Bronze Watch Experiment #2: Plant Fertilizer
Here's a follow-up in my bronze watch experimentation series. I added a coat of greenish patina using 20-20-20 plant fertilizer. With the tough dark brown gun blue patina already in place, it took 24 hours to get this far. I made a super thick mixture of fertilizer and water and applied it repeatedly. The green is not yet distinct, and also pretty soft. I'll plan let it rest a few days and try again.
New leather band: green ostrich...yow...!
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Vlad the Inhaler
Watch for falling rocks all along the watchtower.
Member since
Last active: 2 weeks ago
Well I guess I've seen everything now.
That's not patina, that's corrosion...
To each his own, but why not just let it patina naturally?
That's not patina, that's corrosion...
To each his own, but why not just let it patina naturally?
Metal patina = corrosion.
I started this project because I found a wide range of naive commentary about expectations for the final appearance of bronze watches, and also limited awareness of how to create patinas. This is despite decades and centuries of metal finishing science and artistic experience. Watch hobbyists today don't seem to interact much with the arts and crafts crowd. Wearing a watch will expose it to sweat and salts, and this sends it down a predictable patina path based on how body chemicals interact with a specific bronze alloy. For example, CuSN8 bronze easily turns dark brown while aluminum bronze alloys (e.g., Tudor's current products) will remain much more yellowish.
A natural patina is often (1) very slow and smelly, (2) predictable, (3) disappointing to some when it results in a plain dingy/tarnished appearance, and (4) can continue past a desired end point. In contrast, a forced patina uses the established chemistry to rapidly reach a predictable and controlled outcome. If desired any patina can be coated to preserve the appearance (later experiments planned on my end).
I bought this watch to experiment, not to wait for some magical and personal patina to occur. I've been there and done that. Most of the time the outcome is plain and boring.
A reviewer who was disappointed and unhappy with a typical natural bronze patina:
https://www.youtube.com/watch?v=mUE9zs6KMBM
Examples of naive and clumsy forced watch patinas (these are NOT fully reversible):
https://deployant.com/the-bronzed-patina-the-curious-case-of-patina-how-to-get-it-and-how-not-to/
https://www.youtube.com/watch?v=P2ixqbnuGoU
Examples of the informed chemistry of patinas, even down to interactions with specific alloys:
https://exarc.net/issue-2017-2/ea/colour-palette-antique-bronzes-experimental-archaeology-project
https://www.sciencecompany.com/Patina-Formulas-for-Brass-Bronze-and-Copper.aspx