Candles: Part X – Candle Manufacturing: Dyes

In the previous blog post, we looked into candle fragrances. Another additive that plays a significant role in the burning properties and health effects of the candle is the colouring ingredients.

When wax is obtained for use in making candles, it is usually white or cream in colour. A notable exception to that is unbleached beeswax candles, which have a natural golden hue.

The interest in adding dyes to candles is relatively recent. Original candles, such as those made from tallow, beeswax, seeds, and other materials were not usually coloured for aesthetics, though some colour may result depending on the materials being used. The primary factors that influenced the materials chosen for candles were smell and burning properties, such as the production of less smoke.

Candles now are not only chosen for a pleasant odour and cleaner burn, but for decoration. Sometimes, these decorative candles are never burned. When choosing a candle with a particular odour, the consumer may also expect the candle to possess a colour that reflects that the scent. For instance, if the candle has the scent of cinnamon, they may expect it to also be bronze in colour. Most colourants for candles are synthetic. New shades, hues, and formulas are introduced every year.

Unfortunately, as in the case of fragrances, colourant formulas are considered propriety and the manufacturers do not have to reveal the ingredients they use.

Colourants can come in a variety of forms, including liquids, gels, oils, wax chips, solids, powders, and pigments, and can come from a number of sources, including herbs, flowers, berries, nuts, roots, resins, beans, clays, oxides, ochers, metals, minerals, insect and animal extracts, and synthetic compounds. Because wax is insoluble in water, colourants that contain water or glycerine will not work. Food colouring is a type of water based colour that will not mix with wax.

Two main categories of colourants are dyes and pigments.

Dyes are the most common form of colourant in candles because they are easily combustible and dissolve in liquids or other substances. Depending on the composition, they may be water or oil soluble. They may come chip, block, liquid, or powder form.

Chip and block dyes are made of wax, which can include paraffin or vegetable based, with a pre-measured amount of dye.

Dye chips come in a wide variety of colours and are easy to use. You simply drop one into the wax at the beginning of the melting process. If using multiple chips, you may want to wait until the previous chip has dissolved before adding another one.

Blocks are more concentrated than chips and are best suited for colouring larger quantities of wax. They can be used for smaller quantities by shaving pieces off, but this makes it harder to measure and get consistent results.

Liquid dye is the most concentrated and only a few drops are needed. It is easier to measure, which helps in getting consistent results. The disadvantage to liquid dye is that it may have a strong, unpleasant odour that may affect the candle fragrance if a lot is used.

Powdered dye is extremely concentrated and provides the base for most other dyes. It comes in a limited range of colours, but can be blended to create more. This type of dye may need to be mixed with solvents or oils when used in wax to help with dispersion and prevent undissolved particles.

The intensity and colour of the dye will vary by manufacturer. Dyes used in soy wax will appear more pastel.

One of the most common colourants used in candles is aniline dyes. Aniline dyes are manufactured from the chemical aniline. Aniline is an artificially produced chemical that was first obtained in 1826 by the destructive distillation of indigo, but is now commonly derived from benzene, a toxic, volatile compound present in coal tar and petroleum. It may also be prepared from phenol and ammonia.

Aniline is used in the manufacture of: dyes and dye intermediates for fabric, leather, wood, food, and more; rubber processing chemicals; pharmaceutical products; photographic chemicals; isocyanates for the urethane industry; herbicides; fungicides; and diphenylamine for the rubber, petroleum, plastics, agricultural, explosives and chemical industries.

The chemical is toxic by inhalation of the vapour, absorption through skin, and ingestion, but the extent of its effect on health depend on the amount, type, and duration of the exposure. Significant exposure occurs when working with the chemical, and can result in the formation of methemoglobin, a form of hemoglobin (the protein in red blood cells that is responsible for transporting oxygen from our lungs to the cells in our body) that is not able to bind to oxygen. Some methemoglobin occurs naturally, but too much can result in insufficient delivery of oxygen.

Symptoms associated with aniline toxicity and increased methemoglobin formation include headache, fatigue, dizziness, irregular heart rhythm, and even loss of consciousness or death. Aniline can be irritating to the skin, eyes, and respiratory tract. Long-term exposure can affect the nervous system, cause liver damage, and and may cause the destruction of red blood cells.

Amounts of colourants in candles are said to be of minute quantities that have little to no affect on health, but without knowing the exact formula and concentration, there is no guarantee.

Pigments consist of very fine particles that do not dissolve. They can be made from natural sources or synthesized, and are categorized as organic or inorganic. Organic pigments are carbon-containing compounds that can be from insect, animal, or plant matter, such as herbs, spices, flowers, roots, and resins.

Inorganic pigments can include natural compounds such as natural iron oxide, bentonite mineral, natural micas, and natural zinc oxide; and synthetic compounds such as synthetic iron oxides, titanium dioxide, chromium oxide green, ultramarines, and synthetic micas. While natural pigments may not contain some of the harsh chemicals that synthetic pigments do, some of them may still be laced with dangerous components, such as heavy metals.

The pigments currently used as colouring agents for candles are usually man-made. Similar to fragrances, they may be nature identical. They may have the same chemical structure as minerals or other compounds found in the earth or in plants.

Pigments should only be used on the exterior of the candle, usually by dipping the candle in it. They do not burn well and may clog the candle wick and result in increased smoking or cause the wick to stop burning. Many people have used melted crayons to colour candles, but this is not recommended since it may contain pigments or other particles that may clog the wick.

There are many different types of pigment or dye compounds that are available. Most synthetic dyes or pigments are derived primarily from coal tars and petrochemicals, but it is nearly impossible to list all the ingredients that are used, particularly since manufacturers do not have to disclose formulas or ingredients.

Common colourants may also contain solvents, which can include carcinogens such as toluene, xylene, and benzene, though there are some that use vegetable based solvents and oils.

Conventional candle colourants are specially formulated so at not to interfere with the burning of the candle, but that doesn’t mean that they do not contain potentially hazardous compounds that could be released in the air during the combustion process when the candle is lit.

True all-natural candle colourants aren’t generally available to purchase. Most natural, organic and plant derived dyes are water soluble, which means they cannot be used in candles. You can create your own colours by infusing spices/herbs such as turmeric, paprika, beet, and plant leaves in oil (known as oil infusion).

One method of oil infusion involves melting wax in a kettle or double boiler and then dropping in a heat sealable tea bag or a coffee filter tied with string or a twist tie that is filled with herbs. Let the herbal bag steep on low heat for several hours, or until the colour of the herbs tint the wax, before removing. The coloured wax can be used as is to make a candle, or it can be blended into other waxes to provide some colour.

Spices added directly to hot wax may act more like a pigment. Mashed fruit, such as blackberries or blueberries, and dried and/or crushed flower petals may also be used to create colour. One should always use caution when adding substances directly to candle wax, since they have the potential of clogging the wick and preventing its ability to burn properly.

If making your own candles, be careful not to add too much colour. Too much colourant can clog the wick and affect overall scent. The type and amount of colourant you use depends on the size, shape, and type of wax of the candle. Also, be careful when handling colourants since they can stain surfaces, skin, clothing, and other material, and may cause allergic reactions in sensitive individuals.

Coloured candles may fade over time due to heat, light, fragrance and other agents in the candle.

Now that we have looked into the fragrance and colourant ingredients used and their effect on the candle, in the next blog post we’ll look into the final step in the manufacturing or candle making process: moulding, pressing/extrusion, or dipping.