Many of you will be familiar with the tall, elegant Sapporo steel Sapporo can pictured on the right. It’s a lovely tapered pint glass shape, with subtle creases every half inch along its surface. You might be curious as to why cans are almost never this shape, how the standard beer can is made, and what sets this one apart from a manufacturing perspective. In this post, I’m going to hunt through the clues left on the can itself to diagnose how this thing was made, and how the manufacturing process elegantly dictates the product’s final form.
The story of the standard aluminum can is fascinating. It goes from a simple disc of aluminum metal to a fully formed can in a scant few steps. How It’s Made has done a very complete diagnosis of the process, and The Engineer Guy has a brilliant video describing the function of the pull tab. However, the process for making one of them has almost nothing to do with the construction of one of Sapporo’s steel cans.
When an aluminum can is being formed, a press pushes incredibly hard on a disc of metal, forming the bottom of the can and causing a thin wall of metal to come shooting up the sides of the press’s cylinder. This is why all aluminum cans have such a regular shape. They’re more or less extrusions. This isn’t the only way aluminum can be formed. There are aluminum bottles, which are most often cast and welded or made via metal spinning, and hybrid can bottles, which are formed through an extreme case of the necking process that’s used to put the lids on your standard pop can. However, the aluminum pop can is the most common by far.
The manufacture of the Sapporo steel can has much more to do with a soup can than it does a beer can. Soup cans are made from flat sheets of steel that are rolled into shape, fused at the seam where the rolled cylinder meets itself, and then capped top and bottom. You can tell the steel Sapporo can is made in this fashion because it has a raised seam at the back that’s made from a slightly different metal than the body of the can. After everything’s rolled and fused the can gets necked down on the top and bottom. You can see this in how the ridges disappear at the point where the diameter starts to reduce just before the top and bottom seams. This implies that a couple of rollers squeezed down on the can as it was turned, drawing the metal out and shrinking the can as it passed between them.
The ridges that you feel along a soup can provide strength, preventing the metal from oil-canning. I’m sure you’re familiar with the crimp-a clunk-a noise you hear if you lightly squeeze a pop can once it’s been opened. Soup cans are rigid and strong. If you have the chance to squeeze a Sapporo can, it’s pretty beefy, but it’s not because of the ridges. The fact that the shape contains two simultaneous curves, the circle cross section of the cylinder and the curve of the profile, gives it boatloads of strength.
So, why are the ridges there? Are they some kind of aesthetic decision? Are they some remnant of the original metal stock? Are these lines delineating latitude on some lilliputian Koreshan world? This is where, I feel, this design goes from being a fairly pretty but unremarkable mass produced object, to being a truly excellent example of aesthetics meshing with manufacture. The ridges are a hyper-efficient way of getting the metal to bend.
Take a look at this paper jellyfish lamp I tutorialized for CRAFT a couple of years ago. The 3d form is made from a flat sheet by adding in curves. Those curves are made by reducing the surface area using pleats. The same effect can be achieved in metal by squashing and stretching the metal along ridges. Metal spinning is an energy intense process that results in smooth forms with an uneven wall thickness. The same complex forms can be approximated, maintaining an even wall thickness, by adding ridges to a flat sheet.
What likely happens start to finish is that a flat sheet of steel is fed into a machine that cuts it to size, slams a sine shaped press into it at half inch intervals, gathers the two edges up as the form starts to turn cylindrical, joins them with a seam, spins the shape and necks it down, rolls on the top and sends it off to be filled and capped.
So, only one question remains: Why use steel? Well, steel stands up to the slam dance much better than aluminum. It has the kind of tensile strength that will let it bend and stretch without tearing even when very thin. The downside to all this is that it needs to be coated to resist oxidation and tainting its contents. So, you’ll notice that the inside of your Sapporo can has been coated with a plastic layer that separates the beer from the metal.
There you have it. An object that can be mass produced at a fairly low cost and adds heaps of value in terms of keeping the product safe, looking fabulous, and not getting all dinged up in transit. What’s elegant about it is the simplicity of manufacture, how the process of forming the steel stock into a cylinder leaves artifacts on the object’s surface that are not just inoffensive, but beautiful. I want, in my own work and in the greater world, to see things that think to use the machines by which they’re made to earn their poise, achieve their design, and realize their value.