When the mash has fully fermented it must clear. The mash will clear of itself if it is cooled down, it is just a question of waiting. To speed this process up a clearing agent is used, of the same type as is used for wine.
The mash is transferred to another fermentation vessel, leaving the yeast deposit. A clearing agent is added. Clearing is very rapid taking from 4 to 24 hours. Clearing can be speeded by cooling, placing the mash in a cool or cold location.
Mash that has been fermented using Turbo yeast usually clears quickly without the need to use a clearing agent. After clearing the, crystal clear mash is transferred over to the distilling apparatus with a syphon. The bottom deposit (lees) are then discarded.
Activated carbon is available in hundreds of different forms that are characterized by their absorption structure and special porous makeup. The carbon gets its characteristics from the method of manufacture and the basic raw material. The carbon absorbs impurities by virtue of many different effects. The carbon is very porous with a large surface area, usually 500-1200 square metres per gramme. The pores can be described as an enormous number of naturally occurring cracks or pores that have randomly fused together into a coherent structure. Carbon can be compared to small sponges where impurities fasten in the holes.
Absorption comprises an interaction of the exterior and interior surfaces that powers the active strength. Carbon has chemical, physical and electrostatic attributes.
Activated carbon can be made from crushed coal or made from various materials such as wood, coconut husk, peat or by-products of the oil industry. Ordinary coal is not active and contains many substances such as tar, etc. When coal is used as a fuel these substances give off heat. When activated carbon is made ordinary carbon is heated to a very high temperature of over 1000°C. The various substances are driven off as gas and leave the carbon. The process also charges the carbon electrically. What remains is a spongelike porosity. Certain substances in various raw materials are driven off at different temperatures, and using this effect the porosity can be controlled. In order to make further pores steam at 130° C is injected into the carbon. By selecting the raw material, temperature and form of treatment (steam, hydrogen superperoxide, etc.,) the appearance of the pores, the number of pores, (measured in square metres per gramme, usually being between 500 and 1 200) and the electric charge can be tailor made.
Raw materials differ in weight, thus coal, for example, weighs twice as much as peat, which for the same volume gives it double the price for the carbon. Certain materials contain a large amount of substances that are removed by steaming, thus giving a big absorption area. These pores are tailor made for the purpose (they are formed so that fusel oil, etc. fit exactly in the pores). In consequence there are only a small number of suitable forms of activated carbon for purifying alcohol. Apart from the pores formed so that the relevant impurities are trapped in them, the activated carbon is also electrically charged. Impurities fasten onto the surface of the carbon as though magnetically attracted. When filtering through a tube do not filter through twice, as the second time the impurities attracted to the outside of the particles will be removed.
Apart from the structure of the carbon, three other factors are significant: particle size, contact time and contact area. Refer to: Purifying with activated carbon.
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