Who knew? (The Rishiri Filtration Process, pt. 2)

The Rishiri Filtration Process, pt. 2

Hey, I’m Rusty. Welcome to our weekly newsletter, sharing the startup journey of Kamui Whisky K.K.. Each week the team will share a story as we set up a craft whisky distillery on a remote, volcanic island in the most northern part of Japan.

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This episode can read as a standalone, but do check out part 1 in the series for the deeper story:

The Rishiri Filtration Process, pt. 1

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So we have an idea, some volcanic rock and, hypothetically, we know it’s possible to filter whisky through it. But we really don’t know anything. This is all an experiment. The volcanic rock could be poisonous. We might not be able to figure out an effective filtration system. It may make the whisky taste like crap. We don’t know.

But I was happy this team decided to play along, because what we did ultimately find with the volcanic rock filtration was mind-blowing.

Before I begin to explain what we discovered, I want to take a second to acknowledge the team at South Dakota School of Mines (SDSM)*.

SDSM Team & Rusty

I’m on a high that we even got a team. Then on a double-high that we have two teams, from different disciplines. And then, on our first intake call, I get in to a triple-high, it sounds cheesy but, holy shit, I was so impressed with everyone.

The best way to describe this team is: passionate and on point. From the very first meeting to now, I have been both impressed and thankful on each call. This team is forward-thinking, proactive, inquisitive and, most importantly, work with passion. They have been weeks ahead of me throughout this project and have kept both the project, and me, on time. I cannot say enough good things about the team at SDSM.

Now back to the rock.

Our first meeting focused on the overall concept and how to make it into reality. To get started we needed to answer two questions:

1) Is the rock toxic?

2) What filtration method was best? Soaking, stirred, or pumped?

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But first, we need to acquire some volcanic rock Rishiri.

Here’s how that happened:

I message Casey, asking for volcanic rock; he sends Kosaka-san up to the volcano with a pick axe; Kosaka-san comes down and tells Casey they have 3 types of volcanic rock on the island, which one does he want?; Casey: ‘all 3!’; Kosaka-san drudges back up the mountain again with the pick axe, mails the rock to Casey in Tokyo; Casey re-packages it and mails it to SDSM.

And by the way, mailing things internationally amidst a pandemic is a real pain, let alone volcanic rock. A whole bunch of hoops had to be jumped through (if you need an idea of what that may have felt like read Casey’s post on licensing).

Once the team receives the rock, they break it down and name the 3 different samples: ‘Solid Sally’, ‘Porous Pete’, and ‘Big Red’.

You know, traditional Japanese names.

The first thing we do is test for toxicity. Basically, the volcanic rock went to a lab that conducted every test possible to see if the rock was contaminated with anything that would poison, maim or kill anybody. Good news - nothing! Not toxic. Our volcanic rock is good as gold.

Next we turned to the question of which filtration system to use. We wanted to base the decision on taste. Specifically, which method influenced the taste the most.

For the 3 different volcanic rock samples, the team soaked each of them in whiskey, shook them, and filtered whisky through each sample type using a pump. After many, many samples, the team concluded that pumped filtration had the biggest effect on the whiskey. They noticed the most change in the flavor profile, but they weren’t exactly sure why.

From there, we took each volcanic rock sample and pumped alcohol through it to see what happened. We used fresh distilled whisky from our friends at Black Hills Contraband. The initial test was to filter the whiskey through each type of volcanic rock, separately, for 1 hour.

You’d think that 3 volcanic rocks from the same small island wouldn’t be that different from each other, but we found that ‘Solid Sally’, ‘Porous Pete’, and ‘Big Red’ were very different to one another!

We took each of those samples and held several blind taste tests with different groups. Overall, we had 40+ testers. And what the testers reported they tasted shocked everybody. The students were so shocked they called me super excitedly on a Friday night. The rocks really do change the flavor of the whiskey! Not only does it mellow the whiskey, it actually changes the flavor.

Me, ‘In what way?’

The whiskey is much smoother after the filtration and each rock uniquely changes the flavor of the whisky. Like one makes it sweeter, and the other is more like dirt, but in a good way.

I’m so excited about this. Immediately I began thinking of all the ways I can use this for our Rishiri Whisky.

The next step was to do more tests, and have another blind tasting, but this time, I wanted to experience it for myself.

The 2nd deep test was to filter whiskey through each of the rock samples for 1 hour, 4 hours, 8 hours and 12 hours. To see if the amount of time spent filtering affected the whiskey at all. Again we set up a blind taste tests with 30 or so people afterwards.

I flew up to Rapid City (catching covid on the way up, or down; I really don’t recommend it) and sit with the team for our second, but not final, tasting.

Right away I notice how much the volcanic rock takes away the alcohol sting. We were tasting pure moonshine. Straight alcohol. But this stuff was going down fairly smooth.

The second thing I notice is that, one gives me a distinct flavor, another does nothing for me, and then third one also has a distinct flavor. I was fascinated.

Solid Sally adds a sweetness. Porous Pete gives it an earthy flavor. And, despite its name, Big Red showed the least amount of change.

Very similar to how the three different Rishiri spring waters changed the flavor of the whiskeys, each volcanic rock not only mellowed the whiskey, but also changed the flavor.

The volcanic rock filtering system designed by SDSM, and the 3 different types of volcanic rock available on Rishiri, from 3 different eruption cycles, opens up so many possibilities for our whisky. I’m so excited about the flavor profile we can craft at Kamui Whisky K.K.

* Casey and I have an amazing team surrounding us. Although we are the voices of the company, there is no way 2 people could accomplish all this on our own. At some point we’ll acknowledge the rest of the team but, for now, we’ll start with the SDSM team.