Soy wax starts life as soybean oil.
The oil found inside soybeans is naturally liquid at room temperature, so it cannot simply be extracted and poured into a candle. It first has to be processed and chemically altered to give it the more solid, wax-like properties needed for candle making.
The key step is called hydrogenation.
What is soy wax?
Soy wax is a vegetable-oil-based wax made primarily from hydrogenated soybean oil.
Soybeans contain oil made up largely of unsaturated fats. At normal room temperature, that oil remains liquid.
Hydrogenation changes the structure of some of those fats, increasing the proportion that remain solid at room temperature and giving the material the melting and solidifying behaviour required for candle wax.
Different manufacturers can produce different grades of soy wax depending on how the oil is processed and how the finished wax is formulated.
How is soy wax made?
The journey from soybean to candle wax involves several stages.
1. The soybeans are harvested
Soybeans are grown as an agricultural crop in many parts of the world.
After harvesting, the beans are transported to a processing facility where they are cleaned and prepared for oil extraction.
2. The beans are cleaned, cracked and flaked
The beans are cleaned to remove unwanted material before being cracked into smaller pieces.
The hulls can then be separated, and the soybean material is conditioned and rolled into thin flakes.
Creating thin flakes increases the surface area and makes extracting the oil more efficient.
3. The soybean oil is extracted
The oil is then separated from the soybean material.
Large-scale soybean processing commonly uses solvent extraction, often with hexane, although mechanical pressing is also used in some forms of vegetable-oil production.
This produces crude soybean oil as well as soybean meal, which has other uses, particularly in animal feed.
4. The oil is refined
Crude soybean oil contains substances that need to be removed before it is suitable for further processing.
Commercial refining can involve several stages, including:
- Degumming to remove phospholipids and other gums.
- Refining or neutralisation to remove free fatty acids and impurities.
- Bleaching using adsorbent materials to remove colour bodies and other trace compounds.
- Deodorisation using steam under vacuum to remove volatile compounds responsible for unwanted odours and flavours.
The result is a much more highly refined soybean oil.
The important step: hydrogenation
Refined soybean oil is still an oil rather than a candle wax.
To change that, the oil undergoes hydrogenation.
During hydrogenation, hydrogen is introduced to the oil in the presence of a catalyst, commonly nickel, under controlled temperature and pressure.
The process reduces some of the carbon-to-carbon double bonds found in the unsaturated fatty acids within the oil.
As the degree of saturation increases, the material becomes harder and its melting point rises.
In simple terms: liquid soybean oil is transformed into a material that can remain solid at room temperature but melt when heated by a candle flame.
Is all soy wax the same?
No.
There is no single universal soy wax formulation.
The degree of hydrogenation can be adjusted to change characteristics such as melting point and hardness. Manufacturers may also formulate waxes differently depending on whether they are intended for container candles, pillars, melts or other applications.
Research into vegetable-oil candle waxes has shown that partially and fully hydrogenated soybean oils can behave quite differently when melting and solidifying. That is one reason commercial candle waxes are carefully formulated rather than simply being untreated soybean oil made solid.
Is soy wax always 100% soy?
Not necessarily.
Some products are predominantly or entirely soy-based, while others are sold as soy wax blends.
Soy can be blended with other vegetable waxes, such as coconut or rapeseed wax, or with other ingredients to change characteristics such as hardness, adhesion, appearance and melting behaviour.
A blend is not automatically inferior. Candle making is largely about balancing wax, wick, fragrance and vessel so that the finished candle burns properly.
Is soy wax natural?
Soy wax is plant-derived, because its starting material is soybean oil.
However, describing it simply as “natural” can hide the amount of processing involved.
The beans are processed, the oil is extracted and refined, and the oil is then chemically altered through hydrogenation before it becomes candle wax.
That does not make soy wax undesirable. It simply gives a more accurate picture of how the material is produced.
Is soy wax renewable?
The raw material is renewable in the sense that soybeans are an agricultural crop that can be grown again.
This distinguishes soy from paraffin wax, whose raw material ultimately comes from petroleum.
But “renewable” and “environmentally harmless” are not the same thing.
Soy cultivation requires land, water, agricultural inputs, processing and transport. The environmental impact therefore depends partly on where the soy comes from and how it has been produced.
For a broader comparison, see our guide to soy wax and paraffin wax candles.
Does soy wax burn cleaner than paraffin?
You will often see this stated as an absolute fact, but the answer needs some qualification.
Controlled studies have found substantially less soot from hydrogenated soybean wax than paraffin under some test conditions.
However, candle emissions are also influenced by the wick, fragrance, wax formulation and the way the candle is burned.
No candle flame is completely soot-free, and simply choosing soy wax does not guarantee perfect combustion.
Keeping the wick properly trimmed and avoiding draughts can make a considerable difference. See our Candle Care Guide for more.
Does soy wax make candles last longer?
Soy wax is often associated with slower-burning candles.
Research comparing hydrogenated soybean wax with paraffin has found a slower consumption rate for soy wax under particular test conditions.
But the burn time of a finished candle also depends heavily on the wick, vessel diameter, fragrance, wax blend and candle design.
It is therefore better to judge the tested burn time of an individual candle rather than assume every soy candle will automatically last longer than every paraffin candle.
Why is soy wax used for candles?
Soy wax became popular because it provides candle makers with a useful plant-derived alternative to traditional petroleum-based waxes.
Depending on the formulation, it can offer:
- a relatively low melting point suited to container candles
- good compatibility with many candle fragrances
- a soft appearance and texture
- a renewable agricultural starting material
- the ability to be blended with other waxes for different performance characteristics
Like any wax, however, it has its own quirks. Soy wax can develop frosting, vary in appearance and behave differently as temperatures change.
From soybean to candle
The basic journey is straightforward:
Soybean → soybean oil → refined oil → hydrogenation → candle wax.
What looks like a simple block or flake of white wax has therefore been through several stages of agricultural and industrial processing before it ever reaches a candle maker.
Understanding that process gives a more useful picture of soy wax than simply describing it as “natural” or “eco-friendly”. It is a processed, plant-derived material with properties that make it particularly useful for modern candle making.
More candle guides: compare soy wax and paraffin wax, learn about soy wax frosting and mould, or read our Candle Care Guide.
