathan Lester.  Please note that any photos without credits are from the internet.  If you did not receive credit or if any of these photos are copyrighted, please contact me for credit or removal.  Thank you-AB


Pyro is not the most famous of the US plastic model companies.  Die-hard collectors know the name well, but even fewer are aware that Pyro’s founder, William Lester, was an entrepreneur, innovator and inventor.  Furthermore, William learned molding from his father, Nathan Lester.  Both of these men had a hand in inventing the modern plastic injection molding machine, which completely revolutionized American plastics manufacturing.  Some details are lost to history but enough is known to create a rough portrait.


Modern Injection Molding Machine (courtesy Western Kentucky Plastics)


William’s father, Nathan Lester, was born in 1884 in Minsk, Russia and immigrated in 1905.  Bill’s mother, Mrs. Gussie Lester, was also born in Russia in 1884.  We do not know much else about his youth, but Nathan was a brilliant man and entrepreneur who reached the top of his industry.  He owned Lester Die & Machine Company of Cleveland (1920s to ?, referred to as ‘Lester Tool’ later), Lester-Phoenix Die Casting Machines in Cleveland (30s/40s+), one of the leading die-cast companies in the USA.  At least one trade catalog (dated 1941) of Lester-Phoenix Die has survived.  He also owned Lester Engineering and held numerous patents.  This is a small sample:

  • Pneumatic die-casting machine filed as early as 1926
  • Plastic Casting Machine filed April 15, 1938 and granted June 3, 1941 by the Patent Office
  • Link mechanism for pressure casting machines filed as early as 1939
  • Injection molding control apparatus filed in 1943
  • Injection molding machine spreader filed in 1944

In the book “The Story of New Jersey(1945),” Nathan is credited as being one of the “leading die casters in the United States” and heading a company (identified later as Lester-Phoenix) which “…builds die casting machines and different types of plastic moulding machines.”   Paul Orban, the second engineer hired by Lester Engineering (and later chief engineer) said that “He was a pleasant man to work with, a chain smoker, and he paced like a lion in a cage in the engineering department.  He was cordial and honest. Nathan was originally a tool-and-die maker. He worked for Reed before starting his own company.”

Nathan’s son, William Morris Lester, was born in Brooklyn, New York on Jan. 14, 1908. He attended Brooklyn public schools and graduated high school in Worchester, MA in 1904.  His father’s business impacted him early; William was still in school when he started designing molds and casting machines.  After high school he enrolled in Worcester Polytechnic Institute.  He graduated in 1928 with a BS in Mechanical Engineering and extensive background experience in die casting machines and mold design.


Worcester Polytechnic Institute

His first job was Developmental Engineer for Precision Castings Co., Syracuse, NY.   After almost three years, his entrepreneurial spirit prompted him to leave in 1930/31.  Bill went to his father’s shop, Lester Tool and Die Company, and Bill’s first job was Chief Engineer. Bill did own stock in Lester Tool, but it is unknown if he bought the stock before or after he became an employee.  Bill designed molds and die casting machines for Lester, and Reed-Prentice Company manufactured the machines under license.  Bill increased the efficiency of mold making through numerous improvements and attachments for tool- room equipment.  He received several patents for these innovations in pressure and die casting equipment.  Given the early dates (from the 1920) of Nathan’s patents and his leadership in the field, his son certainly learned the practical engineering and the business sides from his father.  Bill worked about four years at Lester Tool.   As we will see, he was a very fast study.

 Bill married Betty Lubarksy of Brooklyn, NY on Sept 2, 1934.  In 1935 Bill was invited to participate in the start-up of Commonwealth Plastics Company.  The new joint venture was based in Leominster, MA.  To earn his equity stake in the business, Bill had to design, build and perfect a commercial plastic injection molding machine in 10 weeks. 

To put this task in perspective, the only machines that existed at this time were:

  • The Eckert & Zeigler hand press
  • The H.P.M. hand press
  • Isoma electric press 1-oz. capacity
  • Ucholz hand press

None of these machines could meet the cycle time or precision for modern mass production since they were hand operated or of low capacity.  Given his education and background, Bill was the man to get the job done.

The deadline was made.  The ‘Lester Machine,’ the first modern injection molding device, was born.  Melted plastic was injected with thousands of pounds of hydraulic pressure into engraved metal blocks joined together like a closed waffle maker.   The machine had a capacity of 4 ounces.  The Lester machine did the same work as existing machines, but better and in only 6 seconds.  Larger injection molding machines were already being used (primarily to mold rubber) but they took several minutes to create a finished part. 


There is a debate about the origins of the Lester Machine.  It started with an article written for the New York Times by Jennifer Bayot on March 16, 2005.  It opened with: 

“William M. Lester, who revolutionized the plastics industry 70 years ago with his design for an automatic molding machine, died on Saturday at his home in Delray Beach, Fla. He was 97.”

This article prompted one dated May 31, 2005 from “Industry Watch.”  In this piece, Don Lewis, formerly a salesman for Lester (and eventually the president) states “Nathan Lester started the company and, as far as the injection machine design goes, Bill had nothing to do with it, He may have sold machines for his father, but his father was the brains behind Lester.”  Bill Jaeckel was also a salesman for Lester and later for Reed.  He states “Nathan Lester started it all. Nathan was the heartbeat of Lester Engineering.”   Mr. Orban states ” “Bill helped his father, though I’m not sure to what extent.  His daughter, Mae, helped, too.  She worked at the drawing board. But Nathan was its originator.”  The article’s author (who is not named) sums up his (or her) reaction to the NYT article:

“…it… says he (Bill) ‘designed, developed, and constructed first full automatic injection molding machines.’ That may have something to do with the mainstream media’s confusion. John Kretzschmar, chairman of the Plastics Academy, offers his opinion. ‘The reporter I spoke with had no clue of the industry and knew even less about what injection molding is all about,’ he says. ‘I know [Bill’s] dad was with him in the company, but I honestly don’t know who invented the Lester machine.’  The former officials, employees, and customers of Lester Engineering say they do.

So should Bill be stripped of all credit for designing the first modern injection molding machine and revolutionizing the plastics industry?

Fortunately, we don’t have to rely solely on the “Industry Watch” article.  It was freely acknowledged in 1945 in the book “The Story of New Jersey” that Bill had a significant if not key role in the first injection molding machine and factory:

In 1935 William M. Lester started the first injection molding plant in Leominster, Massachusetts, for the Commonwealth Plastics Company, and he became the designer of the first commercially used machine for injection molding operations.

It is worth noting that this information pre-dates the NYT article by well over 50 years and was never disputed until the 2005 obituary.   

Furthermore Bill was inducted into the Plastics Hall of Fame in 1986.   I seriously doubt that a man with no technical ability or industry leadership would have been elevated as such.  Clearly Bill’s peers thought that he should receive some form of credit and it was provided to him.  At that time there plenty of people still alive who remembered when the plastics industry was born.  Yet again there was no controversy.

No one is debating that Nathan Lester was a brilliant man, the founder and heartbeat of Lester Tool.  But to state that his son Bill only “…may have sold machines for his father” is at best a curious statement.  No available history agrees with that.   If Bill was simply a salesman masquerading as an engineer, he would have failed when he struck out on his own.  But he succeeded.  From numerous sources we know that Bill Lester created important designs like cam core pulls, wedge blocks, and rack-and-pinion core operations. He was the founder and GM of two custom molding firms and holds original patents on tamper-proof packaging designs.  But even well before those accomplishments, his large number of patents attest to his engineering prowess.  Here, for example is one of Bill’s patents dated submitted  in 1935 -US Patent 2112342 for a Pressure Casting Machine.  And there are more and older patents.


(click to enlarge) 

No one is debating that Commonwealth Plastics was the first viable injection molded shop, courtesy of the Lester Machine.  It is no exaggeration to say that it revolutionized the plastics industry.  So who really built and designed the Lester Machine?

  • Was Bill capable of building the Lester Machine?   No one could argue that Bill made it in his kitchen or basement; the only logical place to make it would be at Lester Tool, where Bill owned stock.  Mr. Orban’s account strongly supports a family effort.
  • Was Bill capable of designing the machine?  At this point in his career he was.  On Feb 7, 1935, William M. Lester filed for a patent for Pressure Casting Machine (metal). The patent was granted with Bill as the inventor.  He has similar patents dating back to 1931 and earlier.  From the records, Bill was an accomplished engineer.
  • Would he get help from his father?  Bill and Nathan had a history of cooperation on major machines.  For example, they are listed as “Inventors William M Lester, Lester Nathan” for US Patent #US2112343A for a Pressure Casting Machine.  They owned a business together.  Bill’s father was a nationally-recognized expert in die casting and held numerous patents on casting machines and more.  Bill studied under him, designed machines and owned a business with his father.   Even Mr. Orban states that “Bill helped his father, though I’m not sure to what extent.  His daughter, May, helped, too.”  Clearly there was a great deal of cooperation.
  • Was it a cooperative venture?  Clearly it was.  Nathan was an incredible businessman and Bill proved to be one as well; if the machine worked, the company they owned would build and market the Lester Machine.  There was certainly no animosity over the machine or the results.  It was quickly integrated into the family business.  This is reminiscent of Nathan’s past employment with Reed.  When he had his own companies, he had Reed build his designs under license!

It is safe to say that Nathan was deeply involved in the design of the Lester Machine and Lester Tool probably manufactured it.   How else would Nathan, Bill and sister May be working it together, as the only eye-witness recounts?  No one had more experience or creativity than Nathan, and Bill, as chief engineer, was also clearly qualified and experienced.  Furthermore, Bill’s equity stake in Commonwealth was on the line.

We will never know the exact contribution that each man made.  Both were very dynamic individuals.  Given their business relationship, it is impossible that the Lester Machine was not a team effort.  Credit belongs to both great men.  Modern technology is not formed in a vacuum; it is the aggregate knowledge of the past coupled with our current drive for improvement.


As soon as the machine was practical, Nathan began producing the new machine at Lester-Phoenix.  Commonwealth also sold this machine across the country.  Very shortly, international companies heard of this innovation and got on the bandwagon.  Father and son got it right the first time – even today, injection molding is one of only two primary ways of making plastic parts or products.  (The other method is extrusion, which is primarily used for large items.)


Jumpin’ Jiminy Lapel Pin from Commonwealth Plastics

With the Lester Machine available, plastic materials technology began to expand.   It is important to note that before the Lester Machine, very few things were ever made of plastic.  John Kretzschmar, chairman of the Plastics Academy said it best:

“It just started an immense industry.  There are your car parts, your appliances, your pens, your snow shovels. You know, combs used to be made of deer horn.”  

1948-engel-hand-press.jpg                                             negri-bossi-1-injection-machine-1940s.JPG 

1940s Engle Plastic Hand Press and Late 1940s Negri-Bossi Injection Molding Machine 


Pyro Plastics Corporation

Bill was anxious to show the world what could be done with the new plastics industry.  In 1939, with war already underway in Europe, he founded his own molding company, Pyro Plastics with his first wife, Betty (who died in 1993).  Bill chose the name ‘Pyro’ because he wanted a short, catchy name that reflected the heat of the injection molding process.  Pyro’s first location was No. 526 North Avenue East in Westfield (Union), NJ.  Initially there were 50 employees.  Pyro quickly became a leading contractor of custom made parts and products in plastic.  During the war, Pyro, like everyone else, made parts for the defense effort. Some of these included aircraft parts, such as ventilator tubes and nozzles for P-47 Thunderbolts. 

pyro-trade-add-ii.jpg    pyro-trade-add-jan-1944.jpg 

Pyro Trade Magazine Advertisements, Dec 1943 and January 1944 (click to enlarge)

 In 1945 Pyro eagerly moved into post-war civil production.  The entire range of products is too great to list so I will name just a few.

  • A dustpan called “OtiH Pan of Styron” which “…retains it’s shape, rigidity and appearance through long use.  Lip can be held close to the floor.  Highly saleable in choice of colors”. 
  • Pyro teamed with corporations for numerous promotional items.  One example is Planters Peanuts.  Pyro  produced the very collectible and colorful ‘Mr. Peanut’ salt and pepper shakers, Mr. Peanut child’s belt buckles, Mr. Peanut children’s knife, fork and spoon set, Planters ‘bin’ delivery trucks,  Mr. Peanut cups and much more! 
  • Doll house furniture, poker chips, pan flutes and whistles in every shape imaginable. 
  • In the late 1940s, Pyro branched out into their own line of toys with pistols.  During the Korean War years, they became a leading manufacturer of toy soldiers, jeeps, tanks, trucks, amphibious vehicles and similar accessories. 

pyro-21-pc-military.JPG    pyro-21-pc-inside.JPG

Pyro 21 Piece Military Set (click to enlarge)  

  • As the Golden Age of Space toys (early to mid 1950s) got underway, Pyro was a major player.  They designed and molded spacemen, futuristic weapons and spaceships.  One of the most famous lines of spaceships was the four-rocket set including the X-100 Space Scout, X-200 Space Ranger, X-300 Space Cruiser and X-400 Space Explorer.  Four vehicles today that are valuable collectibles are the Pyrotomic Energizer, Rocket Car, Pyrotomic Fire Control Car and Rocket ship.  These were sold in bins or in groups with very graphic and colorful box and card artwork.


Pyro Four Spaceships Box and Contents (click to enlarge)

  • One of the most famous guns was the Pyrotomic Disintegrator.   The toy weapon is in great demand today, especially in complete, unbroken condition. 

pyro-gun-from-atomicboxdotnet.jpg   pyro-gun-from-atomicboxdotnetii.jpg  pyro-pistol-patent.jpg


Pyro Disintegrator Pistols and Patent Drawing – Courtesy of  (click any to enlarge)

pyrotomic-dis-rifle-patent.jpg  pyrotomic-disintegrator-rifle.JPG

 Pyrotomic Disintegrator Rifle and Patent Drawing (click to enlarge)

  • One consistent money maker for Pyro was the relatively generic and inexpensive ‘bin’ toys molded in colorful plastic and available almost everywhere.  Cars are among the most collectible ‘bin’ toys today.  

pyro-army-truck.JPG  pyro-bin-truck.JPG  pyro-log-carrier.JPG

Two Pyro Bin Trucks and a boxed Pyro Log Truck (click any thumbnail to enlarge) 

The plastic industry exploded in size and Lester’s reputation was world-wide.  The new versions of the original “Lester machine” remained cutting edge.  From the excellent space toy history book “Blast Off!” by Mark Young,

“Pyro’s injection molding machines were cutting edge.  Harry Kleeman (of Kleeman plastics) first saw cutting edge molding taking place – on Pyro produced machines in a Luxor factory.  “The secret of these fast machines was that they used a single cavity mold that was water cooled.  In addition, the products produced were made of wafer-thin plastic.  I can’t remember the sizes of the slices, but it was approximately 1/22 of an inch.  In those days, their production method was a sensation.  We were so impressed that my cousin Derrick, the managing direction of Kleeware, went over to America fairly rapidly and did a deal with Bill Lester.  We bought a half dozen of these machines and installed them.  It transformed our way of thinking.”


Pyrotomic Toys Ad (click to enlarge)

In 1952 the Gowland/Revell Highway Pioneers burst on the scene, launching the modern hobby industry.  Since Pyro’s first assembly kit came out in 1952 or 1953, we do not know if Pyro pre-dated the Pioneers.  But regardless, Bill certainly took note.  As the Gowland presses (possibly Lester Machines!) ran 24/7 to meet demand, Pyro expanded or entered the hobby market.


One of Pyro’s First Plastic Assembly Kits – US Navy Cruiser (click to enlarge)

The first kits were US Navy ships, followed by small box-scale sailing ships.  The initial kits were nicely molded but had few pieces and a ‘toy’ feel to them.  The success of these kits prompted Pyro to improve detail and expand into

  • Larger Scale Ship Models
  • An expanded line of historical small scale ships
  • Civil “Ships of the World”
  • 1/32, 1/24 and 1/16 scale classic automobiles, motorcycles, scooters and custom cars and bikes 
  • 1/1200 scale ships
  • Intermediate scale historical ship models
  • Full-scale pistols, handguns and rifles
  • Aircraft
  • Human Figures, birds, dinosaurs and human anatomy
  • Miscellaneous kits such as the Eiffel Tower and Design-A-House

The vast majority of these kits were from original Pyro molds, although some 1/1200 ships were from Eagle and most of the aircraft from Inpact.


Pyro 1/1200 Scale British Cruiser (circa 1963)

Meanwhile, Pyro’s bread and butter contract work continued.  One famous example is Lionel.  In 1958-1959, Pyro produced 8 military vehicles for them in ‘O’ scale. These now valuable train accessories included a sound truck, tank and Navy flatbed truck.


One of the Pyro-Lionel Pieces (click to enlarge)

As was common practice at the time, Pyro maintained a permanent NY showroom to display their products.  The showroom was certainly in operation in the late 1950s, but it is not known when it was first opened.

In February 1960, Pyro moved to 16 Pyro Park, Union, NJ.  The reason for the move is not known, but they may have outgrown the old location.


The Pyro Plant in 1963 (click to enlarge) 

Pyro grew to be an important part of the large and diverse Lester family enterprises.  In the meantime, Bill was a prominent member of his local community.  He was a member of the Chamber of Commerce for East Union County, NJ, the Westfield Rotary Club, Sigma Omega Psi and Fayetteville Lodge (NY).  He organized and became president of the Union County Lodge of B’nai B’rith.   Pyro even sponsored the very first Union, NJ Little League team (‘The Braves’) in 1954.    Being one of the most innovative and important players in the new plastics field, he was a member of the Society of Plastic Engineers and the Society of Plastic Industries.   Lester was a founder of the American Technion Society and the U.S.-Israel Plastics Corporation in Holon, Israel


The Cover of Pyro’s 1971 Catalog (click to enlarge)

Sale To Life-Like 

Bill led Pyro until its sale to Life-Like in 1972.  Life-Like had its origins in the 1950s making ‘Lifoam’ Styrofoam extruded ice chests.  Demand for the cooler was seasonal, so Life-Like needed another income stream.  The post-war boom in ready-to-run model trains caught their attention, and they successfully produced foam train tunnels for layouts.  This success encouraged Life-Like to create other scenery items and by the 1960s they added RTR rolling stock.  In the early 1970s they added yet another line by purchasing the Varney molds.   While looking into other hobby expansion opportunities, a deal was struck for Pyro in 1972.  Initially, Life-Like marketed Pyro kits.  The Life-Like boxes sported Pyro part numbers and one box top side panel said ‘Made Under License From Pyro Plastics Corp, UnionNew Jersey‘.  Pyro had been at work on new molds for the 1/32 car line, and the first issues were made in this fashion.  This has incorrectly led some to believe that Life-Like cut these molds.  Within a fairly short time, the licensing deal ended and Life-Like took over production completely, issuing their own part numbers and sometimes new box artwork.  Around this time Life-Like purchased many ex-Adams molds as well and also reissued the Adams/Revell Miniature Masterpieces.

As you can imagine, Bill remained creatively active after the sale of Pyro.  As a consultant Engineer and President of TBL Development Corp, he worked on tamper-proof and tamper evident packaging for foods, drugs and drinks, and the special mold tooling they would require for mass production.  He obtained more US patents on a rotary internal combustion engine, high accuracy injection for die casting, a squeezable container that closed automatically and much more.  He and his two associates added more than 20 US and world-wide patents.

Bill did marry again and retired to Florida.  He was inducted into the Plastics Hall of Fame in 1986.  He enjoyed photography and golf in his spare time.  William M. Lester died on March 12, 2005 in Delray Beach, Florida.  He was 97 years old.


William (Bill) Morris Lester, 1908-2005


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