What is Milk Glass?

Milk glass has a fascinating and quite toxic history. It has its roots in the 16th century, but only really had an impact when it was the choice colour for tableware and trinkets in the early 19th century. These are the pieces we can collect today.

The definition of milk glass is “semi-translucent glass, whitened by the addition of various ingredients”. Once you have the opaque glass in the milk colour, it can then be pressed into a mould or hand-blown. The hand-blown types are more valuable due to the skill and work it takes to produce. Strangely, milk glass can also come in other colours, including blue, pink, yellow, brown and black.

This beautiful milk glass bowl is typical of the serving pieces of the late 19th century.

Why was it made?

In the early days of porcelain manufacture in Europe, the highly sought-after shiny white products were so expensive they were often called white gold. For many years, from 1707, the true white porcelain that originated in China was made in one factory, Meissen, which was located in Saxony (south-eastern Germany). In Venice in the 16th Century, glass blowing had already been around since the early 1200s when the Venetian Glassmakers’ Guild was formed. In 1291, all the glassmakers in Venice were forced to move to the island of Murano, and the designs and magnificent pieces we see are often from this island.

The invention of milk glass, which the Venetians called ‘Lattimo’, was to make a more cost-effective look-alike to porcelain. Beautifully decorated Lattimo glass became the rage for nearly three centuries. Lattimo translates to milk white in English, but it wasn’t until the 1930s that the name milk glass or opal glass became popular.

How milk glass is made

The glass makers of Murano experimented for years to develop the perfect milk glass recipe, which is both translucent and opaque. The initial chemical they added to make the glass cloudy was arsenic (my toxic heading for this article). Later, they experimented with crystal amalgam, manganese oxide for bleaching, and tin oxide to make it cloudy and matte. In the early days, lead arsenic was used instead of tin oxide, but it was discarded due to its toxicity. Today, the matting agent they use is mostly calcium fluoride and others, on the more harmless side, like bone ash, amongst other chemicals.

Collectors

Many things in the glass industry were made from milk glass, including dinnerware and tableware, lamp bases, vases, trinket boxes, wedding baskets, decorative baskets and containers, jewellery, and more. Glass panels and signage in the early 1900s included some milk glass. One of my favourites is the milk glass hobnail patterns, many made by the American Fenton Art Glass Company in the 1930s and very collectable. The companies that made and still make milk glass have a range of styles and items that make them unique. The fun part for collectors is learning about all the styles and making a collection you love. Milk glass can be displayed in all different styles and eras together to make a cohesive look.

A wine-shaped goblet in milk glass with a clear glass stem perfect for displaying flowers.

How to identify milk glass

Vintage milk glass is bright white and opaque. When held up to light, it will be iridescent. Many of the items you find will not have the maker's mark. In general, the more valuable items are the ones that look well-made. If it looks cheap, it probably is. As an example, the Fenton hobnail pattern is neat and sharp, whereas knockoffs are often rounded and not identically placed.

If the glass does have the manufacturer’s mark, make sure it matches the company marks – these have also been known to be faked.

There are a few things to note:

• You cannot see through milk glass – it should be a solid, creamy white colour.

• Milk glass is not made into plates and dishes, but more serving dishes and decorative pieces.

• Seams indicate that the moulded piece may be older, but they are never in the middle of a pattern.

• Make sure the colour is not painted on plain glass. Milk glass has the colour within. This is easy enough to see when looking at the piece.

• Older milk glass, when held up to the light, will have what is called a ring of fire or halo effect. This will more likely be milk glass produced before the 1960s. Milk glass after this can still be valuable, though.

• Moulded milk glass with patterns on the outside is usually not sharp, but has the same rounded feel as other pressed glass pieces. Cut glass should be sharper, as would cut crystal.

• Some milk glass is identifiable by the pattern, such as the hobnail pattern. Others include grape patterns and beaded edges of Westmoreland Glass (USA), or the animal designs by Atterbury & Company (USA).

• Hand-blown glass often can be distinguished from mass-produced or moulded glass by the evidence of the pontil mark on the base. This is where the metal rod was positioned when blowing the glass, leaving a round scar on the base when removed.

The manufacturer's websites provide a lot of information, and if you are still unsure, ask an expert for a decent valuation.

I find milk glass fascinating mainly because it's not your usual glassware, and the vintage items are truly works of art. Look out for these at thrift stores and vintage markets.