HomeRoast Digest


Topic: Delayed Crack (4 msgs / 69 lines)
1) From: Bob Hazen
I roasted some Sulawesi this morning, about 10:00 AM.  It has been outgassing on the counter in an uncovered bowl since then.  While fixing something to eat for dinner, one of the beans went CRACK!  Eight hours later!  Big snap, probably more obvious because of the open container.  Made me jump.  Sounded just like an arc in one of my circuits at work.  I was looking for smoke out of the toaster, when I realized it was the coffee.
First time this has happened.  Anyone else?
Bob
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2) From: Bill S.
Bob,
Not quite the same experience, but I have noticed that when dumping hot
beans (roasted to FC) into my cooling tray, I will have none to several
cracks right at the time of dumping.. I don't know if its momentum roasting
into a second crack, or some kind of a contraction crack upon rapid
cooling..
Bill
On Sat, Aug 2, 2008 at 10:45 PM, Bob Hazen  wrote:
<Snip>
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3) From: Bob Hazen
Maybe I observed something similar.  Cracks on roasting make sense to me. 
We put some violent stress on the beans with a large amount of heat in a 
short time.  Could be that on cooling all those stresses aren't completely 
relieved or are relieved in a different part of the bean.  The Sulawesi 
beans are fairly large, so perhaps the residual stresses were significant 
enough to get a crack from the changes that occur during rest.
Bob
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4) From: raymanowen
In freezing a tray of ice cubes, you're removing heat slowly, and there is
no cracking.
Add heat to the frozen tray to melt the cubes enough to remove them, and the
ice cracks.
Freeze a piece of wood, and it's very quiet. Set it on fire like a certain
company roasts their coffee, and it makes noise as it burns and gets hotter.
Cool it as fast as you can, like with a fire extinguisher, and it gets real
quiet again.
Stress relief is enjoying a cup of whatever comes out of your brewer. Cracks
due to rapid cooling are like the square root of a negative number.
Cheers, Mabuhay -RayO, aka Opa!
Got Grinder? Imagine Big Crack; DOH! Take up a special collection or have a
Bingo tourney...
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