Metal In Coffee

Metal In Coffee

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Yes it happens from time to time, fortunately not that often, but it only needs to get into someone’s coffee and they have the possibility of grinder damage. Sweeping with a metal detector is one option, but many are set to discriminate out long thin objects like nails!! There are a plethora of smaller hand held sensors on e-bay, but made in china and probably not that effective on very small metal objects. The real hand held security scanners are quite expensive, but again probably won't help you detect pins and staples within the coffee.

In general, most of the metal in coffee is going to be magnetic, your are less likely to find copper, aluminium or stainless steel. In the case of Copper and Aluminium, being quite soft possibly won't cause as much (if any) grinder burr damage as Stainless Steel. So weeding out all the magnetic objects, is going to solve a big part of any potential problem.

I had considered Ferritic Magnets, cheap, cheerful and a nice big hand sized block is around £8-9, this large magnet could be used to sweep the coffee, but does rely on remembering to do it and also doing it properly. I decided that this was all a bit too much hassle and prone to error. Instead I opted for small neodymium magnets these are extremely powerful for their size and if the correct type are sourced, fit nicely in the Cooling Tray exit chute of the Toper Cafemino. This means your beans are automatically magnetically swept each time you empty the cooling tray into a container, you can never forget!

I sourced the magnets from here and went for the neodymium rectangular block magnets, part number EP647, 10 magnets measuring 25mm x 10mm x 3mm, cost £9.05 inc delivery. These fit very nicely in the roaster exit chute as you can see from the pictures, and because they are magnetic, they just stick there under their own magnetism. They are also on so strongly, they won't ever fall off

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Of course, these magnets can also be stuck to any piece of steel and then passed manually through the roasted coffee, or embedded/stuck to the bottom of a tray in which coffee is then shaken. This makes the method relevant to the home roaster and not just to the exit chutes of small commercial roasters.