What materials compose tin cans?
Tin containers rank among the world's favoured packaging options, known for their ease of production, affordability, and versatility in colour, shape, and design. Despite their name suggesting otherwise, these containers are not actually made from tin. So, what materials are tin cans typically crafted from?
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Image credit: Author with Ai and Wei Cheng
Tin Cans – What Are They Made Of?
While commonly referred to as "tin cans," contemporary versions are rarely made solely from tin. This nomenclature originates from the late 20th century when cans were primarily fashioned from tin-plated steel, merging steel's robustness with tin's resistance to corrosion.
Presently, empty tin cans are typically constructed from various thin metals, spanning aluminum, steel, or iron. Although not universal, these small cans often feature tin plating. Since the 1960s, aluminum has emerged as the preferred material for small tin can production due to its cost-effectiveness and malleability, streamlining manufacturing processes. Aluminum mirrors tin's corrosion resistance, rendering it a viable substitute. For a deeper exploration of the industry's shift towards aluminum, refer to this blog post contrasting Tin Cans versus Aluminum Cans.
The scarcity of tin plays a pivotal role in the shift away from using it exclusively in can production. Despite being classified as a "common metal," tin remains relatively scarce compared to precious metals like gold or platinum. Global tin mining operations are limited, prompting concerns about future tin depletion. Consequently, crafting items solely from pure tin, especially everyday objects like packaging materials, proves economically prohibitive. As of August 2017, tin costs approximately US$20.61 per kilogram, in stark contrast to aluminum's price of US$2.1 per kilogram (LME, 2017). This significant price disparity incentivises manufacturers to opt for alternative metals. Thus, the majority of modern empty cans are crafted from aluminum or other cost-effective alloys.
Classic Tin-Plated Cans
Tin foil stands as the sole product crafted purely from tin. Commonly utilised in scientific experiments and for wrapping items like chocolate bars, tin's ability to be flattened into extremely thin sheets enables vast plating production from minimal tin quantities. Aside from tin foil, this plating is frequently applied to conventional containers. It's estimated that a pound of pure tin can yield up to 130 square feet of tin foil or plating (Sciencing, 2018), rendering tin highly sought-after for plating purposes, often applied to pure metal cans.
Beyond its malleability, tin's resilience as a plating material stems from its non-reactivity with oxygen, preventing rust, tarnishing, and corrosion.
Presently, the majority of global tin usage is directed towards manufacturing tinplate cans. These cans predominantly comprise steel or iron, layered with tin plating, constituting only 1 or 2% of the entire can. This plating serves as a protective coating against environmental elements, rendering it suitable for various commercial applications, including tin can wrappings.
Tin cans primarily fulfils roles in food canning, cosmetics storage, medicine containment, and candle preservation in candle tins. Conventional metals tend to react with acids present in these substances, leading to corrosion and contamination. Historically, lead wrappings posed significant risks due to toxin leaching. In contrast, tin-plated metal cans offer safety and durability, resisting acidic compounds and safeguarding contents. However, their notable drawback lies in their weightiness compared to aluminum tins, resulting in higher transportation costs and decreased convenience.
Contemporary Tin Cans
Broadly speaking, tin-plated cans are viewed as the conventional method for can production. Nowadays, the predominant material used in crafting small tin containers available for purchase is aluminum or various treated metals. The choice of material depends on its ease of shaping and its ability to resist rust and corrosion. Both traditional and modern iterations of tin cans excel in canning applications and are recyclable. This recyclability enables manufacturers to remove the tinplate layer and reuse the iron or steel for scrap metal purposes.