Filtration

At the end of the long column line, the alcohol that emerges already has barely any smell or taste, even before any further processing. This sets it apart from a raw spirit straight off a simple pot still, which often needs to be redistilled several times.

Many vodka brands promote an additional step after distillation, filtering through birch charcoal, wood charcoal, or quartz sand to capture any remaining impurities. In the publicly described production process for Koskenkorva and Finlandia, this step is absent.

The reason lies in what happens earlier. The more than two hundred distillation stages in Ilmajoki's column system already separate out methanol, fuel oils, and other congeners before the alcohol ever leaves the facility. An additional filtration step would have little left to do on an already highly pure distillate.

EU regulations require vodka's alcohol to reach at least 96 percent by volume before dilution in any case, essentially pure ethanol. Only after that is it brought down to drinking strength with water. The regulation says nothing about how many additional filtering steps, if any, should follow.

Even the dilution process requires minimal effort. According to the distillery, the spring water from Rajamäki is so clear that it's used without any dedicated filtration system. While other producers invest heavily in purifying their water, Altia simply points to the natural filtering provided by the esker.

In Russia or Poland, charcoal filtering is traditionally seen as the final purity step before bottling. Finnish producers don't emphasize this image in their own descriptions. Instead, they point to the column technology itself, matter-of-factly, without any romantic imagery of the tree the charcoal came from.