Michter’s Small Batch Bourbon Sunlight Exposure Experiment

For my 200th post on Malt, I wanted to do something unusual again. I already performed a dilution experiment with E.H. Taylor bourbon and glass experiment with Glenfiddich 12 before. I might as well do another experiment.

At some point in our exploration of spirits, we all end up learning one of the proper ways to store whisk(e)y properly is to keep it away from heat and direct sunlight. There’s just something about U.V. rays that make whisky break down and/or accelerates the oxidation which makes the spirit give off unpleasant flavors. Fear not, though: you’re allowed to expose it under the sun for a short amount of time for photography purposes.

But, do we know what “sunburnt” whisk(e)y can taste like? Do we know how long it really takes for whisk(e)y to go bad due to direct sunlight exposure? Once whisk(e)y turns bad, how much worse can it get? This isn’t an original idea on Malt as Taylor did this experiment last year. But I wanted to re-do this with more detail.

The whiskey I’ll be performing the experiment on is Michter’s Small Batch Bourbon. I’ll be honest that this bourbon became the sacrificial lamb because I’m not a fan of the brand, the main reason being how they brand themselves despite still being mostly sourced. They’re also a brand that various drinking friends and trendy drinkers who I know enjoy very much. But I think it’s just largely due to its association with Billions and how they market themselves in Asia. (They’re bar pours in top bars in Singapore such as the Manhattan Bar.) It’s also one of the regular expressions in my stash that’s closest to going empty.

I know this isn’t going to be a flawless experiment, but I’ve done my best to ensure the least effect from other variables. To lessen the effect of oxidation, I bottled all of these at the same time in 30ml sample bottles of the same design. The color of the glass is said to be able to affect the rate of sunlight’s effect on the contents, so I just used clear bottles with the same design in case the thickness of the glass can be a factor too.

Where I took the photo of the bottles is where I left the samples. It’s an open area, which means it’s exposed to the sunlight all the time when it’s out. I left the samples there at 7 AM on March 4, then I retrieved the samples at the same time of day.Sample A is 30ml of normal Michter’s Bourbon. This is the control sample. Sample B is 30ml exposed under sunlight for 24 hours. Sample C is 30ml exposed under sunlight for 96 hours. Sample D is 30ml exposed under sunlight for 168 hours (one week).

Some things to note: I started this experiment in the first week of March. The Philippines is a tropical country close to the equator, so we surely get more sunlight compared to where most of you live. Our weather has been sunny all week, with temperatures ranging from high 20 C to the low 30 C depending on the day and the time of the day. March is also when summer starts, so we’re getting more sun. As a result, things are heating up again. Back in December and January, it would start to get dark at around 6 PM. Now, it’s still fairly bright at 6 PM. Darkness starts creeping up at around 7 PM. Should a reader from a different climate attempt to repeat the parameters I used, the result will most likely not be the same.

Michter’s Small Batch Bourbon Sample A (normal) – Review

45.7% ABV. USD $39.99 from K&L Wines. £53.95 from TWE. USD $66 locally. Batch #L170807

Color: Amber.

On the nose: Pronounced and sharp aromas of orange peels and orange peel oil. Behind it are light and mellow aromas of peaches, honey, vanilla, dried apricots, cherries and orange gummies. At the end are subtle aromas of cloves, shiso leaves, tannins, and varnish.

In the mouth: An overbearing taste of orange. It’s like drinking orange juice with some peels blended into it. The bitterness is followed up by cloves and more orange peel. After that are light tastes of pickles, vanilla, honey, tannins, leather, and peaches.


Very pleasant and balanced on the nose but horridly imbalance in the mouth. One might think this was an orange brandy. There’s too many upfront and enveloping orange tastes to make this an everyday sipper. The pleasant fruits I found on the nose were drowned away by the oranges. If I forced myself to drink this everyday, I might get orange trauma.

Although, I like how this isn’t like most bourbons that have strong sweet corn and vanilla flavors.

Score: 5/10

(K&L price; 4/10 at TWE and local prices)

Michter’s Small Batch Bourbon Sample B (24 hours) – Review

Color: Amber.

On the nose: The pronounced aromas of oranges are still there, but it’s not as sharp as sample A. Instead, it’s rounder. After that are also round fruity aromas: sakura flavored mochi with shiso leaves come to mind. With that are light aromas of cherries, dried apricots, peaches, and honey.

In the mouth: There’s still a sharp and enveloping taste of oranges but it isn’t as pronounced compared to sample A. With the lighter taste of oranges, I get light tastes of cloves, tannins, leather, peaches, orange cough syrup, cherries, and dried apricots. Some pepperines come out at the end with another light burst of cherries, dried apricots, and peaches.


I dare say being exposed to the elements for 24 hours has made this bourbon more balanced, hence better. The orange flavors have weakened allowing other characteristics to be more noticeable. This factor made this bourbon more enjoyable for me.

Score: 6/10

Michter’s Small Batch Bourbon Sample C (96 hours) – Review

Color: Amber.

On the nose: Initially flat like tap water. At the end of my breathing in, I get a whiff of the tail end aromas of orange peels followed by a sharp ethanol bite. After that is a quick whiff of cereals, tart fruits and peppers. It becomes flat again after that.

In the mouth: Surprisingly not flat. The orange taste is completely gone. Instead, I get bits of pepperiness accompanied by medium and long-lasting tastes of honey, cereals, peaches, dried apricots, cherries, perilla liqueur, roasted coffee beans and chocolate barley.


This is very unexpected. I thought when a whisky went bad, the aromas and taste would go at the same time. But it seems like the aromas broke down first. The elimination of the orange notes in the mouth completely gave way for the other flavors to be more expressed. Which turned out to be to my liking.

I’ll say that this has a great mouth, great enough to me to utter that these kinds of flavors I get in the mouth are almost akin to some of the 80s National Distiller’s bourbon I’ve had. But with the aromas being almost gone, it isn’t recognizable as a whiskey anymore, so I won’t give this a score.

Score: N/A

Michter’s Small Batch Bourbon Sample D (1 week)

Color: Amber.

On the nose: Surprisingly sharper than sample C. The ethanol here is, unexpectedly, still lively. Behind this sharpness are persistent aromas of toffee and varnish.

In the mouth: Almost completely flat. This is like tasting peppered water flavored that’s been run through a caramel candy factory then flavored with drops of peanut oil, orange peel oil and cherry oil.


The result here is also very unexpected. I thought this was going to be the sample that was just completely devoid of any character. Yet, spending 48 more hours under the sun somehow made the nose better. This same amount of time really ruined the mouth though. The fruity notes I liked a lot are gone. It’s just a confectionery mess.

Score: N/A

Overall Conclusions:

A lot of my hypotheses for this experiment didn’t go the way I expected them to.

Let’s start with the color. You’ll notice that all my notes say it’s amber. Looking at the image above, there also aren’t any noticeable variations with the color. Without any scientific basis, I initially expected the samples that had been exposed more to turn somewhat hazy… but they didn’t. Let this be a lesson that you can’t tell if a whisk(e)y has gone bad just by looking at it.

Sample B shows that whiskey spending 24 hours under the sun just does not kill a whiskey, but even made it better. The imbalance caused by the overbearing orange flavors got toned down, which allowed other flavors to be more noticeable.

Is this what an oxidized Michter’s bourbon is like? If so, then an accelerated oxidation effect via direct sunlight exposure just may be able to improve some whiskeys.

Sample C and D really shows how prolonged exposure to direct sunlight can affect a whiskey. I’ve noted the huge changes on the nose and in the mouth. The nose went really bad for sample C, but in the mouth, it went really, really well. Sample D’s nose and mouth really degraded after a full week’s exposure.

What are the lessons here? One: you can’t tell if a whisk(e)y has gone bad just by its appearance. Two: judging by this very small sample size, a whisk(e)y being exposed under direct sunlight for 24 hours can be beneficial to it. I guess it just depends on how the different flavors react.

What could I have done better? I should have had seven samples for each day of the week, but at the time of starting this I only had four. Next time, maybe I can also try experimenting with a whisk(e)y that’s been exposed for one, two, three and four weeks.

What else can I do differently next time? Since every spirit is different, it can be surmised that the result will be somewhat different when this experiment is performed on a Scotch, or a rum, or a brandy. Maybe a spirit with less or more cask influence will fare better or worse? I also think ABV is a factor; higher ABV spirits tend to be more resistant toward the elements. One of the reasons fortified wine was created was so the wine could survive the long journeys at sea.

I’m open to any suggestions for when I try this again next time.

  1. Pbmichiganwolverine says:

    As an ex-research scientist, I’m thoroughly impressed. It’s fair to say that oxidation broke down the chemical structure. But it sounds like it didn’t break down the alcohol structure, instead it acted on the esters and fatty acids (which gives the aromas and taste).
    If I was still in the field, I’d offer to run the samples through a mass spectrometer, and see exactly what’s being broken down.

    Wondering if a similar experiment can be done with another storage variable —-like temperature. What happens if you store a vial in the ambient room temperature (control), vs refrigerator, vs somewhere that the ambient remains steady (basement ) vs somewhere where the ambient has wild swings (attic )?

    1. John says:

      Hi PB, nicely put. Out of curiosity, why a spectrometer and not a geochronometer?

      That’s very interesting and thanks for the idea. I’ll have to modify that since basements aren’t exactly a thing in Manila. Strong rains and threats of flood are an issue here. Sounds like I’m going to need a lot of 1 whisky for this. 4 variables and different time tables.

  2. PBMichiganWolverine says:

    God no…unless the instrument has changed, I think a geochronometer is for radioactive decay. We don’t want that in our Michter’s. The mass spec would shoot the particles of Michter into a nitrogen wall, and the individual components would break up into a spectrum. That’s when hopefully we can see what’s changed in the samples vs the control.

    1. John says:

      Hi PB, for some reason that ended up being a typo. I mean a gas chronometer. Since this is the equipment distilleries have to measure the compounds in their distillates.

  3. rob thomas says:

    Thanks for all that effort, John.
    Any thoughts on indirect vs direct sunlight?

    I kept my booze ‘out on show’ for years, and never noticed any big negative developments, even on those out for 24 months (although they were often in dark bottles). This was under indirect light, but in a room full of floor-to-ceiling windows.

    All the good stuff is now in an antique wardrobe in the kitchen, so the whole family knows from the big creaking sound when I’m taking a snifter…

    1. John says:

      Hi Rob, I think indirect sunlight won’t hurt the booze. I’ve been to rooftop bars where the bottles are displayed in well-shaded areas and they don’t go bad.


  4. Jonah says:

    Rob, if you don’t have a kitchen that’s considerably larger than mine i would be more worried about temperature (-fluctuation) than indirect sunlight. Spirits don’t like getting hot and/or changing temp rapidly, as can happen while preparing a big meal for the family. At least in my kitchen spirits have a much shorter shelf-life than in the living room…

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