The idea of insertions in stained glass windows is simple. Create a hole in a piece of glass and insert another piece of glass (probably of a different colour) that has been shaped to fit the hole. In practice of course this required a great deal of skill. Silica or a copper wheel embedded with abrasives was used to grind a hole through a piece of glass. Another piece of glass would then be cut precisely to fit into the hole and wrapped in a thin lead came. This was then carefully inserted into the hole in the larger piece of glass. Once in place the lead would be soldered to hold the new insertion in position.
The Burrell Collection has many superb examples of the insertion technique on display. Mostly it is found in heraldic glass, probably as a display of wealth, as only the most highly skilled glaziers used these techniques, and it would have been expensive! One of the finest examples you are likely to see is the Tudor rose panel in the Hutton hall.
This is a roundel with the red and white rose of Lancaster and York on a purple background between two green leaves with a red border. It is English and dates to the 16th century. It is possible that it was originally placed in a shield. This is a particularly unique example as it has four layers of insertions altogether in one piece. It is extremely rare to see so many insertions within insertions. This would have taken a lot of time, patience and skill to make!
Other fine examples can be seen in the heraldic panels from Fawsley Hall, for example the Shield of Thomas Harrowdon and the Shield of Sir Richard Knightley and Elizabeth Purefoy. These panels were part of a large series of heraldry commissioned by Sir Edmund Knightley to illustrate his family history and his links to royalty. Edmund was knighted by Henry VIII and made commissioner for the Suppression of the Monasteries, the wealth associated with such a powerful position enabled him to commission the finest glaziers at the time to create these windows using the most highly skilled techniques.
In the shield of Thomas Harrowdon the detail on the left is taken with reflected light and on the right, transmitted light. Notice the little circle where the red flashing has been ground away inside the insertion to create a small crescent. In the Shield of Sir Richard Knightley and Elizabeth Purefoy:
You can see several insertions in this panel: The 6 triangular shapes like the two detailed and the stag’s head with a blue insertion between the antlers. Because of the unusual shapes and the narrow width of glass used, these pieces would have been at a high risk of breaking, so the fact that they have survived for nearly 500 years is absolutely remarkable!