Simanaitis Says

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“WITH ISINGLASS curtains y’ can roll right down/In case there’s a change in the weather.”—“The Surrey With The Fringe On Top,” from Oklahoma!, 1943.

What do you suppose “isinglass” was?


Oklahoma! ran for an unprecedented 2243 Broadway performances. It’s still popular in community and school productions.

Of course, it’s evident from context that isinglass was some sort of early transparent material for side curtains, but this only begs the question. In fact, the more one looks into isinglass, the less clear it becomes. Yet, having owned a car with side curtains (see, I am delighted to offer these observations.

In its primary definition, isinglass is a dried swim bladder of fish, primarily from sturgeon or cod. One of its uses is as a “fining,” a clarification agent, in the production of beer and wine. In fact, some vegetarians object to beers (such as Guinness and most stouts) that have been subjected to this process—it’s apparently acceptable with pescetarians (seafoods okay/other flesh not). Also, Kosher wines must use other than sturgeon isinglass because this fish is treif (Yiddish for “not kosher”).

Having cited Yiddish—and what an odd turn of events, eh?—I return to the lyrics in what might be their original form. Richard Rodgers and Oscar Hammerstein II wrote the music and lyrics, respectively, for Oklahoma!, and both of these gentlemen had some Jewish heritage.

In a somewhat iconoclastic but entertaining analysis, entertainment authority Danny Miller has suggested that these two might have originally composed lyrics in Yiddish, then reworked them in English. Consult to hear “Surrey With The Fringe On Top” sung in this language. I catch no specific mention of isinglass, but maybe you will.

A second meaning for isinglass relates to thin, transparent sheets of mica, a silicate mineral that sounds a lot closer to side curtain material.

Sheet mica.

Small windows in furnaces made use of sheet mica because of its resistance to high temperature.

Peepholes in boilers, stoves and the like used sheet mica because it was less likely to shatter than glass when exposed to extreme temperatures. It can stand up to 1650 degrees Fahrenheit, by which temperature, for example, sterling silver has melted.


Muscovite is the most common form of mica. It became a Russian art form in Muscovy-glass windows.

But isn’t mica a bit over the moon for simple side curtains, especially for those that “roll right down”?

On the other hand, early side curtains didn’t have wide expanses of transparency. Cars of the Brass Era (pre-1915) typically had leather or canvas side curtains with only small horizontal or vertical slots of (unspecified) transparent material.


Early side curtains provided weather protection, but not a lot of unrestricted vision. Image from Friartuck, Antique Automobile Club of America.

Familiar names like Plexiglas (brought to market by German/American company Röhm and Haas in 1933), Lucite (1936) and Perspex are all transparent thermoplastics of the PMMA (polymethyl methacrylate) family. Though Rodgers and Hammerstein might have known of these products when they wrote Oklahoma! in 1943, the names would have been anachronistic in its 1906 setting.

Today, Isinglass, Inc., founded in 2004,  is a producer of buffet, banquet and tabletop presentation ware. And boating people talk about “Eising Glass” curtains, though this seems to be just a corruption of isinglass.

Eising Glass is not to be confused with Dr. Eugene H. Eising. In Popular Science, December 1932, he was written up for exposing ordinary petroleum jelly to ultraviolet light, thereby creating an entirely new kind of healing agent. See The irradiated compound, “Radolatum,” was proposed for treating burns, boils, scalds—and even possibly cancer. “When more research has thrown full light on the ray phenomena, medicine will have new weapons to battle disease.”

And haven’t we come a long way from that surrey? ds

© Dennis Simanaitis,, 2013

10 comments on “WHAT’S ISINGLASS?

  1. Ray Unseitig
    September 2, 2013

    Nice reasearch, but not clarified yet. Next off to the car companyies manufacturing logs, and materials and processes. Then over to the museum to have some tests run on specimens. I’m guessing Rogers and Hammerstein are not the authorities on the subject. Still- how can we keep out of the weather when it gets nasty?


  2. Lynn Nadeau
    April 4, 2014

    I have a photo of an old old car, in a family album, that has the note “Buick, wooden spokes, mica windows.” Shows spoked wheels, and narrow vertical slit ‘windows:.

  3. Susan Winston, author
    May 14, 2017

    I have a buggy built in the late 1800’s with the original isinglass windows — that’s what my 103 year old mother called them. This was one of the three buggies /surries they drove on their family farm. The windows are like a thin plastic. My mother was not Jewish. I believe isinglass was the common term everyone used.

    • Thomas John OKeefe
      April 30, 2019

      Sorry, Susan. Plastic wasn’t invented until 1907. Your windows may well have been a retrofit with more modern materials. If not, I think you may have something else on your buggy’s and you might do well to preserve it.

      • Susan Shell Winston
        May 13, 2019

        I didn’t mean to say the windows were plastic. I said they were like a thin plastic — or rather a thick plastic. But they were isinglass, not plastic.

  4. simanaitissays
    May 14, 2017

    Responses to all three: Yes, it would be an interesting life-project to provide added clarity to isinglass. (Our little pun…). Yep, mica too. Last, my mention of Rodgers and Hammerstein and discovering the Yiddish rendition of “Surrey” were just too fascinating to pass up.

  5. markarnest
    October 10, 2017

    Fascinating speculation about the Yiddish, but surely wrong: Rodgers and Hammerstein borrowed the term “isinglass” from “Green Grow the Lilacs,” Lynn Riggs’ 1930 play upon which “Oklahoma!” is based. Hammerstein uses many of Riggs’ ideas in the lyrics.

    • simanaitissays
      October 11, 2017

      Thanks for adding this insight, not that it diminishes that wonderful rendering of “Surrey.” (How does one say “Si non e vero, e ben trovato” in Yiddish?)

  6. Larry F. Sommers
    April 29, 2019

    My father told me that when his father was well-to-do enough to own a Pierce-Arrow (before the Depression cut his wages), it had isinglass curtains. And I remember myself the old kerosene space-heater my other grandfather had in his living-room, with a circular window in front, probably 6″ in diameter, through which one could see the flames. I’m thinking it was probably isinglass, too.

  7. Wayne Martin Wilson
    October 1, 2020

    My father bought 1931 Ford Phaeton in College 1946. He said it still had the eisenglass side windows.

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