# Why is my grind changing?



## EarwaxUK (Jan 19, 2014)

Wow, it's been quite a long time since I've been on the forum. Trying to get my PhD finished means I've had almost no time at all recently.

But, I've got 10 minutes and I've had a burning question for a while. This might not be the best place for it but it'll do for now.

Being a research scientist, I'm used to keeping a lot of notes and I do this when I pull every shot (pretty much the same as my lab book at work really).

I've always noticed that sometimes my grind changes and I've never been able to work out why and I was wondering if you had any ideas. I've been looking through my notes and I've not noticed anything specific and the only thing I've been able to tally in with it is changes in the weather - specifically when it's been dry and then started raining.

To illustrate this, a few days ago I pulled a shot in the morning which was lovely. I brewed to a 1.6 ratio and I got that in 33 seconds. Later that day it hammered down with rain and I pulled another shot in the afternoon. No changes to any settings and my grind looked too fine and clumpy. I pulled a shot and choked the machine.

Is this really all down to the humidity/temperature?

The scientist in me doesn't like the fact that there's a variable at play which I can't identify...!


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## Jason1wood (Jun 1, 2012)

Do you clean the grinder out after every grind, I noticed mine kept grinds in the chute, and when I grind later on the previous grinds were shoved out into the PF by the newer grinds. Could the old grinds cause a variable?


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## EarwaxUK (Jan 19, 2014)

Generally I do clean the grinder out. In fact, I've spent so long being trained to write down everything, I've actually made a note of it.

Having checked, making sure I've flushed out any old grounds is more likely to make a difference to the flavour but not the pour. I have almost always noted that the coffee is a little sour when I've not cleaned the grinder but the shot times are pretty consistent and certainly don't correlate with grinder cleaning.

Definitely going to clean out the grinder more though - it's clearly making a difference to the flavour...


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## Mrboots2u (May 10, 2013)

Humidity can play a part in having to alter the grind to achieve same extraction


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## EarwaxUK (Jan 19, 2014)

I understand it can make a difference, but I can go from a nice clean flowing shot to completely choked which seems like quite a big difference.


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## Jason1wood (Jun 1, 2012)

Haha well you are the research scientist. Haha


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## EarwaxUK (Jan 19, 2014)

Haha, yeah. I might be overthinking the whole thing...

I have got an idea for an experiment with a humidifier and a volumetric particle counter...


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## Mrboots2u (May 10, 2013)

EarwaxUK said:


> I understand it can make a difference, but I can go from a nice clean flowing shot to completely choked which seems like quite a big difference.


I wouldn't expect it to make that dramatic difference ...


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## The Systemic Kid (Nov 23, 2012)

Can you outline the experiment Chris? Love the idea of someone having their own volume particle counter!


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## EarwaxUK (Jan 19, 2014)

Well, I don't have my own but we've got a Coulter Counter in the lab, as well as a variety of flow cytometers (a CyAn ADP, a MoFlo, an Astrios and a LSR Fortessa for those who are interested).

If I had the time and the freedom in the lab I'd humidify beans at different levels and then grind them before assessing the particle size, volume and how much they stick together. In theory it would be pretty simple. In practice, I suspect my boss would wonder what the hell I was doing!


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## The Systemic Kid (Nov 23, 2012)

Don't tell him


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## marcuswar (Aug 19, 2013)

Oh no... may be dsc's the mythical and illusive ZR-71 grinder should now be delayed even further until he can build a humidifier in to it


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## garydyke1 (Mar 9, 2011)

Humidity can make a difference. If all other variables and technique/prep are fixed its a likely suspect


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## gman147 (Jul 7, 2012)

One thing I found is that if my machine is near a window on a very cold day (as I was explaining to Jeebsy over pm) the cold from the window can make a huge difference to the extractions. Similarly if it's a very hot day in summer; I may need to change the PID by a degree or two to get the same output.


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## kikapu (Nov 18, 2012)

As well as the above comments are you checking the amount of coffee in your basket every time? The MC2 as am sure you know can retain a fair amount of grinds!! If your final weight in the basket was an extra 0.5 grams or more could make a significant difference to your shot times!


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## EarwaxUK (Jan 19, 2014)

Yes, I weigh my dose to 0.1g every time


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## kikapu (Nov 18, 2012)

EarwaxUK said:


> Yes, I weigh my dose to 0.1g every time


Ok thought you might!!


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## EarwaxUK (Jan 19, 2014)

kikapu said:


> Ok thought you might!!










yeah, I'm quite a spectacular nerd...


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## The Systemic Kid (Nov 23, 2012)

EarwaxUK said:


> yeah, I'm quite a spectacular nerd...


No, you're just eliminating one variable


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## EarwaxUK (Jan 19, 2014)

I like the way you think!


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## Wando64 (Feb 28, 2011)

I asked a question some time ago on the forum about the distribution of different coffee type grains in a blend when grinding small quantities.

I think on the whole people thought it a non-problem, and I would tend to agree with that conclusion.

However, as a scientist you will agree that this too has the potential to cause variations.

If you set your grinder for a 70%-30% blend, it is not impossible that the next time you scoop 18gm from the bag you might end up with a 50-50 blend or maybe 40-60.


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## Jon V (Feb 24, 2014)

Hi.

I am having a similar problem with my Vario: http://coffeeforums.co.uk/showthread.php?15406-Vario-inconsistency


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## EarwaxUK (Jan 19, 2014)

It would be as near as makes no difference to impossible for it to always be the same. The best you can hope for is a homogeneous mixture which you can do easily at home.

You're right though - it could certainly make a difference, albeit a small one.


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