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An Astrophysicist Explains Your Coffee Grinder | JONATHAN GAGNÉ!

October 5, 2026 · 1 h 24 min

Show notes

Do bigger burrs make better coffee? Are flat burrs cleaner than conical burrs? And why can two grinds that look the same brew completely differently?

Astrophysicist and Coffee Ad Astra author Jonathan Gagné joins Rohan and Ben to unpack what grinders actually do to coffee. They get into particle size distributions, fines, burr seasoning, freezing beans and espresso flow, then tackle the coffee claims that sound certain even when the science isn’t.

If you’re new here (welcome), our show dives into some of the best coffee conversations on the internet, but we’ll always remind ourselves that at the end of the day, it’s just coffee!

CHAPTERS!
00:00 Why grinders became coffee’s big obsession
02:04 Meet Jonathan Gagné
03:11 APAX LAB
03:53 From astrophysics to Coffee Ad Astra
07:22 Are bigger burrs actually better?
12:08 Burr heat, extraction and grinder myths
16:24 Flat, conical and burr seasoning
17:45 Static, freezing beans and keeping coffee fresh
23:20 What particle size distribution really means
32:04 Why some coffees produce more fines
37:00 Should you grind coarser for filter coffee?
43:11 What the 300 grind tests revealed
48:49 How water moves through an espresso puck
58:34 Filter coffee claims that don’t hold up
1:01:58 Tamp pressure and puck preparation
1:06:53 Does “high clarity” mean better flavour?
1:13:23 What we still don’t know about coffee and water
1:18:43 How to question confident coffee claims
1:21:49 Where to find Jonathan

Explore Jonathan’s work: https://coffeeadastra.com/
Jonathan on Instagram: https://www.instagram.com/jgagneastrocoffee/

Want more coffee content?
IT’S JUST COFFEE!: https://linktr.ee/itsjustcoffeepod

Want to get in touch? Hit us up at [email protected] for any questions or comments.

Proudly sponsored by:
APAX LAB: https://apaxlab.com/

Thanks for listening!

#ItsJustCoffee #JonathanGagné #CoffeeAdAstra #CoffeeGrinders #CoffeeScience

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