Gold Coating a Casio Watch by Vacuum Evaporation | Periodic Videos

Summary

In this Periodic Videos episode, the team attempts to gold-plate a cheap Casio watch using a specialized evaporator in a high vacuum. The video blends hands-on lab technique with explanations of gold's unusual chemistry and its long history, from natural gold deposits to Faraday colloids and modern catalysis. The process illustrates thin-film deposition at nanometer-scale thickness and highlights the interplay between materials science and historical context.

• Thin-film gold coating produced by vacuum deposition deposits a nanometer-scale layer on the watch.
• High vacuum conditions and current between electrodes drive gold evaporation and deposition onto the surface.
• Observation of gold films on the watch and chamber windows demonstrates deposition patterns and practical lab considerations.
• Gold's inertness, bonding, and historical significance are discussed alongside early alchemy and modern catalysis contexts.

Introduction and goal

This Periodic Videos segment follows Brady and Neil as they attempt to gold-coat a cheap Casio watch. The plan uses a custom evaporation setup housed in a vacuum chamber to heat and vaporize gold, which will then condense onto the watch, forming a very thin, nanometer-scale film that gives the surface a gold appearance.

Gold in nature and history

The narration covers gold's unique status as a metal that can be found naturally in native lumps and its historical allure. It also touches on the broader context of gold in science and industry, including Faraday’s early demonstrations of gold in colloidal form and later uses of gold as a catalyst in chemical reactions.

Vacuum evaporation setup and procedure

Before placing the watch in the turbo-pump vacuum system, a test is performed in a non-turbo chamber to avoid damaging equipment. The team then increases the current to heat the gold-coated bolt until evaporation begins. The process is conducted under extreme vacuum, with pressures around 0.1 millibar, to ensure a clean, uniform deposition without oxidation or contamination.

Observation and deposition

As gold evaporates from a small boat, atoms travel to the watch and walls of the chamber. The film forms on the outside of the watch and on the chamber windows, with gaps where the watch holder or bars block deposition. The video explains the optical effects of thin films, noting that a few atomic layers suffice to create a shiny appearance due to delocalized electrons.

Analysis and context

The discussion places the experiment in a broader scientific and historical framework, connecting laboratory practice with gold’s reactive and catalytic behavior, the alchemist’s dream of turning cheap metals into gold, and Newton’s ties to alchemy. The host notes practical concerns, such as safety and the fact that even a small amount of gold can visibly alter the watch, while also reflecting on mercury interactions that can affect jewelry.

Conclusion

The front of the watch ends up coated with a gold film, though the deposition is not perfectly uniform. The video emphasizes that the result is a thin, superficial layer rather than a solid gold piece, illustrating the power and limits of thin-film deposition in real-world lab settings.