Carnival Glass: How It's Made and More

Carnival Glass Mould

To make Carnival Glass, you begin the process as with regular soda-lime glass.  You mix sodium carbonate (soda) with lime, silicon dioxide (silica) and other chemicals in a furnace and melt it to a molten state.  If the color of the glass is to be anything but clear, coloring is added to the mix.  Then you pour your mixture into a mould and let it take on the distinct shape and design.  Once it is cooled and molded the glass is removed from the mould and then reheated to add any additional features, such as a ruffled edge.

Closed Mould Ready for Molten Glass

Finally, the trick for the iridescent finish is sprayed over the glass while it is still hot.  The spray is composed of liquid metallic salts and the process of applying it is termed “doping.”  Metallic salt is the technical term for a compound composed of a metal and nonmetal.  They are ionic compounds, meaning they are held together by ionic interactions (positive and negative charges).  Regular table salt is an example of a metallic salt – composed of Sodium (Na+) and Chloride (Cl).  A few examples of the metallic salts used to provide iridescence were potassium phosphate, calcium fluoride, and sodium fluoraluminate.

Details on Mould

You may hear rumors regarding the toxicity of carnival glass due to the metallic sprays.  Though some of the chemicals used can be dangerous, they are not so once on the glass as a finished product.  However, in the article “A Lesson in Toxicity” by Dave Shetlar he states “Doping…is a very different issue.  Iron chloride and tin chloride when put into “mild” acids can produce some pretty toxic fumes when they hit hot glass.  In early factories, if the dope was sprayed without the use of a fume hood (as is done today), the doper and handlers may have been exposed to some pretty dangerous fumes.  However, I suspect that it was not really much worse than what was happening in the iron smelting, and steel manufacturing factories of the same period!”

Once the glass has been sprayed it is placed on a lehr.  This is a special machine composed of a covered conveyor belt.  The glass piece is placed on the belt and it passes very slowly through the enclosed area, allowing it to cool at a slow rate.  This prevents any temperature related stressors which could cause the glass to crack or lower its integrity.  For a whole 24 hour period the glass moves along the lehr until it is finally cooled to room temperature.

For collectors or enthusiasts, the identification of the carnival glass is as important and admiring it.  IMG_0053

Each of the carnival glass producing companies had distinct characteristics for their works.  It is therefore possible to discover where and what time frame a particular piece came from.  As discussed in our article on the History of Carnival Glass, the two main factors distinguishing one work of carnival glass from another are the pattern and the color of the glass.  When describing the color of carnival glass it is done in reference to the color of the actual glass upon which the metallic spray was added – not the color of the iridescent metallic spray.  For many pieces this can be determined by looking at the bottom, where often no spray was applied.  So when a piece is referred to as blue, it may not even look blue; but it is called so because the original glass without the metallic spray was blue.  The only exceptions to this are marigold, clambroth, white, and some smoke which are clear glass.


The main manufacturers of carnival glass were: Fenton, Dugan, Northwood, Millersburg and Imperial.  To identify a particular piece it is necessary to match the color and pattern to a known pattern of one of the manufacturers.  There are extensive libraries listing the 2,000+ patterns that were used.  It can be a cumbersome task, but based on the growing number of collectors – a rewarding one as well!  Please visit and for more information and resources on the spectacular world of Carnival Glass.

Carnival Glass: Reflection Upon the History of Iridescence

Imagine you are a young boy in 1918.  Your mother’s favorite new purchase is a vase, it is unlike any other vase – the color isn’t stagnant but shifts and shines in different tones.  She bought it from a popular company, Fenton, who called the style of glass “Venetian Art.”

Now imagine you are a young man in high school.  It is the early 1930’s and the Great Depression has transformed the country.  The unemployment rate is at an all time high. Your father has been out of work for some time and your family is barely surviving.  Pinching pennies; scrounging every cent that would help you survive another day.

Walking down the street one summer day you see a bright red poster with captive pictures of people in costume.  Your face lights up as you read that a traveling carnival is coming to town.  Smiling in anticipation of the music and games, you can’t wait to ask that beautiful girl from English class to be your date.  Rushing home to see how much money you have saved in your emergency tin under your mattress you sigh in relief realizing you should have just enough for a good time.

The traveling carnival finally makes it to town and almost everyone attends.  Despite the Depression, the lack of resources, the extreme poverty – people manage to round up a little bit of “extra” cash to experience a night of escape from the brutal realities of the era.  You arrive with your girl and go on some rides, enjoy some cotton candy and then make it to the games.  You are going to win something special for that English Class girl.  Playing the ring toss – the third time’s the charm – you finally earn that sought after prize.  Unlike the stuffed animals of today, you hand her a lovely glass bowl.  However, it is not just any glass bowl; it has a unique pattern and shine.  It flashes colors as you move it around in the light.

It was the same type of glass as that “Venetian Art” vase your mother cherished, yet now it had a new name: Carnival Glass.  Over those years this special iridized glass transformed as did the country; becoming a unique piece of American history whose own history correlates with the social changes of the time.

Carnival Glass dates back to the early 1900’s.  Back then it was not called Carnival Glass – it did not get coined with that term until much later.  So what exactly is carnival glass?  It is pressed glass with a pattern and is covered with an iridescent, metallic coating.  The two main aspects of Carnival Glass are the iridescence and the pattern.  These are the two characteristics that set Carnival Glass apart from other types of glass and individual pieces of carnival glass from one another.

 The first example of carnival-type glass was produced by Tiffany.  However, unlike the true Carnival Glass of today, the iridescence was infused in the glass itself, it was not a coating.  The fine glass became popular because of the way it played with light and seemed almost to glow.  However, this was an extremely expensive process.  In 1907 the Fenton Art Glass Company was the first company to produce another type of iridized glass which they termed Iridill.  They produced it to imitate the fine Tiffany glass, but because they applied the metallic iridescent coating on the already pressed glass, it was much cheaper to produce.   Fenton began to mass produce their Iridill and this is why you may hear Carnival Glass referred to as “poor man’s Tiffany.”

Soon after Fenton, other glass companies followed.  Another glass company Northwood, began to produce their own iridescent glass, “Golden Iris.”  This is the extremely popular marigold to which you will hear reference to again and again.  Another term you will hear referenced quite often in the world of Carnival Glass is Dugan.  Dugan was another company which produced iridescent glass soon after Northwood.  Their most distinguishing accomplishment is their opalescent iridized glass.

Millersburg was started by John Fenton while he was still president of the Fenton Company.  This company only produced glass for two years, but the quality of their pieces is extremely distinguished.  Finally the Imperial Glass Company was also a major producer of Carnival Glass.  Among these there are other companies which produced some carnival glass, but these are considered the main five.

Because of the industrial revolution, there is this massive production of iridescent glass from 1909 through the 20’s.  The glass is highly decorated and beautifully finished with the oily rainbow reflections.  It was popular and sold well at first, but by the late 1920’s interest began to wane.  Finally in 1929 the stock market crashed and the United States fell into the Great Depression.  Glass companies were stuck with loads of this iridized glass they could not sell to the public.  What they ended up doing was selling pieces in bulk to traveling carnivals which then used them widely as prizes for their games.  As the Depression worsened, carnivals grew in popularity and correspondingly in number.  Despite the tight financial situation of the population, the terrible daily conditions meant that people welcomed escape and these traveling carnivals offered the perfect solution.  They had distinctive games, stimulation for all your senses and they came rarely enough that it was worth the investment.

And so we see this product which reflects the ingenuity of man, the expansion of the industrial revolution and the result of mass fabrication come full circle to a humble end in the hands of a young girl, out one night at a carnival with a nice boy from her English class.  She treasures the beautiful glass with the unique shine as a special prize when such things are few and far between.  Today there exists an entire universe of “Carnival Glass Collection and Appreciation” populated by many people, of all ages, from all over.  Each day someone new stumbles upon this unique glass, either by happenstance or through research and find themselves wanting to know more and possibly even thinking to start their own collection.