Working with stained glass can create remarkable and ever-changing effects that are impossible through the use of wraps, posters or conventional paint.
Because it inherently interacts with light in a much more unique and deeper respect than other materials, stained glass has an inherent connection to time and place. This is often why a glass frontage or display has a tendency to look almost alive, interacting with its location.
Taking this into account is what creates such astonishing results, such as the almost ethereal glow that many medieval stained glass portraits have whilst in situ.
However, even before the history of stained glass windows as we know them, this principle had already been established by early masters of glassblowing, and one of the best examples of this is seen in the Lycurgus Cup.
The only complete example of Roman dichroic glass, the Lycurgus cup depicted the mythical King’s attempt to kill Bacchus’ acolyte Ambrosia through the medium of metal engravings on what is considered today to be a cage cup.
What makes it so unique and prized today is just how stark the difference is between the two different colours the glass turns into. When the glass is lit from behind, it appears a vivid, deep red, whilst from the front, the light bounces off of it, leaving an opaque green.
Whilst dichroic glass has been achieved in stained glass through other means, it took until the 1990s for the secrets behind the Lycurgus cup’s colour-changing effect to become apparent.
The secret to how it worked involved tiny fragments of silver and gold dust that might have been included throughout the glass material through accidental contamination.
The levels of gold and silver that were found were only discovered through the use of an electron microscope, and as it is believed that the Roman artisans could not have done this deliberately, it was likely made by adding gold or silver leaf and then diluting the mixture with more glass.