I cook regularly on a wood stove. Lately it occurred to me that I could also dump a sealed container into the flames to make activated carbon ... which I did. To test the carbon I dumped some iodine to colour the water - then tossed in a lump of the charcoal (crushed).

After a while the water was clear - which is perfectly fine. The trouble is, a layer of charcoal 'scum' formed on top of the water. I can get rid of the scum by passing the water through a filter - perhaps sand, or even fine cloth.

Is there a way to prevent the charcoal from carrying impurities that form the scum in the first place?


Filter carbon needs to be packed and prewashed to remove fine dust. "Crushing it and dropping it in" is fine if you are an old sailor on an old ship burning some ship's bread to drop into the nasty cask of fresh water - not so much if you want the water to be crystal-clear.

  • Additionally, if you didn't want to resort to prewashing/packing; maybe a better question would be how to siphon off the top layer entirely. My mind thinks of gravy making. Only take off what you want! Mar 12 '15 at 20:00

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