Wicks

How does candle's wicks made???

Wick types

The candle wick influences how the candle burns. Important characteristics of the wick include diameter, stiffness, fire-resistance, and tethering. The type of wax used in a candle, as well as the candle's size, shape, color and fragrance materials all impact wick choice. Candle wicks are normally made out of braided cotton. Wicks are sometimes braided flat, so that as they burn they also curl back into the flame, thus making them self-consuming. Approximately 80 percent of the wicks manufactured in the United States are made of all-cotton or cotton-paper combinations. In tealights the wick is tethered to a piece of metal to stop it from floating to the top of the molten wax and burning before the wax does. Candles designed to float in water require not only a tether for the wick, but also a seal on the bottom of the candle to prevent the wick from wicking water and extinguishing the flame. Wicks can be made of material other than string or cord, such as wood, although they are rare. The cotton of tampons can be used as wicks for oil lamps in wilderness survival situations. Fine wire (such as copper) can be included in the wick. This provides two advantages: it makes the wick more rigid, letting it stand further out of the liquid wax, and it conducts heat downward, melting the wax more readily. The latter is particularly important in candles made of harder wax. Stiffeners were once made of lead, but these have been banned in the U.S. for several due to concerns about lead poisoning. Other core stiffeners, such as paper and synthetic fibers, may also be used. 

Erm........What cotton is?

Cotton fibers use as the wicks of the candle. The chemical composition of cotton fiber consists of ninety-five percent cellulose, one point three percent protein, one point two percent ash, point six percent wax, point three percent sugar, and .8 percent organic acids, and other chemical compounds that make up three point one percent . The non-cellulose chemicals of cotton are usually located in the cuticle of the fiber. The components of cotton are shown as below:

 

95%	Cellulose (C6H10O5)n
6-8%	Water
1.6%	Waxes and fats
1.3%	Proteins
8%	Organic acids
1.2%	Ash

The non-cellulose chemicals of cotton consist of protein, ash, wax, sugar and organic acids. Cotton wax is found on the outer surface of the fiber. The more wax found on cotton the greater the surface area of cotton there is; finer cotton generally has more cotton wax. Cotton wax is primarily long chains of fatty acids and alcohols. The cotton wax serves as a protective barrier for the cotton fiber. Sugar makes up point three percent of the cotton fiber, the sugar comes from two sources plant sugar and sugar from insects. The plant sugars occur from the growth process of the cotton plant . The plant sugars consist of monosaccharide, glucose and fructose. The insect sugars are mainly for whiteflies, the insect sugars can cause stickiness, which can lead to problems in the textile mills. Organic acids are found in the cotton fiber as metabolic residues. They are made up of malic acid and citric acid.The non-cellulose chemicals of cotton are removed by using selective solvents. Some of these solvents include: hexane, chloroform, sodium hydroxide solutions, non-polar solvents, hot ethanol, and plain water. After removing all the non cellulose chemicals, the cotton fiber is approximately ninety-nine percent cellulose.

Cotton fibers and its chemical structure

The chemical composition of cotton, when is about 94 percent cellulose; in finished fabrics is it 99 percent cellulose. Cotton contains carbon, hydrogen, and oxygen with reactive hydroxyl groups. Glucose is the basic unit of the cellulose molecule. Cotton may have as many as 10,000 glucose monomers per molecule. The molecular chains are arranged in long spiral linear chains within the fiber. The strength of a fiber is directly related to chain length. The chemical structure of cotton are shown as below.

Hydrogen bonding occurs between cellulose chains in a cotton fiber. There are three hydroxyl groups that protrude from the ring formed by one oxygen and five carbon atoms. These groups are polar meaning the electrons surrounding the atoms are not evenly distributed. The hydrogen atoms of the hydroxyl group are attracted to many of the oxygen atoms of the cellulose. This attraction is called hydrogen bonding. The bonding of hydrogen's within the ordered regions of the fibrils causes the molecules to draw closer to each other which increases the strength of the fiber. Hydrogen bonding also aids in moisture absorption. Cotton ranks among the most absorbent fibers because of Hydrogen bonding which contributes to cotton's comfort. The chemical reactivity of cellulose is related to the hydroxyl groups of the glucose unit. Moisture, dyes, and many finishes cause these groups to readily react. Chemicals like chlorine bleaches attack the oxygen atom between or within the two ring units breaking the molecular chain of the cellulose.

The hydroxyl groups (-OH) of cellulose can be partially or fully reacted with various reagents to afford derivatives with useful properties like mainly cellulose esters. The organic acid that made up the cotton are used to react with the cellulose.

Cellulose ester	Reagent	Example	Reagent	Group R
Organic esters	Organic acids	Cellulose acetate	Acetic acid and acetic anhydride	H or -(C=O)CH3
		Cellulose triacetate	Acetic acid and acetic anhydride	-(C=O)CH3
		Cellulose propionate	Propanoic acid	H or -(C=O)CH2CH3
		Cellulose acetate propionate	Acetic acid and propanoic acid	H or -(C=O)CH3 or -(C=O)CH2CH3
		Cellulose acetate butyrate	Acetic acid and butyric acid	H or -(C=O)CH3 or -(C=O)CH2CH2CH3

Improvement

The burning qualities of a candle can be improved if arranges it so that a helically braided wick will  bend over to the side in the flame after it reaches a certain length, causing the tip of the wick to project into the hottest part of the flame. Then, as it burns, a kind of “automatic wick trimming” will take place. Further improvement is achieved by impregnating the wick with an aqueous solution of ammonium salts, boric acid, and phosphates.

1.Ammonium salts

- prevent a wick from burning up too rapidly

-Ammonium cation is found in a variety of salts such as ammonium carbonate, ammonium chloride, and ammonium nitrate. Most simple ammonium salts are very soluble in water.

2.Boric acid and phosphates

-produce a molten bead at the end of the wick, which in turn keeps pieces of ash from falling into the pool of wax, at the same time avoiding afterglow at the wick end when the flame is extinguished.

-Boric acid (H3PO4) -also called hydrogen borate, boracic acid, orthoboric acid and acidum boricum. It exists in the form of colorless crystals or a white powder that dissolves in water. When occurring as a mineral, it is calledsassolite.