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Topic: Problem with roast consistency... (7 msgs / 175 lines)
1) From: Eric B. Stauffer
I have having problems with bean consistency in my roasts. I started
roasting to somewhere around full city but have backed off to get a brighter
cup. When I was roasting toward the dark end, I had no problems getting my
beans all to the same degree of roast. However, since backing off I have
much more of a "speckled" look.
It seems to me that slowing down the roast might help with this. My roaster
is a Poppery Mark I.
Any help for this newbie?
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2) From: David Westebbe
On Sat, 24 Aug 2002, Eric B. Stauffer wrote:
In my limited experience, you are on the right track.  You can either
modify your machine, or modify your technique.
Try using less beans, so you spill more heat into the air.  If you use few
enough, the roast will stall prior to first crack, and the beans will all
heat up to the same point, and the same color.  Then you can put something
over the outlet to slow the air and keep the heat in the chamber.  Before
I installed a dimmer, I used to use a pair of work gloves or a metal
measuring cup to do this.
Alternatively, you can open up the air inlets into the roast chamber to
increase the air volume and reduce the temperature.  But since you have a
classic, rare, hard to replace Poppery I, with a cast chamber, I woudn't
do that.
My theory is that with high temps, you need fast bean turnover to heat
them evenly, and by cutting down on the temp, a slower turnover is OK.
Using less beans, all other factors being equal, will both reduce the temp
and increase the turnover rate.
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3) From: Robert Cantor
You are right.  From the big book of roasting formulas*:
consistency of bean donness = a(time * agitation) + C.    The faster you
increase temp, the less time the beans have to all get equally hot.  The
slower you move the beans, the more time you have to get localized hot
spots.  In response to your questions, 1. a and C are constants based on
your machine, temperment and consistancy measuring equipment; and 2. yes,
yes, but that's why you don't write "big books of formulas".
The most consistant roast is when all the beans are burnt to a crisp.  As
long as all beans are beyond the too light, sour stage, and none are to the
burnt stage, some degree of inconsistancy adds complexity to the roast.  How
much inconsistancy is good is a matter of personal preference.  My last ISH
roast (3 d ago) I roasted some very light which had an early but not
overpowering brightness transitioning smoothly to a carmel finish, and some
to almost second crack and combined them.  The resulting brew had all the
best that ISH had to offer.  Could I do it again?  Who knows?  But I got
lucky that time!
*Invisible ink press, c 1997, 2000, 2002
Bob "yes, it's a joke" C.

4) From: Ed Needham
Inconsistency is preferable if a balanced, or almost blended taste is
desired.  Heck, I roast one varietal both light and dark and add it to some
of my espresso blends every once in a while to bring out certain
characteristics.  If the most intense flavors of a great coffee are desired,
a roast with evenness, to bring out those characteristics is desired.  A
blend, or uneven roast can be quite drinkable, but for enjoying the varietal
distinctions, careful, even roasting is a must.
Ed Needhamhttp://www.homeroaster.comed

5) From: John Abbott
The technical name for this is from the French "blend" or mélange. I did
lots of that unconsciously while learning to roast. I would run several
sessions and find that the combined blend tasted superior to a single
session. When I posted this a couple of years ago, Tom was good enough
to send me the proper name.
So mélange can be deliberate (which mine now is) or accidental (which
would appear to be your case Bob).
It adds meaning to "Its all good, its all good!"
Happy Cupping
On Sun, 2002-08-25 at 17:59, Ed Needham wrote:
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6) From: AlChemist John
Sometime around 05:57 8/24/02, Eric B. Stauffer typed:
I would agree that slowing down would help.  I do not recall, does the Mark 
I have a switch that allows just the fan to run?  If so, I would throw it 
on for a little every  30 seconds or so before 1st crack.  That is what I 
have done with a modified WBI and WBII (and my FR for that matter) to even 
out my roast and slow it down.  Also, I have noticed that if I am a little 
bit overloaded, my roasts start to get uneven.  I don't know the weight but 
it is around  1/2-2/3c by volume for the WB1.
I agree that some natural unevenness is nice for a cup, but I fully 
understand the desire to have a reproducibly consistent roast if I want 
it.  I hope this help.
John Nanci 
AlChemist at large
Roasting and Blending by Gestalt
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7) From: Ken Mary
I have used my Mark 1 only a few times, but have had this problem 
occasionally in other roasters. In my experience, it is normally caused by
overloading that results in poor mixing at the start, or by preheating the
Try starting with a cold roaster and make sure the beans are mixing by
themselves. Use less beans until you find the correct amount.
Do not forget that some bean origins will naturally roast unevenly.
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