Vintage laboratory glass has been widely used by top decorators in recent years to highlight vintage industrial themed interiors.

But what most readers can’t tell from those glamorous double page magazine spreads is what makes one piece of laboratory glass shoe leather common and another a jewel. In this article, I’ll discuss the features experienced collectors and decorators use when evaluating these unique pieces.

But first, just what is laboratory glassware? Laboratory glassware, as the name implies, encompasses all the specialized shapes and sizes of utilitarian glass vessels typically used in a medical, educational, research or any specialized industrial production facility. Due to its highly specialized nature, laboratory glassware has always been made on a very limited scale compared to household, institutional and commercial beverage and kitchen glassware. A sampling of four pieces of vintage laboratory glass appears in Fig. 1.

So how can you tell it’s vintage? There are several easy ways to arrive at an approximate date of production. First, look at how the markings, called graduations, are applied. Most mass produced pieces made since around WWII have graduations that appear to be printed in white paint or ink on the glass surface or the graduations are molded in the glass (Fig. 4). Older, more desirable laboratory glass has ground or etched graduations (Fig. 2).

Fig 2.

Most ground graduations are called “wheel engraved” because they were made by holding the edge of a small wheel (usually copper) at right angles to the glass surface. Wheel engraved graduations are relatively simple and may appear somewhat crude. Copper wheel engraving on laboratory glass dates from the mid 19th century to around the 1920s in most American-made products.

The alternative way of making thinner and finer graduations was to use a diamond tipped stylus which resembles a wood pencil with an industrial diamond for a tip. The company name that appears in an almost cursive handwritten style in Fig. 3, for example, was created with diamond engraving. Diamond engraved graduations are generally found on the very best laboratory glassware and usually date from late 19th century to the 1930s.

Fig. 3

Another feature which enhances the value of laboratory glassware is one or more layers of colored glass. Colored glass was generally added for a very specific purpose such as making certain chemicals more visible or as an instant arms-length visual reference to indicate a certain volume had been reached. While all applied colored glass is highly desirable, cobalt blue and green are found the least. Virtually all laboratory glassware with any applied colored layers is scarcer than its single clear glass cousins. The more surface area the colored glass covers, the more desirable the piece.

Fig 4

Pieces marked with American place names and American glass makers are also more highly valued by collectors in the USA. And you don’t have to be an expert in early scientific instrument or glass makers to recognize these pieces. “Pyrex,” for example, was patented in 1915 and has been mass produced for decades and it’s a rare hermit or alien being that wouldn’t recognize that name. As a general rule, if you’re a general line antiques dealer or casual collector, any name YOU recognize on a piece of laboratory glass is probably NOT an early or exclusive maker.

Another good sign of quality, but not necessarily age, is a ground glass mouth with matching ground glass stopper. Stoppers were ground to fit specific mouths and required extra skilled hand work. Grinding produced liquid tight and air tight seals. A stopper is with its original flask if it sits evenly in the mouth and you can feel it “seal” with just a slight twist.

Besides being used to contrast with and accent heavy wood and metal industrial pieces, many collectors like using their laboratory pieces as bar ware. The large flared beakers with pour spout like the piece second from left in Fig. 1, for example, are highly favored as martini pitchers.

CAPTIONS

Fig. 1  Group of vintage laboratory glassware. Left to right: 10 inch flask, engraved graduations on applied cobalt glass stripe; 11 inch martini pitcher-size beaker with wheel engraved graduations; 10 inch beaker with pour spout, engraved graduations on applied ruby glass stripe; 13½ inch flask with applied ruby glass volume guide.

Fig. 2  Engraved markings and graduations are a sign of authentic age and highly skilled assembly. Top: diamond tipped stylus or “pencil” graduations. Below: Wheel engraved graduations applied by holding edge of grinding wheel at right angle to glass surface.

Fig. 3  Top: Diamond tip engraved company name “Richards Ltd, New York-Chicago” on laboratory flask at far left in Fig. 1. Below: Detail view of ground glass mouth with matching ground glass stopper.

Fig. 4 Typical flat white printed lettering, left, and molded raised lettering, right, associated with mass produced laboratory glass since about 1940. However, some molded Pyrex marks may be earlier.

Wrtten by Mark Chervenka