Activated carbon is more effective if high layers of granules are used. Fill a tube with granulated carbon. Normally a 1.5-meter-long tube with a 40-mm diameter is used. Filtration should be as slow as possible, without actually being blocked or stopped. The alcohol must flow through the carbon granules if the purification is to be as effective as possible. Make sure no alcohol bypasses the carbon, and make sure the tube is free from air.
Stir with a large spoon and allow the carbon to sink to the bottom of the saucepan before discarding the surplus water. Repeat this process 4-5 times so that all soluble substances in the carbon pores are washed out and it is saturated with water.