“Ta-ke” cooper model rain chain after 4 years since installment


Copper is resistant to corrosion even when used outdoors and has been used for roofing and exterior materials since the past in Japan. Copper is an expensive metal compared to iron, but it is soft and easy to process, and due to these features, cooper is an established material that has been used in Japan since the Edo period (1603-1868CE).


The reason why copper has such a strong corrosion resistance despite being a relatively soft material among metals is because it protects the inner copper by forming a green film called “Patina” on its surface. Many of the Buddha statues and monuments placed outdoors are made of copper alloy, and some are covered with green color. It is not a painted color, but it has a film of patina on the surface. The Statue of Liberty in New York has also become green color, but it is not from any color paint. The green color is from the patina generated by exposure to wind and rain, a thin film that protects its body, allowing it to endure many years of existence outdoors without degrading aesthetics.


So what is patina? It is a compound resulting from oxygen, carbon dioxide, moisture and salt in the air. An oxide film is a type of compound, which is generally called “rust”, and if you leave an iron plate outdoors without any protective coating, a familiar red rust will appear, and the iron plate will be corroded over the years. Red rust is a chemical change to iron oxide from the combination of iron and oxygen in the air, and when copper is exposed to the air, it also reacts with oxygen, water, carbon dioxide, and salt to produce patina. Patina takes a while to appear, but the naturally generated green color due to aging is not uniform and has a deep and unique beauty that cannot be artificially produced.


A house situated in Toyama Prefecture is observing secular change on its hanging “Ta-ke” model rain chain. The photo is shown at the Top, and it has been about 4 years since it was installed, and I will be posting the progress on a regular basis to show how the patina gradually becomes darker and its changes from year to year.


At SEO Inc., we offer cooper rain chains purposely without clear coatings, including Ta-ke, Ajiro and Toh models. Please enjoy the secular changes on the cooper rain chain at your own home or building.



 1st day of installation


6 months after installation


2 years after installation