Milk Glass: How Is It Made and What Makes It Opaque?

Today, vintage items and thrifted products are being recognized as more beautiful, valuable, and popular in many homes. One of these items that is coming back into the light is milk glass. It’s known for its unique opaque colors, smooth surfaces, and detailed designs.

Milk Glass is made by adding different chemicals into the glass-making process that creates the opacity of milk glass. Some chemicals that can be used to do this are Titanium Dioxide, Zirconium Dioxide, and Cryolite. These chemicals are also used in other products for coloring purposes.

Understanding just how glass products are made can be helpful in finding real, authentic products instead of knockoffs or fakes. So exactly how is glass made in the first place, and how is milk glass made differently?

By hottholler - Blue Room - Milk Glass Collection- 25 pieces of White Milk Glass, Hobnail, bowls, pitchers.

Understanding How Glass Is Made

There are different methods for making glass, but the most common denominator and “ingredient” for making glass is sand. Manufacturers will start by heating sand to its melting point, which is 1723 degrees Celsius, or 3133.4 degrees Fahrenheit. Once the sand has melted, it will become a smooth liquid, which is then able to be manipulated and shaped into the desired product. (Source)

To add color, there are several different methods for achieving the desired look. One way that is used is the melted sand can be rolled or dipped into pre-colored crushed glass that melts in with the rest of the roll. Or, different chemicals can be added that will change the color of the glass, depending on the color, whether it be white, brown, green, black, pink, and so on. Once the glass object has been formed, it’s placed in a special kind of oven that allows the glass to cool thoroughly and properly to prevent it from moving or breaking over time. Once it has cooled correctly, the beautiful and unique colors, design, and shape will be set in place and can be admired forever.

Chemicals Used for Milk Glass Color/Opacity

Milk Glass, contrary to its name, is not created with milk, but rather it is made to have a smooth, milky-white color, hence the name. There are so many different ways to make colored or tinted glass, depending on the item’s purpose or the desired look of the glass. To meet the desired milky look, several different chemicals can be included and added into the glass-making process to create different colors and opacities of the end product.

Titanium Dioxide

One chemical that is used for its coloring abilities is Titanium Dioxide. It is a white, odorless, and tasteless powder that can be used to create an opaque, white color. Titanium Dioxide is also used in other products such as paints, paper, fabrics, cosmetics, sunscreen, food coloring, and so on.

Zirconium Dioxide

Another chemical used for adding color to milk glass is Zirconium Dioxide. This chemical has a higher opacity and is often used in the making of tile, mirrors, sinks, and other construction or building products.

Cryolite

Cryolite, also technically known as Sodium Hexafluoroaluminate, is found as an odorless white powder or solid. It’s used for adding opacity to glassware and enamel products, and it is often found in metals, insecticides, resin, rubber, and other products.

Milk Glass Pitcher and Drinking Glasses
Milk Glass Pitcher and Drinking Glasses

Colored Milk Glass

Milk glass, although typically white in color, can also be found in a multitude of other colors.

A famous milk class company, Westmoreland, created not only white milk glass but other colors as well, such as green and blue opal “milk” glass. Most of their milk glass products lived up to the name with around 90% of their glass displaying the opaque white hue. Later on in the company’s time, in the 1950s, Westmoreland also created products in new colors such as amber, pink, brown, blue, and green milk glass. Although they created many different shades of blue glass, there was only one distinct green glass color. (Source)

The blue opal glass was made with powdered blue (dilute cobalt) and copper scales, but the green glass used iron scales. The scales were found in three formulas: two blue formulas and one green formula.

“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!”

Source

Westmoreland blue and green opal glass ingredients:

  • Mostly sand
  • Soda ash
  • Lime
  • Potash
  • Saltpeter
  • Lead
  • Fluor and Feldspar
  • Dilute Cobalt (in the blue glass)
  • Copper Scales (in the blue glass)
  • Iron Scales (in the green glass)
    Source

Other common and popular milk glass colors include blue, pink, yellow, brown, black, and green, although blue is the most common colored milk glass.

Colored milk glass can also be created by combining a mixture of colors. This unique glass is called “slag glass” or “marble glass” and was most popular during the 1880s. Two colors of glass were swirled together to create glass that looked like marble. A common creator of marble glass was Challinor, Taylor & Company of Pittsburgh. (Source)

Check out our full article for more information on distinguishing between different types of milk glass.

Identifying Authentic Milk Glass

Over time, manufacturing companies have discovered new and less expensive methods, as well as chemical combinations, to create milk glass. There may be some people who value the original formulas of milk glass products more, and who may consider the newer versions cheap or inauthentic compared to what they used to be. It is much harder to find these original makes of milk glass products amongst the multitude of inexpensive products. They are less common and are typically no longer made.

The newer versions and methods of making milk glass are now more popular and accessible for the everyday person, which in turn, puts more money in the manufacturers’ companies, and they are not considered inauthentic products. Most people nowadays just want the same look of the vintage pieces without having to pay such a high price or search high and low for the originals.

Many different products are very similar to milk glass and can be hard to tell apart. Of course, if you are not necessarily picky on exactly how the product is made and just enjoy the look of the item, go ahead and just pick out what you like! But if you are looking for those true milk glass products, knowing how to pick them out amongst their look-alikes is important.

Markings and Manufacturer Initials

Every glass company and manufacturer is an artist of their own kind, and like other artists, they mark or “sign” their work with the company’s initials or name. This helps buyers to determine authentic pieces, and also to make their company name known to gain more customers. Two of the most common and popular milk glass manufacturers today are Fenton Glass and Westmoreland Glass.

A product that is commonly confused with milk glass is platonite glass. Created in 1936, platonite glass is made with an opaque base and is then topped with a fired-on finish or design to create a unique look. This glass was patented by a company called Hazel Atlas Glass Company. To identify their products, look at the bottom of the item. Most, if not all, of their pieces will be marked on the bottoms with “HA”, or “PLATONITE”.

Learn more about valuing your milk glass.

History of Milk Glass

Milk glass was first popular in Venice during the Sixteenth Century. Anything made from milk glass was seen as high-quality, luxurious, and expensive. Over time, as it became more popular and more people wanted to purchase its products, glass manufacturing companies in the Nineteenth Century made their own way of creating milk glass that would give the same beautiful look but would be more accessible for the average American as opposed to other products made from porcelain, crystal, or expensive China. Eventually, more colors were added into the Milk Glass family, including blue, purple, black, gray, pink, etc., in addition to the original opaque white. (source)

Check out our full article on the history of milk glass for more information.

Homemade Milk Glass

When styling and designing the interior of a space, most people these days are focusing more on achieving a similar look to replicate original authentic pieces rather than splurging and spending large amounts of money to make sure they can have those older vintage items. Creating your own homemade milk glass not only helps to stretch a dollar, but it can also be a more personalized and creative way to decorate the home.

Start by searching through your local thrift store or anywhere else that sells the kind of vessel or item you are looking to create with, such as a vase, jar, decorative piece, etc. Do not focus on the color of the item as is. Pay attention to the design and details. Once you find one you like, take it home to clean. To do this, start by cleaning with soap and warm water to remove dust, dirt, and oil that may be covering the surface. Next, use a cotton pad and rubbing alcohol to gently clean the entire outer surface, and allow it to dry for several minutes. The rubbing alcohol will ensure you have removed any oils or substances that could interfere with the paint gripping to the item properly.

Next, you will want to decide what kind of design you are looking to create.

Paint

Whether you have an item that is clear or colored, you can use this method to transform it. You will first want to select the color of paint you’d like your newfound piece to be. As previously mentioned, most milk glass items are white, but some are pink, light blue, light green, gray, black, etc. The beauty of this project is that you can use whatever color you think will best suit your space! You will also want to decide if you would like to use spray paint or brush-on paint. Spray paint will probably be the easiest method because it applies much quicker, and there will be no brush strokes or lines to worry about. Be sure to check and make sure the paint you purchase was made to be applied onto glass.

Once you have selected a color and paint method, apply a thin layer of paint all around the outside of the item. Give it an hour or so to dry completely. Next, apply a second, then a third coat of paint to build the opacity and smooth the texture. You can also finish it off by applying a thin layer of a clear acrylic paint sealant to protect it from chipping and water damage. (Source)

Textured Surface

If you purchased an item that has a flat, smooth surface, you have the option to replicate the popular Fenton hobnail design. The hobnail is a design of a vessel with a pattern of raised dots on the surface. There are two methods to recreate this design. First, after cleaning and wiping your piece with alcohol, you can purchase a package of flatback craft studs or pearls. Using superglue, carefully glue each stud or pearl in the Fenton pattern or in a pattern of your own choosing.

Fenton Hobnail Milk Glass
Fenton Hobnail Milk Glass

Once they have dried thoroughly for several hours, go ahead and spray paint or brush paint the color of your choosing. Using spray paint will be much easier for this method so as not to disturb the studs’ positions. Apply several coats with plenty of drying time in between, and apply an optional paint sealant to protect your end project.

The second option to achieve the Fenton hobnail design is by using a hot glue gun to form the exterior raised dots. This is a cheaper method with a faster drying time. However, creating a symmetrical pattern with equal-sized dots is much more difficult to accomplish with hot glue. Hot glue also doesn’t hold as well to most materials, including glass, so the dots may chip or fall off over time. Nonetheless, if you choose to use a hot glue gun to create the hobnail look, apply several layers of paint afterward and protect with a paint sealer.

Everyone has their preferences in what they choose to purchase or create for their home. Whatever way you like your milk glass, there are many products, brands, dupes, and project ideas to achieve a very similar, if not identical appearance to those beautiful opaque vessels and items that are so popular!

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