HomeRoast Digest

Topic: Radiant roaster: project failure (18 msgs / 489 lines)
1) From: Scott Marquardt
http://scott.marquardt.googlepages.com/radiantcoffeeroastingScroll to end.

2) From: James House
Don't give up.  Remember, we have velcro, corn flakes, and electricity
because of people like you.  :)
On 5/3/06, Scott Marquardt  wrote:

3) From: Myron J
Scott wrote vis a vis http://scott.marquardt.googlepages.com/radiantcoffeeroasting<Snip>
I say
Do NOT scroll to the End..
READ IT to the END!
OMG..Bummer is not the word.
I was hoping you were patenting the idea..this looked so good.
But remember...the Path..there is glory in the path taken!
Myron Joshua
Kibbutz Kfar Etzion
+972-(0)2-9935 178

4) From: Scott Marquardt
I think the only hope for direct IR -- and something perhaps worth trying -=
is in a fluid bed. But even then, what reason there is for hope is somethin=
potentially of consequence for roast chemistry -- "micro-exotherming," as
this amateur is calling it. Bah. This is a tough one to think about.   :-\
On 5/3/06, James House  wrote:

5) From: Alchemist John
I wonder if simply increasing your mix rate would help.  Don't give 
them a chance to go uneven.  Could also be that the whole roast needs 
to be slowed down to allow the laggers to catch up.
At 05:09 5/3/2006, you wrote:
John Nanci
AlChemist at large
Zen Roasting , Blending & Espresso pulling by Gestalthttp://www.chocolatealchemy.com/

6) From: Aaron
ditto on that dont give it up yet scott.  I cant help but thinking that 
if there was a way to close off the opening while roasting it'd help 
keep the heat in, use a lot less watts, and possibly help roast the 
beans better.  maybe a circle of metal with a hole cut in it for the 
cord to go through.  Maybe leave the chaff in, act as a buffer, and just 
be rid of it at the end when you cool them all down, you can blow it all 
out then.

7) From: Brian Kamnetz
I'm wondering whether your "bad" results (uneven roast) may not
sometimes be a good thing, depending on goal. There has been some
discussion on this list about the desirability of roasting several
batches of the same variety to varying points, then blending them
post-roast for a fuller range of flavor. It seems that with some
varieties your roaster would save some steps on the way to this
desired result.
On 5/3/06, Scott Marquardt  wrote:

8) From: Scott Marquardt
Right; I do that sometimes.
A couple things. First, a Harrar I roasted last night freaked me out this
morning. It came out inconsistent -- but Harrars often do. It was moreso. S=
I picked out the 20 or so very light beans, went to bed, and made some this
morning, unrested (the beans I mean -- I slept well.  ;-)
It was the best I've ever roasted this Harrar.   :-\
Talk about freaking me out.
The other thing -- my concern is that this roasting method exaggerates
differences among the charge beans. With a homogenous roast, this thing doe=
fine -- so actually with a lot of Tom's beans the thing works fine. But I
don't always buy from Tom, and I sometimes buy beans that cup well but are
lower grade for various reasons, often including size non-conformity which
will be vulnerable to this problem with exaggeration of the differences --
amplification of differences -- in the system.
OK, I won't give up quite yet. I have two more lamps, but if I don't find a
solid raison d'etre for this kind of roaster by the time I burn through the
third one, I'll put it on a shelf -- with due honors. This thing is fun.
Although the moths trying to fly into the thing STILL drive me nuts.
Thanks, y'all, for the encouragement. Fun to have new stuff dragging me int=
itself, and folks behind urging me on.   :-)
On 5/3/06, Brian Kamnetz  wrote:

9) From: Obrien, Haskell W.
This is a multi-part message in MIME format.
My guess is that the heavier beans are sitting furthest away from the
heat source.
The ones that have moved further into the roast become lighter as they
You may be successful if you modify your stirring vanes or make major
modifications and move the heat source to the outside of the roast
Just my opinion lobbed across the electrons.
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Scott
Sent: Wednesday, May 03, 2006 1:13 AM
To: homeroast
Subject: +Radiant roaster: project failure
Scroll to end.

10) From: Jim Mitchell
This is a multi-part message in MIME format.
Scott -
Just as I was about to go to sleep last night, I was sort of gently =
cogitating on your device and had a 'Kekule Moment' - Friedrich Kekule =
was the chemist who essentially jump-started organic chemistry as we =
know it, when he envisioned a chain of carbon atoms looping back on =
itself and, like a snake biting its own tail, forming a circle - thus =
discovering the Indole Ring - and why I don't believe that I.G. Farben =
would be interested, there may be a way out of your dilemma.
What I 'saw' in my mind's eye, is that you've got the heat source =
'backwards' - it wants to be at the bottom of the chamber, not the top - =
which should create convection currents inside the drum and more evenly =
distribute both the lamp's heat and the re-radiated heat from the beans. =
It's also currently a 'point source' and I wonder if simply diffusing it =
would counteract the bean-char issue?
Bottom placement raises other issues - like how to keep the beans away =
from the scorching-hot lamp - I think there may be several interesting =
One would be to use an Automotive Halogen bulb which comes already =
encased in quartz-glass envelope, I believe that Chrysler uses this =
style - these bulbs have the added advantage of also including a =
diffuser, which would further spread out the heat
The other would be to use a tubular Halogen element, encase it in a =
Borosilicate glass rod, and run it down the center of the drum. This =
would have the effect of evenly heating the entire bean mass as it =
rotated around the tube, and should promote even roasting.

11) From: Scott Marquardt
Right. Good remarks. There's a LOT of fascinating configurations for
placement and style of heater; I also like the ceramic heaters. But it's th=
remarks about re-radiated heat that interest me most. If a radiative roaste=
is to succeed GIVEN the problem I found (I'm sure I'm not the first), the
hottest beans that are darkening most need to have their momentum reduced.
However, this means they'll exotherm -- not chemically, but I mean they'll
give up heat they've already gained.
Isn't that a problem? Isn't that what's important to AVOID? If that's true,
then the hottest beans in the batch will end up suffering in their
chemistry, whereas the lighter late-comers to the party will come along jus=
On 5/3/06, Jim Mitchell  wrote:

12) From: Scott Marquardt
It's a fair guess, but no -- these suckers are agitating amazingly. I love
the 3-D action -- the vertical turnover of a drum, plus a horizontal axis o=
rotation caused by my vane dihedral (I don't know what the heck to call som=
of these geometries ;-) and the conical contours of the flask. It's like a
perfect design -- so I guess I should thank whoever designed it to hold
brewed coffee for their foresight.   ;-)
- Scott
On 5/3/06, Obrien, Haskell W.  wrote:

13) From: Steven Ban
avoid this problem, I'm all ears. But I'm skeptical. This is a real
system-breaker! Some kind of radiation that's entirely agnostic to the
bean darkness would do the trick, but that ain't infrared.
I think your problem is that you are not using the correct type of 
infrared.  You are using a short wave IR type bulb that is more suited 
for lighting than heating.  You need to be using a medium wave IR source 
that emits waves that do an excellent job of heating organic materials. 
  I have been roasting with quartz tubes for sometime now with great 
success.  I have a couple of small commercial roasters (1 kilo capacity) 
that were built using medium wave quartz tubes.
I currently use tubes manufactured by Watlow but I just discovered a 
company that makes a faster tube that I will be checking out called 
Soneko.  They make a medium wave “Twin Tube” that might work with your 
setup.  I have no idea what the Soneko lamps go for but a 12 inch Watlow 
tube that I have to special order is about $30.
I hope this helps.  I don’t think your project is a failure it just 
needs a little more tweaking.
Steve Ban
Scott Marquardt wrote:

14) From: Michael Dhabolt
needs a little more tweaking.<
Now this is where this list shines.  Great information and input.
Mike (just plain)

15) From: Scott Marquardt
Yeah, no kidding.
In general, are the longer wavelength IRs less reflective?
Thanks Steve.
On 5/6/06, Michael Dhabolt  wrote:

16) From: Steven Ban
Scott Marquardt wrote:
 > In general, are the longer wavelength IRs less reflective?
To my understanding you need to match the IR wavelength to the material 
you are heating.  A wavelength too short will reflect off and a 
wavelength too long will transmit through without heating the material. 
  That is why you need to match your wavelength with your material.
Now since you are mostly heating the water in the beans I think you will 
want to match your wavelength to heat water.  I think water has a strong 
IR absorption (when a wavelength is transformed to heat) with a 
wavelength of 2.5 to 6 microns.  The Watlow lamps that I’m using right 
now are rated at a peak energy wavelength of 2.5 microns.  The lamp you 
are using now must have a wavelength of less than 0.8 microns (0.39 to 
0.78 microns produces visible light).

17) From: Scott Marquardt
Holy cow. If that's true, then . . .
Good grief. I better dust off my favorites folder and contact that Chinese
guy with the new carbon quartz lamps. Almost no light and lots of heat.
On 5/7/06, Steven Ban  wrote:

18) From: raymanowen
How about the Fullerite -ene? molecule which is C80 and describes a geodesi=
sphere shape. There are molecules much larger than C80. I was happy to hear
about this over the dinner table from my Celtic Critic.
How does forensic pathology apply to EE? Never found out...
Cheers -RayO, aka Opa!
Got Grinder?

HomeRoast Digest