Pitch oil was extracted as follows:
Pine wood with a high resin content, especially 'kean' (pine wood), was chopped up and piled on the stone and covered with earth, blacksmith's tinder and the like, as in a charcoal pile.
After the fire was lit, the pitch smear flowed down the grooves of the stone and through a hole or a wider channel in the stone into a container placed underneath; when this was full, the watery top layer was skimmed off and the rest was stored in cans or small barrels.
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