Wax manufacturing

The different types of wax are usually divided into three main groups:

1. Mineral waxes, or fossil-based waxes, make up most of the world market and are sourced from non-renewable raw materials like coal or crude oil.

• Paraffin wax, or petroleum wax is one of the most common types of wax and is popular for its purity and consistency. This soft colourless wax is derived from petroleum, coal or oil shale and applications include candles, cosmetics, paper coating, paint, lubrication and electrical insulation. 
• Microcrystalline wax is produced by de-oiling petroleum as part of the refining process and is generally darker, more elastic and tackier than paraffin wax. Uses include candles, adhesives and cosmetics, and to reduce friction in sports such as ice hockey and snowboarding. When combined with paraffin wax, it is also widely used in the manufacture of plastic, rubber and tires.
• Montan wax, or lignite wax, is a hard wax extracted from lignite (brown coal) and peat. Like carnauba wax and beeswax, it helps provide scuff resistance, water repellence and a high gloss finish, but montan wax is less expensive. Around a third of all montan wax produced is used in car polish. It is also used in polishes for shoes and musical instruments, paints and as a lubricant for molding paper and plastics.
• Peat wax is a dark substance extracted as a by-product of peat tar production. It has very similar properties and uses as montan wax.

2. Synthetic waxes are artificially created from materials such as natural gas and ethylene.

• Fischer-Tropsch wax is made from natural gas using a number of chemical reactions known as the Fischer-Tropsch process. It tends to have a low viscosity and is used to apply a matt, scratch-resistant surface. It is often used to make lubricants, printing inks and varnishes.
• Polyolefin wax is a hard wax and can include polyethylene wax, polypropylene wax and polyamide wax. It is commonly used as an additive to modify the thickness and viscosity of liquids, creams and other waxes.
• Hydroxylated wax dissolves in water and is often used to build temporary support structures for modelling, casting or 3D printing.
• UV curable wax is applied as a liquid and solidifies via exposure to UV light. It is used in some slip-resistant coating and has a number of modelling and 3D printing applications.
• Polyethylene (PE) wax is thermally stable, chemically resistant and dense. The primary use of PE wax is as a colorant for plastics. It can also be found in crayons, paints, inks and as a mold release agent.

3. Natural waxes, or bio-based waxes, are harvested from plants and animals. They comprise a small but rapidly growing share of the market as manufacturers, retailers and consumers increasingly opt for more environmentally friendly materials and products.

• Beeswax is produced in the glands of honeybees and is used in a vast range of applications, from candle making and cosmetics, to polishes and food additives. 
• Lanolin, or wool wax, is secreted by the sebaceous glands of wool-bearing animals, predominantly sheep. It has a texture similar to grease, is water repellent and has hydrating properties when applied to skin. Lanolin is found in cosmetics and healthcare, as well as various lubricants, rust-prevention coatings and polishes.
• Soy wax comes from converting liquid soybean oil into a solid or semi-solid fat (hydrogenation). It is predominantly used to make candles as a biodegradable alternative to paraffin wax. Soy wax is softer and has a lower melting point than traditional waxes so candles made from it are typically held inside a container.
• Candelilla wax is a hard, brittle wax extracted from the leaves of Candelilla bushes found in the United States and Mexico. It is used as an alternative to carnauba wax and beeswax, and can be found in some varnishes and cosmetics such as lip balms and lotions. Its biggest use is as a binder for chewing gums.
• Carnauba wax, or Brazil / palm wax, is extracted from the leaves of the carnauba palm native to Brazil. The wax is hypoallergenic, moisturising and creates a glossy finish, making it ideal for use in cosmetics and polishes. It is also used as a mold release agent for manufacturing fibre-reinforced plastics and, when combined with beeswax, a waterproof coating for leather products.

The techniques used to produce a wax depends on the raw ingredients and the volume being manufactured. The processes used in the production of beeswax and paraffin wax demonstrate the most common:

Beeswax

Beeswax is secreted from glands in the abdomen of honeybees. The bees chew the wax to give it a firmer texture then use it as a building material to form a honeycomb.

1. A beekeeper removes the wax from the hive, usually in the form of plugs (cappings) which bees use to seal each honeycomb cell, or from an old comb.
2. This material is then placed in a centrifuge to remove any remaining honey.
3. Hot water is added to separate out any large impurities. 
4. Smaller impurities are removed by passing the wax through various filters under pressure.
5. In most cases, the wax is then bleached until completely white. However, some manufacturers prefer to use gentler cleaning solutions so the wax retains its honey color and scent.
6. The wax is then sold in either liquid or solid form – usually pellets, bars flakes.

Paraffin wax 

Paraffin waxes are refined from crude oil, which can contain anywhere from 2% to 30% solid wax depending on its quality and origin.

1. Crude oil is a mixture containing many different hydrocarbons that need to be separated. This is done through fractional distillation, a process which takes advantage of the different boiling points of compounds. 
2. The wax resides within several of the oils produced by the distillation. To extract it, the oil is mixed with a variety of solvents.
3. This mixture is warmed until it forms a single liquid of uniform appearance.
4. It is then cooled in a chiller designed to scrape out any solids as they form. The solvent and oil remain in the chiller and the wax is collected in crystal form.
5. The wax crystals pass through a vacuum filtration system and washed with solvent to remove any remaining oil.
6. The wax is then sold in either liquid or solid form, usually pellets, bars flakes.

Following these steps, the wax will likely undergo further processing depending on its intended application. This may include adding or removing colors and scents, or blending with other waxes and additives to alter its properties.

The three most widely used wax manufacturing techniques are:

• Lost wax casting, or investment / precision casting is a very old technique used to produce intricate metal shapes that would be difficult, expensive or impossible to machine in other ways. The object is first sculpted out of a soft material such as clay or wax. A mold of this sculpture is made containing a soft inner mold which is the exact negative image of the original model and a hard outer shell. Molten wax is then poured into the mold, either enough to fill it completely or to coat the inner surfaces.

Once hardened, this wax version is removed from the mold and coated in several layers of a fire-proof, stucco-like material. Upon drying, it is placed upside down in a kiln where the wax melts and runs away to leave a void the exact shape and size of the original object. Molten metal is poured into this void and once cooled, the stucco shell is sand-blasted or hammered away to reveal a rough-casting which can then be ground, filed and polished.

• Injection molding largely follows the same process used for many types of plastic. Wax injection molding is typically used to make models for lost wax casting, whereas plastic injection molding is used to produce finished goods. Wax pellets are melted and hydraulically injected into a temperature-controlled mold cavity. The mold is clamped and cooled in order for the wax to harden into its final shape and can then be removed.

• Nano-emulsification is a method that allows non-water-soluble waxes to mix with water-based ingredients. It is used for a variety of wax applications including in food, pharmaceuticals, paint, polishes and protective coatings. It is also used to add water-based scents and colors to solid wax products like candles.

A wax nano-emulsion is made by exposing the wax to specific chemicals or ultrasonic sound waves. This breaks it into microscopic particles that are small enough to mix with water and form smooth, stable fluids or gels. 

There are several reasons why wax is still routinely used throughout the world:

1. Versatility – There are many different types of waxes, each with their own unique properties and characteristics. 
2. Wax blends – If one wax does not possess the necessary strengths, it can be easily improved by combining it with other waxes, additives, colorants or scents. 
3. Manufacturability – Wax is easy to work with and can be sculpted into a wide variety of shapes and sizes. It can also be prepared for use in a few simple steps without the need for expensive, specialist equipment.
4. Solid structure – Most waxes have a low melting point, but they remain as malleable solids at room temperature. Some even develop a smooth surface that makes them well-suited to being used as polish or lubrication. 
5. Water repellant – When applied thickly, most waxes form a waterproof surface which can be used to protect the surface of materials or added to paints and adhesives.

Wax also has several downsides:

1. Durability – Wax has a long history of being used as a waterproof, protective surface. However, modern alternatives are now cheaper to manufacture and provide harder more durable protection.
2. Soot – When burnt, wax produces a fine sooty residue. In some cases, particularly fossil-based waxes, this can release small amounts of chemical toxins.
3. Suitability for casting large objects – While still routinely employed, the poor structural integrity of the material means lost wax casting is not appropriate for producing large, bulky objects. 
4. Non-renewable sources – Waxes derived from non-renewable raw materials such as coal, crude oil or natural gas make up the largest portion of all global wax uses. Alternatives like soy wax and beeswax are generally better for the environment, but tend to be more expensive and producing them on an industrial scale needs to be done in a sustainable manner.