A Tale of Two Knobs: The Curious Case of Solarized Glass
- Charleston Hardware Co.
- Aug 8, 2024
- 1 min read
Antique glass knobs crafted between the mid -19th and early 20th centuries hold a fascinating secret. These seemingly ordinary pieces of hardware often concealed a surprising transformation. To achieve the coveted crystal clarity, glassmakers of the era incorporated manganese dioxide into the molten glass. However, this additive possessed an unexpected characteristic: over time, when exposed to sunlight, the glass would develop a captivating purple hue, a phenomenon known as solarization.
It’s a quirk of history that has delighted and puzzled collectors for generations. We often encounter customers who present a curious pair: one knob clear as crystal, the other bathed in a mysterious purple glow. This subtle color disparity offers a intriguing clue to the knob’s history: the clear knob likely adorned an interior hallway shielded from sunlight, while its counterpart basked in the radiant embrace of a sunny room.
Interestingly, modern glass knobs are immune to this enchanting transformation. While advancements in glassmaking technology undoubtedly play a role, the real turning point came during World War I when manganese was diverted for munitions production. As a result, the practice of using manganese dioxide as a decolorizer was curtailed, marking the end of this captivating chapter in glassmaking history.
How's that for a fun fact?
Antique glass knobs from the mid-19th to early 20th centuries captivate collectors with their intriguing solarization effect, where exposure to sunlight transforms clear glass into a stunning purple hue. This historical quirk often leads to fascinating discoveries about the placement and use of these knobs. Local locksmiths frequently encounter such pieces while restoring vintage hardware, marveling at their unique charm and the craftsmanship of bygone eras. The transition from manganese use during World War I marked the end of this enchanting glassmaking chapter.