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Thread: screening for stones etc

  1. #1
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    screening for stones etc

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Howdy. Did my first batch of the gambella sundried the other day, and although I thought I screened for stones fairly carefully, I mustve missed this one when they were green, and Im guessing it was stained brown in the roaster by all the coffee oils. What with the different size beans and all, the damn thing looks exactly like a coffee bean. I found it by hearing all the cracks in my girlfriends whirlybird grinder (shh, its either my fresh roast in that, or preground when im over there) and seeing the chipped blades.

    Im guessing that had I just emptied it into my rocky hopper like I usually do at home, this would have been the death of the poor thing, or the burrs at least.

    Has anyone had any bad experiences with stones like this? Or have an efficient technique for screening or something? With another 9 batches of it, plus some even uglier looking beans I picked up elsewhere, Im afraid of killing my poor grinder :(

  2. #2
    Senior Member Dennis's Avatar
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    Re: screening for stones etc

    Dont worry too much Sam.

    Most of the grinders CSers use will easily cope with the occasional rock - nails are a different matter. ;)

  3. #3
    Senior Member Koffee_Kosmo's Avatar
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    Re: screening for stones etc

    Yea
    Andy emailed me back an answer to a question regarding rocks and glass
    He said much the same thing that Dennis said
    The grinders are much tougher than we think

    KK

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    Re: screening for stones etc

    The grinder must be tough of i am extremely lucky and/or totally blind.
    In all the roasts i have done, i have yet to find a stone. ;D

    Mal

  5. #5
    Senior Member Dennis's Avatar
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    Re: screening for stones etc

    You can usually hear them as they go through the grinder Mal - a kind of crunchy sound that you hope doesnt last too long. ;D

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    Senior Member Stan's Avatar
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    Re: screening for stones etc

    How often is foreign material found in the beans. I have yet to locate any or have I just been lucky. :-/

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    Re: screening for stones etc

    Weve got some Dominican republic San cristobal Bani at work and its a fair bit of work to get all the stones out before it goes into the roaster. I also found about a 100grams of corn in the bottom of a bag of colombian last week.

  8. #8
    Senior Member Dennis's Avatar
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    Re: screening for stones etc

    Quote Originally Posted by Stan link=1221875028/0#5 date=1221897458
    How often is foreign material found in the beans. *I have yet to locate any or have I just been lucky. *:-/
    Bit like the lottery Stan - there will always be one lucky winner!

    As mentioned earlier, its more prevalent with dry-processed beans. *Foreign materials tend either to float to the surface or sink to the bottom with washed varieties - though at the latter part of the process, these can also be spread out to dry on old concrete slabs, just as dry processed are. *Were not necessarily talking the same quality concrete slab youd find here either. *Usually find more stick-type foreign matter where machinery is used to harvest as opposed to gravel, where the beans are raked and turned on a slab.

    Large, commercial roasters will employ a destoner as a precaution, and most of the top-end grinders include a rare earth magnet strategically placed in the hopper. *You can do the latter too buy buying one and dangling it from the lid of the hopper, but I think its more the type of gift you would get for the snob who already has everything else.

    Make sense?

    EDIT: I think the farmers put the corn in for a bit of a laugh.

  9. #9
    Senior Member Stan's Avatar
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    Re: screening for stones etc

    I am wondering how a rare earth magnet stops stones from going through the grinder. *It they were high in iron I can understand but most stones are not affected magnetically? *Or am I uninformed. :-/

  10. #10
    TC
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    Re: screening for stones etc

    Quote Originally Posted by Stan link=1221875028/0#8 date=1221899927
    I am wondering how a rare earth magnet stops stones from going through the grinder. *It they were high in iron I can understand but most stones are not affected magnetically? *Or am I uninformed. :-/
    Nope- a magnet will only catch bits of metal which find their way into the bag

  11. #11
    Senior Member Stan's Avatar
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    Re: screening for stones etc

    It appears I will have to screen my raw beans more carefully. To date (touch wood) I havent had any issues.

  12. #12
    Senior Member Dennis's Avatar
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    Re: screening for stones etc

    And its the metal bits that are likely to do the damage!

    If it worries you, youll probably find it easier to pick out things like gravel after the roast as they tend to contrast better.

  13. #13
    Senior Member Stan's Avatar
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    Re: screening for stones etc

    I would imagine that after you have cooled the beans due to the agitation the rocks/stones would be at the bottom due to their specific gravity. As I have said, I havent found any at this stage. But if it is a common occurrence perhaps I should pay more attention to what is in the sieve.

  14. #14
    Senior Member Dennis's Avatar
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    Re: screening for stones etc

    Wouldst it be so Stan, but it aint.

    Some certainly make their way to the bottom - others can be remarkably light (probably why they grind so well) and are amidst the beans.

    All that makes it sound like there are lots to be found - not so. ;)

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    Re: screening for stones etc

    Check out this link about a coffee destoner by the guys over West. Sounds like exactly what youre after here...

    http://coffeesnobs.com.au/YaBB.pl?num=1214198025/

  16. #16
    Senior Member Stan's Avatar
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    Re: screening for stones etc

    Behmor Coffee Roaster
    Thanks, I saw that I will have a look at sourcing the necessary bits and pieces. To think before I joined CoffeeSnobs I just liked drinking coffee. How uninformed I was. :-/



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