High ABV after many years in the cask – I'm confused

I'll stick up a review soon, when I get organised...

Different rates of evaporation I guess. Constitution of the cask, ABV of the spirit going in, surrounding conditions. All these play a part.

[I've updated the discussion title to be more descriptive]

It's not unheard of. I was gifted a Rare Malts Mortlach that is 22 YO bottled at 65%

There's probably a lot of microclimate gobbledygook that could explain what ABV changes the barrel(s) experienced over those 17 years, but my guess is that the main reason is entry proof.

Distillers in Scotland normally dilute the newmake to 63.5% ABV when they fill it into barrels. Some don't do that. (Bruichladdich is the infamous one.) My hunch is that Ledaig—or more likely, the independent bottler who had the barrels filled on contract by Ledaig—had the newmake go into the barrel undiluted, at whatever ABV it had coming off the still.

And then from there, 17 years of microclimate blah blah blah, and you have 65.8% goodness.

@Ol_Jas, that sounds like some very plausible blah blah blah.

I saw this video a while back, and it did an excellent job of explaining how the angel's share works. m.youtube.com/watch Around the 2 minute mark he starts explaining it, but the,whole video is great as i recall.

I have nothing to offer "fact-wise" but I agree with @Ol_Jas that the issue is probably strongly due to entry proof. Take Glenfarclas 105 for example. They were able to release a 40yo at 105 Proof (or 60%). Really??? That is crazy. As are the ABV's of many of the Rare Malt editions (most over 60% and 20+ years) released in the 1990’s (which were released by Diageo - therefore, not independent editions).

My belief is that it is High entry proof + inactive casks = High ABV Scotch.

@gfc that video is about bourbon. The situation is much different in Scotland. I think (just a guess) that an inactive cask (second or third re-fill) will be more able to maintain the proof of a scotch over the years.

Take Kilchoman. They have 5 year old whisky coming out well below 60%. And it is fantastic. Why? I think it is because of very active casks which are being selected for release now. I can only hope they are keeping back casks for a 10yo and 20yo release.

I could be very wrong (and in need of posting this under @Victor’s thread)

Anyone else have a thought?

Thanks guys.

I never would have considered the entry proof, you learn something new every day!