While the art of candle making has been perfected over many centuries, technological advances around wicks have certainly modified the burn characteristics well beyond early times. Today the construct, composition, and geometry around wick design has allowed candle makers to fine tune burn efficiency and, in some cases, improve the safety of their luminary products.
Atkins & Pearce has been in the wick business for over 200 years, and during that time has produced billions of linear feet of wick material using countless varieties of materials, arrangements, and methods. Because of this experience and institutional knowledge, Atkins & Pearce is unlikely to encounter any current application or customer need that it has not already evaluated or serviced in the past, and for which it is not fully prepared and equipped to deliver today. Discussed below are some of the considerations that go into the process of fulfilling our customers’ needs with regard to wick design and construction.
Wicks consist of a combination of materials, treatments, and architecture that allow capillary action (wicking) to occur. Wicking is the process by which fuel is drawn up into the tip of the flame where it combusts. Many variables can affect the characteristics of capillary action and, therefore, the performance of a candle.
Wicks systems can be formed from non-woven or woven textiles which are braided, knitted, woven or nonwoven. Wicks can also be extruded from an emulsion of cellulosic materials. Indeed, any regularly porous material, including wood, bone, dried seaweed, bamboo or bamboo fiber, hair or fur, hide, or indeed almost any kind of dried plant or organic tissue can support wicking function. Further, inorganic porous materials, including stone, such as pumas, or wire mesh can be used to wick combustible materials resulting in continuous-burn candle functionality. Wicks can take any shape as well, including the familiar round cross section, but also rectangular or flat as in most oil lamp wicks.
The tightness of the construction will often effect the efficiency of the burn. Textile wicks dominate the candle market and are manufactured in a variety of geometries including but not limited to flat, round, or square shapes. The shape of the wick is dependent upon the method of manufacture. For example, extruded wicks can be prepared in any shape, which is simply a function of extruder die design. Materials can be twisted and bundled to produce multiple geometric designs and can be further employed in combination with other materials. The number of fiber bundles, the size (diameter), and the orientation or “lay” of the fibers contribute significantly to the fuel capacity of the wick. In addition, these variables will contribute to the stiffness or “stand” of the wick. Additionally, these variables provide curvature at the tip of the wick as it burns, which is an important consideration as it ensures complete combustion of the fuel and permits “self-trimming” of the wick to take place. Wick design parameters and self-trimming properties will minimize the formation of carbon deposits at the tip as well as reduce smoking and dripping.
While the construct and geometry of the wick play an essential role, composition of the wick media is equally important. Numerous materials such as organic, inorganic, cellulosic, non-cellulosic, and metals have been employed in wick technologies over the years. Cellulosic materials such as paper, wood and especially, cotton are by far the most common media. The combination of these materials can be used as lines, warps, cores, and jackets, to provide various physical attributes and burn performance. Wood wicks have become increasingly popular in the candle industry over the past decade. Both hard wood and soft wood wicks are available, however, soft wood has found favor because these wicks offer the appeal of a burning fire whereby they can crackle and pop during combustion. However, the intensity of the crackle can be influenced by the concentration of fragrance oils, quality of wax and dye types. Beyond cellulosic, extruded polymeric compositions have been identified as suitable for use as a wick media in select applications. Additionally, inorganic materials such as zinc or copper wire are often used as part of the wick composition to improve heat transfer down the wick, as well as to stiffen the wick.
As alluded to above, cotton is by far the most common media for wicks due to its widespread availability. Because of its molecular design, cotton can absorb up to two-thirds its weight in water. The ability of cotton wicks to absorb moisture renders them particularly amenable to aqueous treatments that can for example, enhance the fire retardancy of the wick, which is most common. Aqueous solutions of are typically employed for this affect. Other aqueous chemical treatments offer the ability to reduce afterglow when the flame is extinguished. The use of volatile citrate esters as chemical treatments has also been reported to alter the color of the flame. Other treatments can be used to impart color into the flame. Beyond those referenced here, there exists many different wick treatments which can be applied to stabilize the wick, catalytically enhance burn, protect the wick against acid degradation (i.e. stearic acid from triglyceride waxes), reduce carbon deposits, enhance brightness and many other special attributes.
Due to the diversity and complexity of the candle market there exists no universal wick. Dependent variables such as wax or fuel source, candle size, fragrances, dyes and other factors, require wick manufactures to design and produce hundreds of different wick types. Atkins and Pearce, through its Candle System Optimization, and backed by over 200 years of experience, can identify or design a customized wick solution for your candle needs.