What does MacBeth-Evans have to do with Opal Pyrex and Corelle?

Monax, the opal glass formula produced by MacBeth-Evans since the 1920s, was fundamental to the development of Opal Pyrex in the 1940s.  And the plant in which Corelle was produced for decades was built on production technology also invented by that same company in the 1930s.

The MacBeth-Evans Glass Company was formed in 1899 with the merger of two Pennsylvania glass producers, the Thomas Evans Co. of Pittsburgh and the George A. MacBeth Co. of Charleroi.  Both companies were major manufacturers of glass lamp chimneys, but MacBeth was by far the larger with two more plants in Indiana.  The new company, headquartered in Pittsburgh and eventually Charleroi, soon grew again with the acquisition of a third lamp chimney maker in Toledo Ohio.  Within a year of the merger MacBeth-Evans operated five plants producing a total of 5 million chimneys a month.  They dominated the market not only in sheer numbers, but with top-quality products as well.

Clear coloured tableware made by MacBeth-Evans before the 1936 merger with Corning.  Pink American Sweetheart (R-pattern), amber Stippled Rose Band (S-pattern), green Dogwood.

Like Corning, MacBeth-Evans placed great importance on research and development, both in glass formulation and in manufacturing technology.  Although smaller than Corning, MacBeth-Evans provided strong competition with product lines often overlapping those of Corning.  These included headlamp and signal lenses for the rail, marine and automotive industries, optical glass, architectural glass and laboratory ware. 

More significantly, they also produced many different opalescent glasses for lamp shades and street light globes, an application which requires both mechanical strength and resistance to heat.  Monax glass, dating to at least the early 1920s, distinguished itself as exceptionally durable and heat-resistant with the ideal translucency and a clean white colour.  It was the perfect medium for many applications, and it was acknowledged to be the best in the industry. 

Monax Luncheon Plates - Petalware (left); American Sweetheart (right)

The company made their first steps into the pressed tableware market in 1929, and the early products were generally the clear pink or green variety which was typical of Depression glass.  Within a few years, the Monax formula would be employed for patterns like American Sweetheart and Petalware, among others.  Monax Ware stood out from the competition with impressive durability coupled with a delicate appearance.  A beige version of Monax, called Ivrene, was mainly used for Petalware.

By 1936 MacBeth-Evans was the world leader in opalescent glass and lamp glass, with a strong brand name in glass dinnerware too.  Since 1915 Corning's household products had been confined to clear borosilicate Pyrex ovenware, plus their latest innovation, aluminosilicate Flameware for stove-top use.  Neither opal glass nor dinnerware had been produced at Corning, and these were product lines into which they were ambitious to enter. 

MacBeth-Evans had recently developed and patented automated pressing equipment intended for making dinnerware, and this invention was especially interesting to Corning Glass Works.  Possibly reinforcing Corning's desire to amalgamate with their competitor that year was the fact that the rights on their borosilicate patent were expiring; MacBeth-Evans would have been just the company to introduce their own borosilicate ovenware to rival Pyrex.  The merger was finalized the 24th of December 1936 and the Charleroi plant would operate under the new name “MacBeth-Evans Division of Corning Glass Works”.

Monax: Demi-tasse in plain 'piecrust' design and American Sweetheart (not an official pattern name, MacBeth-Evans actually called it 'R-Pattern'.)

Now in possession of the technology for automated pressing machinery, Corning spent nearly $1M in 1937 constructing the Pressware Plant in Corning, N.Y., and production commenced on June 13 1938.  This new facility streamlined the manufacture of clear Pyrex ovenware, allowing the retail price to be drastically lowered, thus boosting sales.  This action was desperately needed as Pyrex was still unsuccessful in terms of profitability; its high price tag had been excluding it from the mass market.  Decades later, the Pressware plant would turn out billions of pieces of Corelle, but with newer and more complex equipment, naturally.

Wishing to focus solely on opal ware, Corning discontinued all MacBeth-Evans tableware patterns except for those made from Monax.  In the mid to late 1930s clear glass tableware was falling out of favour, and consumer taste leaned toward porcelain.  Another MacBeth-Evans glass formula, Cremax, successfully replicated the appearance of fine porcelain with the strength and low cost of glass.  Chinex is another off-white glass formula with a darker beige tone which becomes apparent when compared carefully with the creamy ivory tone of Cremax.  Chinex first appeared in 1938, and it might be the first opal formula to be developed by Corning Glass Works.

Cup & saucer, plain piecrust pattern in Cremax with Flora decoration.

Corning launched three new embossed tableware patterns in Cremax, Monax and Chinex glass with "piecrust" edges and various coloured decorations.  The embossed rim designs include Classic and Oxford, plus the plain ribbed piecrust rim which seems to have no official name.  Ivex is another new opal glass that appeared in the early 1940s in both Oxford and Classic.  Ivex is similar to Cremax, but with a more distinct yellow tone.

Printed decorations include a castle design, a red rose design, and three other florals: Bouquet, Flora and Princess.  The solid-coloured rim is called Bordette, and the lightly sprayed edge is Rainbow.  Undecorated sets were also popular, and gold trimmed pieces can be found as well. 

Apparently Corning's piecrust-edged patterns were produced until 1944, but it seems that Petalware was a mainstay until 1950.  Meanwhile, production of Monax lighting products also continued in Charleroi.

(Photo right:  Chinex at top; Cremax bottom.  It is a subtle difference certainly, but Chinex is darker than Cremax.  The difference can be seen more easily with a comparison, while reliably judging the colour of a single piece at a time is difficult.  This Chinex saucer is embossed with the Classic pattern, but some Classic pieces are made of Ivex, particularly those with coloured decorations.)


Both cup & saucer sets are in a plain 'piecrust' design, but they are clearly made of different glass.  Cremax, on the left, is more opaque with an ivory tint.  Monax, at right, is pure white and translucent.

In the early 1940s, Corning famously rose to the occasion with the development of Opal Pyrex tableware when it was discovered that ordinary restaurant china was not up to the task during the mobilization period of the Second World War.  While it is true that durable tableware was needed by the military, the need for stronger dishes became apparent in civilian cafeterias as well. 

Many diverse manufacturers found themselves in the war industry producing crucial equipment as quickly as possible.  This in turn dramatically increased the number of employees eating in factory cafeterias, and although wear and tear was a concern, the number of dishes needing storage revealed a greater challenge.  It was frequently necessary to store plates in ever taller stacks and even the sturdiest restaurant china would break under its own weight. 

Corning executives had always believed that the Monax produced in the Charleroi plant could be put successfully to other uses.  So by starting with the Monax formula and employing a specialized tempering process to strengthen it further, Opal Pyrex was invented.  When the new opal ware was put into practice, its impressive performance made it a huge success.

Opal glass had been under scrutiny for some time prior to this breakthrough.  A young researcher named Donald Stookey began his career with Corning in 1940.  As a chemist, his first assignment would be unravelling the mysteries of the company's newly acquired opal glass formulas.  His discoveries concerning crystallization and nucleation in opal glass formed the basis of a whole new field of science, and this placed Dr. Stookey on the path to discovering glass-ceramics in the 1950s.  The strength of opal Pyrex also can be attributed to minor crystal growth which occurs in the tempering process.

The Pyrex brand name shared by both clear Pyrex and opal Pyrex can lead to the erroneous conclusion that they are both borosilicate glass.  Opal Pyrex is not just whitened borosilicate, it is an opacified soda-lime glass and it is known as 'tempered opal'.  Borosilicate's claim to fame is its resistance to thermal shock, but in terms of mechanical strength it can be more fragile than tempered opal.  Conversely, tempered opal can take many bumps and knocks without breakage, and it possesses very respectable heat-resistance.  They are distinctly different kinds of glass, both with individual strengths and drawbacks, but in practical terms neither is clearly better or worse than the other.

Initially opal ware did not carry the Pyrex brand; it was named Pyrex when it launched in 1945 in the form of domestic kitchenware.  The glass-blower logo, also known as a gaffer and named 'Little Joe', originally had been the trademark of MacBeth-Evans.  They had not marked their products with the logo; it had been used mainly on letterheads, print advertisements, and packaging.  But this logo does appear on many opal products originating from Charleroi after 1936. 

(Photo: One version of MacBeth-Evans' Little Joe, on the base of a small piece of Pyrex restaurant ware.)

In terms of proprietary knowledge, the 1936 merger with MacBeth-Evans made a substantial contribution to the subsequent fortunes of Corning Glass Works.  Corning also gained access to important research that MacBeth-Evans had commissioned at the Mellon Institute.  Other benefits for Corning included key managerial and legal personnel from the MacBeth-Evans side who would play important roles in the years that followed.  Most notably the president and general manager, George D. MacBeth, became Corning's chief controller, vice-president, and member of the board of directors.


Related Articles:

MacBeth-Evans: Extra Photos 
1938 Pyrex Leaflet
Dates for Pyrex patterns/pieces: 1940s to 1950s, 1960s to 1980s

Sources: 
Imagining Consumers: Design and Innovation from Wedgwood to Corning,  Regina Lee Blaszczyk.

The Generations of Corning, Davis Dyer and Daniel Gross.

Corning and the Craft of Innovation, Margaret B.W. Graham and Alec T. Shuldiner.

Corning: A Story of Discovery and Reinvention, Davis Dyer.

New York Times Archives - various.