# Bloom



## Osh (Jun 15, 2010)

Why do some coffees bloom more than others?

As an example, where I would normally use 17.5g for a double, for a different bean at the same grind setting I would use 14g - and this would expand right on the shower screen.

Would the freshness / age make any difference?


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## HLA91 (Jul 16, 2010)

In general the fresher the coffee the more bloom, its to do with the CO2 I believe in the same way as, if the one way valve on your bag of freshly roasted coffee is blocked then you will notice the bag will expand as the CO2 after roasting is given off, the water triggers it off as well.

If I went to my local supermarket and bought a bag of roasted beans and ground them I would probably get no bloom at all due to the age of the beans.


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## RolandG (Jul 25, 2010)

I believe there's also an element of water absorption/swelling of the grinds - no firm info, but that might vary with bean varietal? (I'm fairly certain density of beans does, so variation in swelling potential would follow from that?)


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## DonRJ (Apr 3, 2010)

Gee Osh, for a minute there I thought your espresso machine had exploded but you had made a typo when posting


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## Osh (Jun 15, 2010)

Now that would be an interesting experiment....


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