Air Moisture vs Grind Setting

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Great Dane

#1: Post by Great Dane »

Hello Home Baristas :D

I have a question regarding air moisture and grind size.

Over the weekend I had been making a lot of food and my kitchen was very steamy, and moist. The next day I tried to pull some shots with my coffee I keep in a airtight container. The usual grind size I had dialed in for the coffee was way off. Shots were running too fast and tasted very sour. I had to almost max out my grinder on the finest setting it will go.

I know it is normal to adjust grind size after different moisture levels, but I am wondering if it's normal to need to grind finer rather than coarser?

Tseg

#2: Post by Tseg »

How long since you last used your beans? I keep my beans in an Airscape airtight container. My 2.2lb bag lasts me a month. Even so, with my Baratza Sette 270Wi, my micro-tune rings has to be tightened about 8 notches (a notch every 1/2 week) with every bag over the course of the month. When I get a new bag (usually 3-4 days after roasting) I tighten back up the 8 notches and all is right back on the money to produce a 2:1 ratio in ~25 seconds. My grind adjustments are like clockwork with the same bean and supplier I use. In summary, as my beans age, even in an airtight container, the flow continues to increase when the grind setting remains the same... 1 week to next fairly substantially.

Great Dane (original poster)

#3: Post by Great Dane (original poster) »

My beans are fresh. I do not think for me, that it's a problem of older beans. I went from one day to the other and it was just insane how much I had to tighten the grind setting.

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mrgnomer

#4: Post by mrgnomer »

After doing some cursory reading looks like humidity related to ambient temperature and even barometric pressure affects extraction. As the humidity rises coarser grinds are needed to maintain your target extraction rate. Still looking into how barometric pressure is a factor.

I do single dosing and weigh the doses to 0.1g both in and out. I WDT before filling the basket, tap to distribute level in the basket, WDT to get as even a distribution as possible and nutate tamp to seal the edges. My pucks are conistently solid and have no signs of channeling. Only differences are extraction rates with the same beans sometimes from one bean to another. It does seem to be related to humidity. On cold dry days I can almost go 10mm finer on the grind adjustment for a classic 2:1 30sec pour. On humid days it's hard to find the setting sometimes. Overdosing a bit helps especially with a VST basket.

I haven't tried stock baskets on dry days. Maybe if extraction resistance is the issue a basket with less holes might help.
Kirk
LMWDP #116
professionals do it for the pay, amateurs do it for the love

Great Dane (original poster)

#5: Post by Great Dane (original poster) »

mrgnomer wrote: As the humidity rises coarser grinds are needed to maintain your target extraction rate.

But this is what I am wondering about. Usually you would have to grind coarser not finer, when the humidity rises. I had to grind way finer which I felt was interesting.

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mrgnomer

#6: Post by mrgnomer »

Burr temperature is mentioned as a factor as well. Some consider it a bigger factor in grind setting than ambient temperature and humidity.
Kirk
LMWDP #116
professionals do it for the pay, amateurs do it for the love

jpender

#7: Post by jpender »

It takes some amount of time even for ground coffee to absorb moisture. Beans will absorb more slowly, relative to their mass. So I would imagine that if you only opened your Airscape long enough to pull out a dose, the amount of time your coffee was exposed to the humid air in your kitchen would be just a minute or three. I'm surprised if that would have resulted in enough of a moisture gain to affect your shots by that much. If that were the case one would also expect RDT to force one to drastically change the grind setting.

I wonder if something else is going on. If it were me, I'd try another coffee, one I was familiar enough with to be close to guessing the grinder setting for. If it's where it should be then the coffee really did change. If not then it points to the grinder. Why the grinder might have changed suddenly is harder to say though.

Just thinking out loud.

Great Dane (original poster)

#8: Post by Great Dane (original poster) replying to jpender »


I do think your right. I think everything points to my grinder. It is notably cold in my home, and I can remember touching the grinder that morning and it was ice cold. I think this could be the root of the cause.