Creating Crystal Clear Ice Bricks For Your Scotch
Full credit for this goes to Geoffrey Grosenbach, whom I visited a few weekends ago at his lovely home. While there, he pulled out a small tray full of 3-square inch bricks of ice and plunked one down into a glass, which he then filled with dark Vermouth.
The ice instantly turned translucent and looked like a tiny berg floating just under the surface. He told me how he recently had been getting into “making ice”…
Don’t over extend yourself there Geoffrey
Can’t help it — it sounds so silly. “Making ice”. But as it turns out it quickly can turn into an obsession. At least it did for me.
A Cooler, a Serrated Knife, and a Hammer
Over Thanksgiving I decided to give it a try. It’s a deceptively simple process:
- Put about a gallon of water into a small cooler — the personal lunch cooler size.
- Freeze for 24 hours or so, depending on the desired thickness of the ice.
- After 24 hours (or so), push the knife down the side of the frozen surface and drain out the water below. Then remove the brick.
- Trim off the edges and smooth it out, then score the top in vertical lines. The scoring is enough (usually) if the water is purified to fracture the block along the score. If not, score down about 1/8th of an inch and tap with a hammer. This will fracture it in a straight line.
Continue doing this until you have some little bricks.
That’s all there is to it. Now plop this into your favorite glass and pour whatever you like over it. I bought a Lagavulin 16 and it was gloriously chilled, without any melt from the ice.
Which is the secret here. The less melt, the better the flavor. But why doesn’t it melt as fast?
One day while traveling in the Highlands in Scotland (on our Big Trip last year) we did a little day trip to Loch An Eilein — an amazing little lake just outside of Aviemore with a 13th century fortress ruin right in the middle.
Almost the entire lake was frozen around it and the day was blue and glorious. I can’t even begin to tell you how wonderful this place is to American eyes — we just don’t see things like this normally.
Anyway, my youngest daughter was quickly picking up the little ice bricks along the edge of the lake:
The thing they loved the most was how utterly clear the ice was. Almost perfectly clear as you can see. We marveled at it for a bit then we had a fun game of ice-skipping to see how far out on the lake we could toss the things. Lots of fun.
The reason I bring this up is that we were homeschooling while on this Big Long Trip of ours, and this was a perfect time for a lesson in physics and crystallization. Being a former geologist (that’s my degree) — I had to study these things in college and it’s fascinating to me.
Crystallization Speed, Direction, Density and Clarity
There is a really fascinating effect in geology called “Crystal Fractionation”. In summary it’s when minerals with a higher melting point cool down toward the top of a column of magma and, basically, “fall out”. The result of this is a lighter column of magma with minerals that have a lower melting point (silica-rich stuff like feldspar and quartz).
The “heavier” minerals (the ones with a higher melting point) tend to be more metallic — magnesium, iron, etc (“mafic minerals”) and thus are literally heavier. They drift on down to the bottom of the column and typically stay there. The lighter, less dense stuff gets pushed to the top and will actually trap water within it (which is weird).
The density difference squeezes the column of magma (eventually) to the surface — at which point a critical inversion happens (in other words: an explosion). Mt St. Helens, Mt. Ranier, Mt. Hood — these are “Andesitic” volcanos (Andes-like) which means their magma has been highly fractionated and explodes. The latest one being Mt. St. Helens… the other ones will happen at some point in the future.
Volcanos in Hawaii and Iceland don’t do this. Their lava is dark and heavy in mafics, so they ooze and flow. These volcanoes sit on top of a “hot spot”, which pipes magma up from deep in the earth. No one knows why — but there is no cooling so up it comes full of iron and goo.
OK — that was a long digression but the process is important. We’re basically doing the same thing with our ice but in reverse.
When a liquid crystallizes it “nucleates” — meaning all it takes is one crystal to form and then others glom on to it and it spreads. In our volcanos above, the crystals fall down.
In our ice, they fall up, because ice is lighter than water. Well, that’s half true: they’ll actually form at the top and squeeze the bad stuff down because we’re cooling from the top. Either way the crystals are at the top.
Anyway, we have to give that ice the time it needs to slowly nucleate — do it too fast and the crystallization process goes off everywhere quickly, trapping gases and impurities.
We want clarity. So we put the water in a cooler guaranteeing that the source of cold comes from the top, slowly. If the container is too small or the ice freezes completely the impurities will get trapped and all is lost.
The speed of the process is critical. If the lattices form too quickly they will trap gases in the water and we’ll end up with the same ice we get in our ice tray — full of gases, kind of crumbly.
You can also do this with boiling water because the gases trapped within the water are boiled off. Same with purified/filtered water because gases tend to stick to impurities — remove the impurities and you remove a lot of the gas.
That’s too much work for me. Dumping a gallon of tap water into a cooler works pretty well.
Ice Nerds of The World, Unite and … Have a Whiskey
I’m sure that might be more than you want to know… until you pour whatever you’re drinking into your glass and watch this lovely little brick turn completely translucent. And then you begin to wonder.
The neat thing too is that you can use tap water — even if (like where I live) it doesn’t taste so good (chlorine, etc). All those impurities (for the most part) are left behind during the slow freeze process. You might still want to use filtered water if you can — just to be safe.
The big block of ice will also melt much, much slower due to surface area/mass of ice. With a single pour I’ve retained as much as 80% of the original block. I could probably pour 3 more if I wanted too (which I can’t because age) but I’ve taken to rinsing the ice off and putting it back.