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

Vintage items and thrifted products are gaining recognition for their appeal and popularity. Milk glass, known for its opaque colors and intricate designs, is making a comeback.

Milk glass achieves its opacity through the addition of various chemicals in the glass-making process. Titanium Dioxide, Zirconium Dioxide, and Cryolite are some examples. These chemicals are also commonly employed in other products for coloring purposes.

Understanding the glass production process helps differentiate authentic products from fakes. Glass is made by melting sand, soda ash, and limestone at high temperatures. Milk glass, on the other hand, incorporates chemicals like titanium dioxide, zirconium dioxide, or cryolite to achieve opacity.

How Glass Is Made

Various methods exist for making glass, but sand is the essential component. Manufacturers begin by heating sand to its melting point, typically at 1723 degrees Celsius or 3133.4 degrees Fahrenheit. Once melted, the sand transforms into a smooth liquid, ready to be molded into the desired shape.

To achieve the desired color, various methods are employed. One approach involves rolling or dipping melted sand into pre-colored crushed glass, blending them seamlessly. Alternatively, different chemicals can be added to alter the glass’s hue, ranging from white to brown, green, black, pink, and more. After forming the glass object, it’s placed in a specialized oven for thorough and proper cooling, preventing deformation or breakage over time. Once cooled, the captivating colors, design, and shape are firmly set, ready to be admired indefinitely.

Chemicals Used for Milk Glass Color/Opacity

Milk Glass, despite its name, doesn’t contain milk; instead, it’s crafted to achieve a smooth, milky-white appearance, hence the name. Various methods exist for tinting glass, tailored to the item’s purpose or desired aesthetic. To achieve the milky appearance, different chemicals can be introduced into the glass-making process, producing a range of colors and opacities in the final product.

Titanium Dioxide

Titanium dioxide serves as a coloring agent, renowned for its ability to produce an opaque, white hue. This white, odorless, and tasteless powder finds application not only in glassmaking but also in various other industries, including paints, paper, fabrics, cosmetics, sunscreen, food coloring, and more.

Zirconium Dioxide

Zirconium dioxide is another chemical utilized in tinting milk glass. Known for its heightened opacity, it is commonly employed in the production of tile, mirrors, sinks, and various other construction and building materials.

Cryolite

Cryolite, also known as sodium hexafluoroaluminate, is utilized to add opacity to glassware and enamel products. It’s also found in metals, insecticides, resin, rubber, and other applications.

Colored Milk Glass

While milk glass is commonly white, it’s also available in various other colors.

The renowned glass company Westmoreland produced not only white milk glass but also other hues like green and blue opal “milk” glass. Around 90% of their glass items maintained an opaque white appearance. In the 1950s, Westmoreland expanded its color palette to include amber, pink, brown, blue, and green milk glass. While they offered various shades of blue, only one distinct green glass color was produced.

The blue opal glass was crafted using powdered blue (dilute cobalt) and copper scales, whereas the green glass utilized iron scales. These scales were employed in three distinct formulas: two for blue glass and one for green glass.

“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’s blue opal glass ingredients included powdered blue (dilute cobalt) and copper scales, while the green opal glass utilized iron scales.

• 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)

Other popular milk glass colors comprise blue, pink, yellow, brown, black, and green, with blue being the most prevalent among them.

Colored milk glass can be produced by blending a mix of colors, resulting in what is known as “slag glass” or “marble glass,” which enjoyed peak popularity during the 1880s. This unique glass featured two colors swirled together to mimic the appearance of marble. Challinor, Taylor & Company of Pittsburgh was a notable producer of marble glass. (Source)

Identifying Authentic Milk Glass

Over time, companies have found cheaper methods and new chemical combinations to make milk glass. Some prefer the original formulas, considering the newer versions less authentic. Original milk glass products are now rare and harder to find among cheaper alternatives.

Newer methods of making milk glass are gaining popularity and accessibility among everyday consumers. This benefits manufacturers financially and doesn’t diminish the authenticity of the products. Nowadays, many people prefer the vintage look without the high cost or effort of finding original pieces.

Several products closely resemble milk glass and can be challenging to differentiate. If you’re not particular about the manufacturing process and simply appreciate the appearance, feel free to choose what appeals to you. However, if you’re seeking authentic milk glass, it’s crucial to know how to distinguish it from similar items.

Markings and Manufacturer Initials

Glass companies typically mark or “sign” their work with their initials or names, akin to artists signing their creations. This practice aids buyers in identifying authentic pieces and promotes brand recognition to attract more customers. Two prominent milk glass manufacturers are Fenton Glass and Westmoreland Glass.

Platonite glass, often mistaken for milk glass, emerged in 1936. It features an opaque base adorned with a fired-on finish or design for a distinct appearance. This glass was patented by the Hazel Atlas Glass Company. To distinguish their products, inspect the bottom of the item; most, if not all, pieces will bear markings such as “HA” or “PLATONITE.”

History of Milk Glass

Milk glass gained prominence in Venice during the sixteenth century, esteemed for its high quality, luxury, and expense. As its popularity grew and demand increased, glass manufacturers in the 19th century developed methods to create more affordable versions accessible to the average American. This allowed milk glass to compete with porcelain, crystal, and expensive China. Over time, additional colors like blue, purple, black, gray, and pink were introduced to the milk glass family, expanding beyond the original opaque white. (Source)

Homemade Milk Glass

In contemporary interior design, there’s a trend towards recreating the aesthetic of authentic vintage pieces rather than investing heavily in original items. Making homemade milk glass offers a cost-effective approach to achieving this look while allowing for personalization and creativity in home decoration.

Begin your homemade milk glass project by browsing local thrift stores or similar venues for suitable vessels such as vases, jars, or decorative pieces. Focus on the design and details rather than the color of the item. Once you’ve selected one, take it home and clean it thoroughly. Start by washing with soap and warm water to remove dust, dirt, and oil. Then, use a cotton pad soaked in rubbing alcohol to gently clean the entire outer surface, ensuring any oils or substances are removed. Allow the item to dry for several minutes before proceeding.

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

Paint

Whether your item is clear or colored, you can use this method to transform it. Choose the paint color you prefer, ensuring it’s suitable for glass. Spray paint is quicker and avoids brush strokes.

Once you’ve chosen the color and paint method, apply thin layers of paint, letting each coat dry completely. Build opacity and smoothness with multiple coats. Finish by sealing with clear acrylic paint for protection against chipping and water damage.

Textured Surface

If your item has a flat surface, you can replicate the Fenton hobnail design. Clean it, then use flatback craft studs or pearls and superglue to create the pattern.

Once the studs have dried, proceed to paint with your chosen color. Using spray paint makes it easier to avoid disturbing the studs. Apply multiple coats, with drying time in between. Optionally, apply a paint sealant for protection.

Another approach to achieving the Fenton hobnail design is by using a hot glue gun to create the raised dots. This method is cost-effective and has a faster drying time. However, achieving symmetry with equal-sized dots can be challenging, and hot glue may not adhere well to glass. Apply multiple paint layers afterward and seal with a paint sealer for protection.

Individual preferences influence choices in acquiring or creating milk glass for home decor. Fortunately, a variety of products, brands, alternatives, and project ideas are available to achieve similar appearances to these popular opaque items.