Hello, everyone!
I’m Andy, a tea enthusiast.
There are various types of metal cans, and they are among the best containers for storing tea.
They are durable and lightweight, making them highly convenient.
This time, instead of discussing the materials, I will focus on the forming methods of metal cans and how each type is used for storing tea.
Metal cans can be categorized into clinched cans (also known as crimped or interlocked cans), welded cans, and seamless (one-piece) cans based on their forming methods.
When storing tea, airtightness and light-blocking ability are key factors.
All metal cans provide excellent light-blocking properties, but the lid must also be metal to ensure complete protection from light.
So how do these cans differ, and what are their characteristics?
Clinched Cans (also known as Crimped or Interlocked Cans)
Clinched cans are made by folding and interlocking metal sheets,
forming a secure structure.
They are the most common type of metal can, used for tea canisters, cookie tins, and gift packaging.
If you look at the side of the can, you can see where the metal sheets are interlocked.
Features:
✔︎ Low production cost and well-established technology, making them widely used in the food and tea industries.
✖ Lower airtightness, as the interlocked structure may leave tiny gaps.
Tea Storage Recommendation:
▪ Place tea leaves in an aluminum foil bag, seal it with a clip, and then store it in the metal can to ensure freshness and prevent moisture exposure.
Welded Cans
Welded cans are made by fusing metal sheets together using welding techniques.
They are commonly used for powdered milk cans, beverage cans, coffee bean tins, and seaweed cans.
Unlike clinched cans, welded cans have no interlocking joints visible on the sides.
Instead, you will see a silver welding seam (since the weld cannot be painted over). Sometimes, the batch number of the can is printed on this seam.
Features:
✔︎ Good airtightness, making them suitable for direct tea storage.
✔︎ Widely used in food and beverage packaging, offering good safety standards.
Tea Storage Recommendation:
▪ Tea leaves can be stored directly in the can, but using an aluminum foil bag inside is still recommended for better preservation.
Seamless Cans (One-Piece)
Seamless cans are manufactured using press molding, CNC machining, or sand casting techniques.
They are distinct from other types because there are no visible seams or weld marks from any angle.
Typically, these cans are made by machining a solid piece of metal or casting molten metal into a mold.
Common examples include pewter tea canisters and cosmetic containers, and they tend to be more expensive due to the complexity of production.
Features:
✔︎ Excellent airtightness, making them ideal for long-term tea storage.
✔︎ Elegant and luxurious design, often used for premium packaging.
Tea Storage Recommendation:
▪ Tea leaves can be stored directly in the can, but if the inner coating’s safety is uncertain, it is best to store the tea in an aluminum foil bag first.
The Importance of Lid Design
In addition to the structure of the can, the type of lid also affects airtightness.
Among various options, screw-on lids with sealing rings provide the best airtight seal.
Common Types of Sealing Rings:
• Rubber O-rings
• Gaskets
• Sealant coatings
• Molded plastic liners
For example, if a welded or seamless metal can has a metal lid, there will always be tiny gaps, no matter how tightly it is closed.
This is why powdered milk cans use soft plastic lids, as they provide the best airtight seal.
Similarly, if you check cosmetic cream jars, you’ll often find a gasket inside the lid, which helps prevent air from entering or contents from leaking.
How to Test the Airtightness of a Can
A simple way to check the airtightness of a can is to fill it with water and see if it leaks.
If no water leaks out, the can provides a good airtight seal, making it suitable for tea storage.
Final Tips for Safe Tea Storage
Regardless of which type of metal can you choose, it is recommended to store tea in an aluminum foil bag before placing it in the can.
Why?
▪ The safety of the inner coating is uncertain, and an aluminum bag adds an extra layer of protection.
▪ Even if the metal can is airtight, using an aluminum bag helps preserve the tea’s freshness for longer.
I hope this information is helpful to you! See you next time!
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