Time of use (in 2007)
I'm using this roaster for some seven years now and roast a minimum of 800 grams weekly. Some years ago I bought a second one which I use in Holland now, the other one moved to my house in Italy. The roasters never let me down so far and it must have roasted some 200 Kg -i.e. 400 pounds. Some users report problems but I've never had any; knock on wood!
The price I payed for the recently bought one was EUR 99,00 -USD 120,00- which is a very good price for the thing although due to the low sales, prices have gone down some more recently that's why I bought a third one as a spare for EUR 80,00.
The roaster is well built and made of steel and bakelite, a very sturdy material. The glass cover fits very well and lets you see the progress when it is still clean. When roasting dry processed beans it gets dirty. The machine is archaic; no electronics or anything fancy. A fan motor, a heating element, a switch and a mechanical switching timer, that's all. A chaff collector captures nearly all chaff but some still swirls around. After the heating cycle, the cooling down cycle works perfect.
The design of the Imex looks good -for my taste- but the ergonomics are louzy. When you operate a roaster, you put the exhaust away from your face but the timer and the 'on' light-which you have to watch while roasting- is mounted on the same side. The designer obviously never used it himself.
The manual which comes with it is not very clear but mentions filling level against main voltage. No mention of ambient temperature though which is of much greater importance.
How it works.
Outside air is sucked in the bottom by the fan, then passes the heating element and the beans in the bean chamber followed by the chaff collector before being pushed out via a grid. Part of the air is -under the chaff collector- being sucked in again by the fan thus increasing the air temperature. Since the temperature inside the roasting chamber is not controlled bij any device, the user must control it himself by regulating the flow or changing the filling level, as explained later. The roasting temperature depends of: the ambient temperature -incoming air- and the resistance of the beans in the chamber and, only slightly, on the filling level of the chaff collector.
Since the roasting temperature depends on this it runs from 170 grams up to 185 grams depending on outside temperature and bean size as explained later. Some home roasters might find the capacity low but if you roast blends most of the time it's a very good capacity. For a blend of 3 origins, you end up with half a Kg. Bean size is important. If you roast large beans like Maragogype you use less coffee. I suggest some 155-160 grams where you use 170-175 of normal beans.
The best way to clean the inside and the glass cover, is with stainless steel pads. Don't use much water and dry the chamber very well afterwards to prevent shortage of the heating element.
How to work the thing?
As I explained, the roasting temperature depends on three things: outside temperature, bean resistance and used-air flow. Of course it also depends on the AC voltage. The manual speaks of the filling amount versus the AC voltage as the only temperature control. The lower the voltage, the more beans. This only works partly. If you fill it up with to much beans the rotation stops completely and you have to shake it yourself... If you follow the manual and have no primer experience with coffee roasting, you cannot get good results in countries where temperatures are moderate.
Why didn't they test it better at the factory?
Well they probably did but the outside temperature in Korea is different from that in London or Amsterdam and that's the problem. Maybe they tested it at summer high. It is still impossible to reach the right roasting temperature by increasing the filling amounts. Some users solve this problem by using a variac but the cost of a 1200 VA variac is quite high and the thing is big and heavy while the Imex is so elegant and small. Also turning up the voltage is a bit risky for the heating element.
The only other solution is using more used, heated, air. This is done by covering the grid of the exhaust for 25 to 50 percent with some aluminium foil of sheet-metal. I described the mod many years ago and it works fine for all users. I myself use two blinds; one for summer and one for winter -the larger one. Here's a picture of the mod:
As a starting point for the modification, I aimed for a 10 minutes roast up to the point of the second crack and an amount of 180 grams of beans at an ambient temperature of 18 degrees centigrade. After some expirimenting with aluminium foil the mod can be placed. I do not guarantee it will not damage your machine but it never did as far as I know.
If the beans do not move - and they don't in the first part of the roast and very little when the amount is over 150 grams - shake the machine gently while tilting it backwards. This way the darker beans come on top and the tilt prevents beans from exiting into the cahff collector.
After putting in the beans -regular size-, you have to use your senses since the machine has none. After the hardly distinguished first crack at some 5 to 7 minutes, the beans start to move a little more. At 8 to 9 minutes, beans start to coulour brownish and darker. At this point you can stop the roast at the colour of your liking. So use your eyes to stop the roast by turning the timer to the cooling cycle.
A little later beans start to go into second crack which you can hear. Also the tickling sound of the movement against the steel wall gets higher in pitch since the beans are getting lighter. After some time you can actually hear when the beans are ready for your purpose and stop the heater.
Now the moment comes that you smell a heavier, burning odour. Usually smoke comes out from under the lid. This is the point where the beans are getting black. Stop the roast immediatly at this point.
Swich off the machine at any point by rotating the timer or elongate the roast by rotating the timer in the other direction. The indication light lights up when the heating element is on. The knob must be turned quite far back to switch it on again.
Now with an archaic roaster and your own good senses you can accomplish a perfect roast. If you ask me 'Would I want a more sofisticated roaster?' I would not. I like the machine like all archaic things like Swiss watches, German camera's and old Land Rovers. Would I recommend it to others? Yes as long as the others have a real interest in roasting coffee and are prepared to learn. A pity none of my friends are.