Humidity Requiring Radical Change in Grind?

[jrothstein]

Hi all. Can very high humidity require a huge change in grind? It is monsoon here in Tucson, and humidity has been elevated for weeks. This morning the outside humidity is 76%-just about off the charts here, though not that much higher than yesterday. Yesterday my Macap grinder (used for my wife's half-caf) produced somewhat slow but usable shots. Today I could not produce a drop of coffee in more than 25-30 sec on 3 different tries. Fed up, I turned the worm gear on the grinder 3 full revolutions-in my experience an extreme change that should have caused the shot to pour freely and complete in seconds. It produced a slow shot usable for a latte. My other grinder, for regular coffee, is a Ceado E5SD. In 4 tries, loosening the grind each time and on the fourth also dropping the beans from 16g to 15g, would not produce a single drop of coffee within 30 sec.

I use a Lelit Bianca which seems to be operating normally. Through the course of a year I rarely adjust the grind by a fraction of what I have been trying today.

Any advice, or suggestions on other variables I should consider, would be much appreciated.

Thanks!

Jeff

[palica]

I can have significant changes with beans of course, and sometimes with RH level. In your case, 3 turns sounds like a lot to me.
Did you clean your grinders recently? I had an issue in the past with a clogged grinder which was producing way too fine coffee and clogging my espresso machine. Once cleaned and vacuumed, everything went well, again.

[jrothstein (original poster)]

Day two report: the indoor humidity today is only 1% less than yesterday (34% vs 35%) and the outdoor humidity is about 5% less (71% vs 76%). Yet today my pours were back to the normal of the day before, and I had to tighten up my grinders. One of life's little mysteries, I guess.

[jrothstein (original poster)]

Day 3 report and a new hypothesis. Similar outdoor humidity, if anything less. Consistent indoor humidity. All my problems from the day before returned. To fill in details, I use a Macap M4 grinder for my wife's half-caf blend, and the Ceado E5SD for regular beans. We buy most of our beans from a local Tucson roaster, and I bought the current bag of decaf there last Saturday. The current regular beans are from a visit to Chicago in June. We vacuum-sealed and froze those beans when we got home. My first day of problems exhausted my supply of regular beans, so I took a bag of the Chicago beans out of the freezer (Thursday). I defrosted it all day and night and opened it yesterday morning. As reported, things seemed mostly back to normal. I stored the beans in a leftover foil bag with a gas valve.

Today was as bad or worse than Friday. I went through 7 or 8 shots to produce a barely drinkable latte and cappuccino. I kept turning the Macap's worm gear in half turns through 4 shots, unable to produce a drop of coffee in 30 seconds. For the last shot I had turned it 15 times, 7-1/2 full rotations of the gear. I haven't moved it that much in 5 years. The hopper has rotated just under a quarter turn-a huge amount. The last shot dripped slowly through the pour. With 16g in, I managed 30g of liquid in 56".

I then turned the Ceado's dial from about 1.3, which had been normal, to more than 2. The pour was very fast though the group head pressure gauge never registered more than 1 bar. I used the flow control dial to slow it a bit, drank the swill and gave up. I figure I've pulled 15 or 16 shots over two days trying to make a total of 4 drinks.

My mind keeps going back to the freezing and humidity issue. Sure seems like my frozen coffee changed over 24 hours to cause the difference in results the last two days. We've been vacuum-sealing and freezing coffee for a year now with excellent results. Maybe it's just this bag?

I'm going to buy some fresh beans today and try again tomorrow.

Also, as to the suggestion about cleaning my grinder, I doubt that is the issue since both my grinders have been affected in the same way each day, bad, better, bad. (And I do clean them regularly.)

I'd be very interested to hear others' experiences with defrosted beans.

[MCal2003]

Have never frozen beans. Beans are stored in 1qt mason type jars with the option of a manual pump vacuum system inside a dark cabinet. Home roaster for ~quarter of a century.

Regarding RH%. Indoor RH extreme range from summer to winter can be upper 60's to mid-20's. The transition is gradual. The huge daily swings when the weather changes abruptly can be 10-15%. These swings don't seem to really effect grind settings. Origin and roast levels do, but not significantly. For espresso I roast to FC into FC+ range.