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Thread: Coffee and stones

  1. #1
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    Coffee and stones

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Just wondering has anyone ever had a stone go through their grinder or is it just one of those things Im paranoid about?

    I can remember about 6 months ago I had a load of pre-roasted coffee that I found a stone in (luckily I had my old Russell Hobbs wizzy at that stage) and all it did was make a racket. I would imagine a burr grinder like the Rocky would be fairly cactus after putting a stone through it?

    Mick

  2. #2
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    Re: Coffee and stones

    Mick, you can get all sorts of material other than coffee in a bag of beans. When you buy, you are buying a share of a bag and all it contains. You have to be on the lookout for rocks and other matter that could potentially damage you and your hardware. There is at least one member who has had the unfortunate experience of grinder meeting rock. It does not happen very often but I have seen several small rocks and once a piece of glass in the Yemen Ismaili. Given that these are dry processes beans, it is not really surprising that they occassionally contain a few extras. Be alert!

    Cheers,

    Graeme

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    Re: Coffee and stones

    Ive had a rock come thru into the Mazzer. It was large enough to not get dragged into the burrs, just sat there making a racket.

    Ive picked a number of rocks out of Yemen Ismaili as well, and just last week I found a few small chips in a batch of Brazil Yellow Bourbon and one small bean-size rock in some Ethiopian Harrar.

    As Graeme says, its a good idea to pay attention.....

  4. #4
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    Re: Coffee and stones

    Coincidentally, I had the same experience.
    Just yesterday I heard a "terrible" noise coming from the mazzer...emptied out the beans and lo and behold a small stone!
    I too suspect the Yemen ..very small beans, getting to the end of my batch and probably would not have picked it up even if I was more careful (short of looking at every bean).
    This Yemen has been terribly overrated in my opinion, and now has only served to possibly have damaged my grinder burrs.

    So a lesson learned .... check those beans before grinding..!!

  5. #5
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    Re: Coffee and stones

    The Commercial roaster have stone extracters or dump onto a large revolving tray. I guess this would help spot any stones.

    The organic stuff is incinerated in the roasting process.

    Rich

  6. #6
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    Re: Coffee and stones

    For a commercial roaster with a 20kg batch, I suspect dumping the beans into a revolving tray wont do much for spotting rocks ;) Lucky that my sweet spot on roast size is 800gm, much easier to inspect manually.

    The ismaili is only one of many beans that has additional "contents" of the raw bags - but in my opinion there arent many as-nice or nicer coffees (YMMV). Were all individuals (luckily!) with different tastes and likes/dislikes.

    It seems to me that *any* bean roasted at home needs looking through - some you can get away with a quick scan (typically wet processed, as long as the plant has a destoner), others need more rigour (dry processed).

    I tend to do two inspections (as I know I am not likely to get every single rock first time, and practical experience has shown this)
    *when Im cooling the beans in my wire mesh basket, Ill shake them from the basket to the lid of the basket, and shake small quantities around in the lid. Rocks tend to gravitate to the edge.
    *when Im bagging the roasted beans from the mesh basket, Ill shake the beans around then scrape the top layer into the bag, then once Im near the end Ill look with more detail at whats left.

    I think I have been lucky with the stones that have gone into/thru the mazzer. I suspect (but dont know for sure) that Ive had small granite-like chips go in and thru mazzer, but the only large rock that made it into the hopper didnt make it into the burrs. Touch wood.

  7. #7
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    Re: Coffee and stones

    I have experienced stones in the grinder attched to the nepolitana 11. It made a hell of a noise and cracked the plastic housing that allows you to change the grind. This is now unusable or changes itself. Unfortunately i didnt even buy the beans they were given as a sample!!

  8. #8
    CoffeeSnobs Owner Andy's Avatar
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    Re: Coffee and stones

    a sample of what not to put in your coffee? * >:(

    I have found stones in the green beans before, some fair sized ones and even a flat lump of concrete the size of 10 cents but none have made (that Ive noticed) to the grinder yet.

    The small ones I would lose in the roasting process (fall through the basket) but the thought of bean sized stones scares me!

  9. #9
    Super Moderator Javaphile's Avatar
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    Re: Coffee and stones

    Quote Originally Posted by Andy Freeman link=1102078046/0#7 date=1112714593
    ...the thought of bean sized stones scares me!
    You and me both Andy! So far Ive done 154 roasts and have been lucky enough that no stone has made it into the grinder. Too date Ive only found 2 stones in any of my green beans. Both came in bags from the same supplier, one whom I will never use again due to the poor quality of the beans (I got 2 pounds each of 5 different beans from this supplier and they all smelled of nothing but burlap). The thought of getting a stone in my grinder and shredding the burrs sends shivers up my spine.

    Java "No stones allowed!" phile

  10. #10
    Senior Member fatboy_1999's Avatar
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    Re: Coffee and stones

    So far - no stones found in my beans - no stones heard in my grinder.
    After I roast, I dump the beans into a sieve with a fan underneath. I stir with a wooden spoon and have a look for any foreign objects.
    So far, so good. :)

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    Re: Coffee and stones

    We went through a heap of Yemen last year and the stones we collected from 2.5kg was about 1.5 table spoons.. all the size of the beans and smaller...

    some stone are well camoflaged as well.....

    FB

  12. #12
    CoffeeSnobs Owner Andy's Avatar
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    Re: Coffee and stones

    You could start filling a fish-tank with that lot.

    I wonder if your yemen was from the end of the bag.... I have an unproved theory that the stones should work their way down a bag...

    Most of a bags life is spent getting dragged by its "ears" and heavy stuff should move to the bottom of the bag and I guess sticks, grass etc should move to the top.

    If that is true, then I should look at hand sorting the last 5-10kg in a bag.

    ...or just remember to take mine from the middle! ;)


  13. #13
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    Re: Coffee and stones

    Nice theory about the stones. *I suspected that it *should* work like that as well, but I dont think that translates well in practical terms, from my experience. *

    My Ismaili is now in a loose calico bag, has also been in the original plastic bags as well in varying degrees of fullness, being transported up and down the stairs from the gold vault in the basement (well OK, the bean storage box in the garage). So plenty of shaking it up at my place too, not just in bag transport.

    I have even made sure I was taking only beans from the top to roast.

    I still found/find rocks. *To my totally non-scientific view Id describe them as angular granite chips of a light colour (even after roasting, which makes them easier to spot). And as FB alluded to above, it equated to a couple of tablespoons worth.

    Its not just the Ismaili. Ive had rocks in others as well - Brazil Yellow Bourbon plus many others. Theyve all been a bit different, and the ones that worry me more than the ismaili "granite" was the Brazil one - it was dark in colour to start, rounded not angular, and very much bean shaped and sized..... quite a tough one to find.

    Im happy though, got to expect this at times, so I always make sure I carefully hand-sort the beans after roasting and before packing. (hmm, mental note... in a 5kg batch, how the heck will I cope!!??!!)

    The only rock thats been in the mazzer was one from coffee I didnt roast (eh Fatboy :))

  14. #14
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    Re: Coffee and stones

    Roasting in a collander that is in a bowl, I find that some small stones go through the bowl underneath. At the end of the roast when I take the collander away there is lots of husk/chaff/silverskin? and occasionally some small stones. Ive never had one end up in the grinder... yet :-/

    Did somebody say Ismali? Has the Yemen Ismali been sent out?

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    Re: Coffee and stones

    Quote Originally Posted by sharkboy link=1102078046/0#13 date=1112886958
    Did somebody say Ismali? Has the Yemen Ismali been sent out?
    Sharky, it wont be in the country for several weeks yet and it definitely wont be going anywhere until it has been billed and paid for. All of the invoices for this were withdrawn. Just a case of waiting, waiting!

    Cheers,

    Graeme

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    Re: Coffee and stones


    I assume that a grinder manufacturers warranty is void if there are stones in the roasted beans?

  17. #17
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    Re: Coffee and stones

    Quote Originally Posted by tempestv8 link=1102078046/15#15 date=1176784385
    I assume that a grinder manufacturers warranty is void if there are stones in the roasted beans?
    OHHH Yeah....

    That would be classed as user abuse of the grinder... (and burrs are consumable items in any case - they will wear out eventually)....

    Manufacturers wont repair "stoned" grinders..... any more than car insurance companies will pay for damage when the driver is "stoned".... ;) ;D ;D ;D ;D ;D ;D

    User beware!!!

  18. #18
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    Re: Coffee and stones

    yeah...just keep a look out for DP beans like Ethiopia Harrar.



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