Patina is the way a watch ages, so that its look, and usually its colour, changes over time. It comes from long exposure to sunlight, hot and humid climates, or simply the passing of time. It matters because watches with strong colouring or a distinctive aged feature sell for higher prices.
What makes a watch develop patina?
The pace of change depends on several things. Ultraviolet light is one. Humidity and oxygen are others. Swings in temperature play a part, and so does how long the watch is worn. Patina is not limited to dials and hands. Bronze cases darken from gold to brown, and copper salts can turn them green or blue.
How does lume change colour?
Watchmakers first made hands and hour markers glow in the dark with radium, a radioactive material. In the 1950s they largely moved to tritium. Tritium lume that ages well darkens in stages. It starts white, turns cream, then orange, then chocolate brown. On vintage Rolex watches, the lume plots lost their crisp edges over time and turned cream or a dull yellow.
What is a tropical dial?
A tropical dial is a faded, discoloured dial found on some vintage sports watches. The paint has lost its first colour and taken on another. Collectors value these dials highly. The change can be slow. Old dial paint can take 20 to 40 years to fade to the warm brown of a tropical dial.
Not to be confused with
Patina is not damage. Damage includes moisture stains, spots on the dial, mould and heavy corrosion. Lume that has broken down counts as damage too, not as patina. Fake patina is another trap. It is made with chemicals or forced exposure. It tends to look too even, or to change too suddenly.
Checked