Filter design can affect the smoking experience and even the taste of cigarettes
How are the components of a cigarette put together in manufacturing and how can design vary the taste and smoke yield?
The cellulose acetate tow in a filter is a web of fibres made from wood pulp. In manufacturing, the filter material arrives as a single long band of over 10,000 fibres pressed into large 750 kg bales.
In a filter maker, this band of compact fibres is mechanically stretched to open the fibres up, sprayed with a plasticizer to bind them together, wrapped with thin paper, cut, and fed into a cigarette-making machine.
Varying the taste and smoke yield
Once the taste has been determined, other design features can vary the strength of the taste, and can reduce the yields of various smoke components, as measured by a standardised machine method.
Filter design: The design of the filter can be varied, for example by making perforations, by changing its length or its density (by using more fibres), by the fineness of the fibres and by the type of material used. All these filter variations can affect the amount of filtration, and thus the taste, smoking experience and smoke yields as measured by a standardised machine method.
Charcoal is sometimes combined with the standard cellulose acetate, as its adsorption properties can reduce some of the gas components in smoke. It is usually used in a filter with two sections: a plain white cellulose acetate section at the mouth end and a section that has been sprinkled with charcoal. Because charcoal is mainly elemental carbon, these are sometimes called carbon filters.
Making small perforations in the filter is called filter ventilation, to reduce a cigarette’s yield and sensory strength. These dilute the smoke with air, leading to less smoke being produced in each puff. Filter ventilation is important in reducing smoke gases that are not trapped in the filter.
Paper: The paper around the tobacco rod and around the filtration zone can be adjusted. The porosity of the paper (the amount of air that can pass through it) will affect the yield, strength and taste of the cigarette. The more air that can pass through the paper, the more the smoke constituents passing through the cigarette are diluted, to make a lower yield, lighter tasting product.
Expanded tobacco: Another design feature to vary the taste, strength and delivery of smoke constituents is the use of expanded tobacco lamina, known as Dry Ice Expanded Tobacco (DIET). This is tobacco lamina that has been puffed-up and expanded.
As expanded tobacco takes up much more volume than ordinary tobacco lamina, less tobacco is needed to make the cigarette, resulting in a different taste and lower emissions, including of tar.
Putting it all together
In manufacturing, each brand has a specific tobacco recipe, a designated paper, filter, level of filter ventilation, tipping and graphic printing.
All the machinery is pre-set to ensure product consistency. The tobacco recipe is conveyed to a cigarette making machine, which wraps the tobacco at high speed in a high quality flax-fibre paper to form a continuous rod. This is then cut to the right length and joined with the filter, to produce the finished cigarette ready for packing.