Friday, 20 April 2018

Why Staples are Underrated

by Katie O'Flaherty




The humble staple. Not given a second look in day to day life, we all too often overlook the small triumphs of engineering that make our lives so much easier, and our paper so much more organised. After my surprisingly passionate (to the extent if surprised me), exclamation to the defense of staples after a classmate stabbed themself on the tiny piece of steel that ‘staples are awesome’, the confusion and amusement of my classmates led my thoughts to wander to those of what does make staples so ‘awesome’. The obvious answers, that they can come in many sizes, with larger staples being used with a hammer, and smaller from a small, simple mechanical stapler, or from a ‘staple gun’ (arguably the coolest way of dispensing staples), and thus the many uses that come from that could be enough to qualify them as ‘great’ or ‘useful’, but certainly not ‘awesome’. The use of staples in medicine to close incisions and wounds, thus healing and potentially saving lives, could be seen as ‘amazing’ from a certain perspective, but still not mainstream ‘awesome’.

Maybe the design and engineering of the staple will shed light on their ‘awesomeness’. The ‘crown’ (the top of the staple) provides a larger surface area for the pressure exerted on the stapled object, thus reducing the likelihood of tears, which is especially useful in thinner materials such as paper. The legs can also be used to wrap around an object without puncturing it, the crown being used to pin the object, a quality used in situations such as when fastening electrical cables to wood frames.

For me, however, the real beauty lies in the Chemistry, and the simplicity behind it. Modern staples are usually made from zinc-plated steel wires, with more expensive staples available in copper and stainless steel. Copper’s malleability allows the staples to bent into position relatively easily, a basic chemical property from the uniform rows of copper atoms being able to slide over each other. Zinc-plating on the steel prevents oxidation (rust) by forming a barrier, and can act as a sacrificial anode is this barrier is damaged. The zinc oxide formed does not damage the steel’s surface or structural integrity, thus if undisturbed, the zinc oxide can act as a barrier to further oxidation, thus protecting the hidden inner steel staple, and safely keeping the paper together.

Stainless steel is one of the modern day to day miracles of materials engineering, developed almost purely by chance by Chemist Harry Bearley in a laboratory in Sheffield in 1912, while trying to find a new alloy for use in gun barrels, with fears of impending war motivating arms research. In the months-old pile of discarded ‘reject’ alloys not suitable for the job, he noticed a single gleam lodged amongst the other dull and rusted sampled. Initially the metal was marketed as ‘Staybrite’, and by 1929 over 25 tons of stainless steel was marketed and sold in the US alone. Steel on its own is an alloy of iron and carbon, and unprotected carbon steel reacts and rusts readily (reacts with oxygen) in the presence of air and moisture, and the resulting iron oxide on the surface occupies a larger volume than the original steel, thus it expands and flakes off as the surface is brittle and fragile, exposing the steel to further oxidation.

On the other hand, stainless steel contains a minimum of 10.5% chromium in the alloy. This chromium reacts more readily with the oxygen than the iron, rather like a very polite guest, reacting instead of the iron to form a microscopically thin layer of inert chromium oxide on the surface. This layer of chromium oxide is not only see-through, thus invisible to the human eye so we are unaware of it, but also acts as a self-healing layer, as, if scratched, the chromium in the stainless steel underneath simply reacts to ‘fill in’ the hole. It is this layer of chromium oxide that means we cannot easily reach the steel underneath; we are one of the first generations to not be able to taste our own cutlery. The structural integrity is further proved by stainless steel’s use in numerous iconic pieces of art and architecture, notably including New York’s Chrysler Building, as well as the humble staple.  

Overall, I find my exclamation to the defense of staples to be rather well justified, even if I still can understand the bafflement of my classmates, with the minute engineering, yet mass-production of such a clever yet overlooked object, the simplicity and effectiveness of which are undeniable by anyone, even those who have fallen victim to their sharp edges.



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