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Westmoreland's Opal Formulations

As Found in Brainard West's Notebook

by Charles West Wilson

Sam'l Brainard West was Westmoreland's Secretary from 1921 to 1937. This was the 16 year period when his father, my grandfather, Charles West was president of the company and essentially Westmoreland's sole owner. After studying engineering at Lehigh, "Brainard" West began a career in Texas with Gulf Oil, but not for long. No sooner did he get to try on his first 10-gallon hat when he received a call from his father asking him to "Come back here and help me run the company." I understand my uncle took a keen interest in glass formulations, and a surviving Notebook of his would seem to bear this out. In it he recorded 84 formulations: 37 for crystal; 28 for transparent colors; one for black; and what most interests us here, 16 for milk, or to use the term of that era, "opal". While some were clearly those of other companies, the majority can be assumed to be Westmoreland's own.

We know all of Brainard West's entries had to have been made prior to August 1937 when the company underwent a change of ownership and Charles and Brainard West left together. There is an importance to that cut off date beyond Westmoreland's change of ownership, however. At the end of 1935, less than two years earlier, Dan Jenkins had retired. Since this highly regarded glassmaker had been Westmoreland's Superintendent from 1895 that is, almost from Westmoreland's beginning some of these formulas may be a unique surviving record of the glass of Westmoreland's earliest years. Before turning to Brainard West's Notebook, perhaps we can look back at some of the opaque glass chemistry of a still earlier time.


As most milk glass collectors already know, opaque white glass is believed to have originated in Europe (in 16th century Venice, according to most accounts) as one of several substitutes for expensive Chinese porcelain. In its early years it apparently consisted of crystal glass with the addition of china clay (kaolin) and bone ash (ground, calcined bones) for opacity. Since it later shared these ingredients with bone china, and in its semi translucency resembled bone china, it was sometimes referred to as "bone glass". Apparently, there were two shortcomings to this simple mix. First, depending on its source, the bone ash would impart inconsistent coloring, usually veering towards a cold gray. And second, if the batch was super saturated with bone ash and clay, the glass tended to be brittle; but if less was used, the glass appeared thin and opalescent. I am not certain whether the early opalescent glass of Sandwich was intended to be an imitation of porcelain or pottery, but the "opal" glass of Pittsburgh from the late 19th century surely was (despite the then universal use of this curious name). But then, this post Civil War glass contained fluorine. Nineteenth-century American glassmakers were apparently the first to add fluorine to the batch. This was first in the form of fluorspar and then kryolite, a mineral brought over "From Greenland's Icy Mountains." (I will follow Westmoreland's practice in the use of the "k" spelling for cryolite.) With fluorides, glassmakers were able to achieve their goal of a dense opaque white of a predictable hue. But this new whitening agent also had its faults. First, regardless whether tanks (heated from above) or pots (heated from the bottom and sides) were used for the molten glass, the fluorides would attack them. Over the years, many technical articles were written addressing this problem without really solving it. Second, the fluorides created an even more brittle glass with minimal workability. Glassmakers found that by adding feldspar and lead to their batch they could soften the glass and extend its working time. But these additives also created new problems. Feldspar, related to kaolin and actually used as early as the 16th century, was believed to aggravate the tank burn out problem. Lead was expensive, and for its cost it endowed opal with none of the aural and visual traits so cherished in crystal. Nevertheless, it managed to carry over to opal one of its failings namely, a hypersensitivity to heat and cold. The sensitivity of lead glass to temperature change may account for much of the opaque glass breakage that collectors complain of today. That, plus the natural tendency people have to treat like china anything that looks like china! It seems there has never been any one "best" formulation for opaque glass. All formulations are apparently compromises, and glassmakers have always had to make tough choices. Maybe this is why we find so many opal formulas in Brainard West's Notebook. Let's turn to it now.


The Notebook contains sixteen complete opaque formulas of which thirteen seem credible. While twelve of them have enough in common to allow us to group them together, the thirteenth is distinctive enough to require us to treat it separately. Finally, three, all labeled "Lead-Free Milk Glass", are probably spurious and we will save them for the end. Meanwhile, let us begin with the dozen that seem compatible.


The twelve were designated as:

  • Opal (2) 
  • White Opal (2) 
  • Blue Opal (2) 
  • Green Opal (1) 
  • H L Dixon White Opal (2)
  • 1928 Opal (1)
  • W G Co Opal (1) 
  • Opal Day Tank (1)

WEIGHT - Based on their weights, the first four formulas on the list were for pots (up to 1¾ T total). The last three were for day tanks (about 1000 lbs. total). And the two "H L Dixon" formulas were simply based on percentage weight. H L Dixon, oddly enough, was not a glassmaker, but the Pittsburgh glass furnace constructor who erected Westmoreland's second pot furnace in 1923.

SAND - The basis of all glass is sand. For the twelve, the sand weight averaged 53% of the batch weight somewhat less than for Westmoreland's crystal formulas where no opacifiers were used. Since all the Notebook formulas were based on sand weight - not total weight - I will base the other materials on sand weight, too.

FLUXES or ALKALIS  - These ingredients, together with lead and sand, constitute glasses "heavy chemicals". For the twelve, they consisted of soda, lime and potash ("pearls") just as I found they did in Westmoreland's crystal formulas. But there was an interesting difference. While I found lime in every Westmoreland crystal formula and potash in more than half, I found soda ash the chosen alkali in every opal formula, with small amounts of lime or potash supplementing the soda ash in just three. For all twelve, the soda ash averaged one third of the sand weight, and in all of them it fell within the "25% 40% range" for alkalis stipulated in various older accounts.

"NITRE" or SALTPETER - This oxidizer or "igniter" needed in all glass was included, as expected, in every one of the 12 in small amounts (6% or less).

LEAD - Used as a softener, lead was called for in three of the twelve, but strangely not the three with the highest preparation of fluorides needing softening, nor in any of those containing kryolite! In the three where it was found, the lead ranged from 6% to as much as 30% of the sand weight, but the form of the lead (litharge or red lead) was not stipulated. For those who may be curious, three of Westmoreland's crystal formulas contained lead.

FLUOR and FELDSPAR - Of the opacifiers or whitening agents, fluorspar was included together with feldspar in every one of the twelve formulas. Ordinarily we would expect to find twice as much feldspar used as fluorspar, but in six of the formulas they were in balance. The amounts of fluor and feldspar together ranged from 25% to an incredible 95% of the sand weights of the twelve. (The 95% was found in the W G Co Opal"). Not surprisingly, the preparations of these opacifiers and sand were inversely related in all twelve. What is most curious, though, is that the amounts of fluor and feldspar were no lower in batches where bone ash, china clay, or even kryolite (the alternate whiteners) were included.

KRYOLITE - This fluoride was included in just seven of the twelve and in significantly smaller amounts than the fluorspar, the other fluoride whitener. Unlike the fluorspar which, in the seven ranged up to 35% of the sand weight, the kryolite never exceeded 14%. This may be because kryolite is richer in fluorine.

In Westmoreland's December 1963 inventory, an amazing 9½ tons of kryolite was recorded. While this was more than a third as much as the inventoried sand, 1963 was the year Greenland's kryolite was exhausted, and I suspect the company had earlier bought up all it could.

CHINA CLAY and BONE ASH - While china clay was called for in seven of the formulas, bone ash was included with the clay in just four. Since the proportions of each ranged from only 0.5% to 5% of the sand weights, I was surprised to find a small amount of china clay called for in four of Westmoreland's crystal formulas, but even more surprised to find a small quantity of bone ash included in one of them as well.

MANGANESE - This "glassmakers' soap" was called for in only four of the 12 formulas. Even more surprising, I found it included in fewer than three quarters of Westmoreland's crystal formulations. This may be because it was added only as needed.

BLUE and GREEN - From the turn of the century, Westmoreland made both blue and green opal as well as white. There were several blues, but just one green which apparently resembled and has been confused with Greentown's "Nile Green". In the Notebook there are two blue opal formulas and a single green one. Both blues were made from powdered blue (dilute cobalt) and copper scales, whereas the green was made from iron scales. A little of these micro ingredients went a very long way. The "scales" used in all three totaled just one third of one percent of the sand weights, while the powdered blue came to just 1½ to two ounces in batches weighing up to 1¾ total tons each! I found these quantities of the powdered blue in several of the crystal formulas; I understand it was used to counter a straw-like color caused by impurities.

TRACE INGREDIENTS - I found small amounts of the following in just one or two of the twelve: zinc oxide, tin oxide, borax, alumina, antimony and carboxyl. Except for the tin oxide, all the others were included in the 1963 inventory. Since cullet (pieces of discarded glass) could be used in varying amounts in any batch, I have omitted it.


The preceding 12 formulas suggest Westmoreland achieved the dense creamy white of its opal from fluorides rather than from the phosphate in bone ash. And these fluorides came overwhelmingly from fluorspar. However, the 13th usable formula called "Ripley Opal" in the Notebook was the exception: it acquired all of its fluorine from kryolite. Since kryolite is richer in fluorine than fluorspar, only 10% kryolite was needed in this formula. This kryolite was "tamed" with large amounts of feldspar (35%) plus lead (6%).


These three "lead free milk glass" formulas are as frustrating as their name. Can they really be Westmoreland's? For one thing, "opal" seems to be the only term Westmoreland used for its opaque glass for over forty years before WW II. I understand the older workmen still called it "opal" up to the time the doors finally closed in 1984. For another, why would Westmoreland have singled out three opal formulas as being "lead free", when only four of the thirteen we just examined contain lead?

Let's broaden our major question: Can these three be anybody's? All of them start out with plausible amounts of sand, but for flux, two stipulate large quantities of potash one with essentially nothing else. Only one called for "nitre". Bone ash was the only designated whitener, but the quantities shown were all inadequate: one specified just 6%. All three included arsenic useful in countering yellowing, but yellowing should not be a problem with bone ash. Finally, one of them topped things off with 6% "common salt"!

Perhaps I am wrong. But these three made me think of Shakespeare's monument, Mozart's "Musical Joke", or the "What's Wrong With This Picture" challenges I can recall from my childhood. Were these sly formulas really meant to be taken seriously? Or were they meant to be taken with just a grain of (common) salt!