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Artifact of the Month: Glass

Conservator Terry introduces glass, an artifact type found in abundance on QAR

Author: Terry Williams, Conservator

Manufacturing glass
Methods of glass production

Did you know that people have been using glass for millennia? The first glass used was obsidian, a volcanic product which is formed when magma suddenly cools. Obsidian was used to make weapons and tools such as knives and projectile points, in creating jewelry and even served as money. According to archaeological evidence, the first man-made glass was made in Eastern Mesopotamia (modern day Middle East) and Egypt in 3500 BC. In the very early days, it was quite the challenge to make glass: furnaces were small, and the heat they generated was barely enough to melt glass. Then, in the 1st century BC, Syrian craftsmen invented the blow pipe. Glass manufacturing eventually developed in Venice and spread through Northern Europe. The blow pipe method of glass production can still be seen today, for example at amusement parks and in art programs in universities.

Glass blowing continued to be the main method for making glass until the 1820s when parts of the process became mechanized. By the 1890s, glass usage and manufacture greatly expanded, eventually becoming the process used today.

Case bottle base
Base of case bottle

You may remember, x-rays are used to identify objects in concretion. Unfortunately, this means that unless glass is made with lead, it is not visible when viewing a concretion’s x-ray. Fortunately for us, glass is often found exposed, or on the exterior of a concretion. You may also remember that concretion is generally formed around iron objects; therefore, if the glass is buried in concretion, it is because it got caught during the development of the concretion.

Glass from our site includes wine and case bottles, wine glasses, beads, and window glass. Case bottles get their name from the wooden shipping containers used to transport them. Glass for windows is a type called “crown” glass. The irregularity in the middle is where the glass was detached from the rod by a sharp blow during its manufacture. This is called a pontil scar and can be used to date glass.

Pane of glass with pontil scar
Glass with pontil scar

Glass is generally fragile and can easily shatter into hundreds of pieces after an inconvenient drop. However, the glass itself is often resilient, keeping much of its original appearance if not function. This holds true for our glass as well, an amazing feat when you consider how much glass is found on the wreck, a salty, abrasive site that is over 300 years old!

Check back as we further explore specific types of glass found on the site!

Suggested Reading:
Carnes-McNaughton, L. and M. U. Wilde-Ramsing. 2008. Preliminary Glassware and Bottle Analysis from Shipwreck 31CR314, Queen Anne’s Revenge Site. QAR Research Report and Bulletin Series QAR-R-08-02. Manuscript, QAR Conservation Lab, Greenville, NC.

The several methods of blowing and casting plate glass with the men at work, from Universal Magazine, 1747. Library of Congress. {{PD-old-100}}
Base of case bottle from site 31CR314. Image by NC Department of Natural and Cultural Resources.
Glass with pontil scar from site 31CR314. Image by NC Department of Natural and Cultural Resources.


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