With proper storage, essential oils retain their effectiveness over years, maintaining their wide range of applications.
The best material for storage of essential oil are glass, stainless steel or aluminium containers. However there are reasons and applications for using alternative materials.
Before deciding which container to use for storage of essential oils we need to make a firm distinction if we want to store them in their pure form or in a dilution?
Pure essential oils wield considerable potency and should always be safeguarded in airtight glass, Stainless steel or aluminium containers.The potent nature of these oils makes plastic containers susceptible to deterioration over time, resulting in damaging leaks, contamination of the oil and even potential oil loss.
Diluted essential oils, blended with carriers like coconut oil and sweet almond oil, water and solvents dilute the strength of pure essential oils. These diluted mixtures can be stored in plastic containers, however not all plastics are created equal. Here is a list of candidates, that fit the parameters:
HDPE
This is also known as High Density Polyethylene, stands out due to its robust and dense composition. With stronger bonds and longer chains than regular plastic, HDPE is a suitable choice for diluted essential oils.
HDPE falls under the category of Plastic #2 and is usually labeled accordingly by manufacturers.
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PET Plastic
PET plastic, or Polyethylene Terephthalate, is another option for storing diluted essential oils. However, PET plastic is typically designed for single-use applications, which means it might not be as sturdy as HDPE.
Containers made from PET plastic usually have a number one (#1) label on their bottom.
LDPE and PP Plastics
While HDPE and PET plastics are top choices, LDPE (Low-Density Polyethylene) and PP (Polypropylene) plastics can also be suitable, depending on your storage needs. Both LDPE and PP plastics are commonly found around the house and can work well with essential oils.
LDPE is waterproof and chemically resistant, while PP is known for its toughness and chemical resistance. LDPE is less dense than HDPE, making it more lightweight and convenient for travel. PP is often found in shampoo caps, opaque containers, and even certain toys.
MDPE
Medium-Density Polyethylene belongs to the thermoplastic category and is part of the polyester family. Similar to HDPE, MDPE is a linear polymer derived from ethylene through a catalytic process. Nevertheless, MDPE possesses lower density and sensitivity, and it boasts superior resistance to stress cracking compared to HDPE. MDPE is manufactured without branching, resulting in a densely packed structure with high density and exceptional chemical resistance. It exhibits remarkable resilience against both, diluted and concentrated acids, alcohols, and bases. Additionally, MDPE displays good resistance to aldehydes, esters, aliphatic and aromatic hydrocarbons, ketones, as well as mineral and vegetable oils. It finds great utility in food-related products, and it holds FDA, NSF, and USDA approvals for direct contact.
MDPE is not known for releasing chemicals suspected of causing cancer or hormone disruption. However, similar to many plastic products, repeated reuse over time can lead to the gradual breakdown of chemicals.
Recycling MDPE is widespread, with the recycling symbol "2" representing it.
PS
Polystyrene is an amorphous and glassy polymer known for its high versatility, facilitated by its excellent flow properties that allow it to be molded into various shapes. It tends to be rigid and fragile, with a relatively low melting point. It is cost-effective and finds suitability in food-related products, boasting FDA, NSF, and USDA approvals for direct contact.
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PS is not associated with the leaching of chemicals suspected of causing cancer or hormonal disruptions. However, similar to many plastic products, multiple reuse instances can result in the gradual degradation of chemicals.
Recycling of PS is not commonly practiced, and it exhibits slow biodegradation. Its recycling symbol is marked as "6."
PF
Phenolics are synthetic layered sheets produced through heat, pressure, and various materials like paper, cotton, glass, linen, or canvas. The layering process, known as polymerisation, results in a laminate that remains firm and cannot be softened. This quality facilitates drilling, sanding, and machining. PF is frequently characterized by hardness, brittleness, and cost-effectiveness. It offers resistance to heat, acids, deformation, shock, stress, and electricity. PF often serves as an insulator in electrical components.
PF is not commonly recycled and demonstrates sluggish biodegradation.
PMMA
Acrylic, also referred to as Poly(methyl methacrylate) (PMMA), is a transparent thermoplastic frequently used as a substitute for glass due to its remarkable versatility. PMMA is lightweight, strong, and durable, showcasing exceptional clarity. It resists weather, chemicals, and UV light. Products incorporating PMMA often incorporate additives, fillers, or other modifications to achieve specific properties.
PMMA is not commonly recycled and does not biodegrade.
Its recycling symbol is indicated as "7."
PCTG
Within the terephthalate polyester category, a lesser-known yet glycol-modified copolyester, PCTG, emerges. It is especially used in the 3D printing Industry. PCTG shares similarities with PETG in application and molecular structure, yet it boasts elevated chemical resistance, a broader range of print temperatures, and enhanced durability. These qualities not only render PCTG more versatile for printing but also retain the safety and recyclability characteristics of PETG.
In terms of aesthetics, PCTG can yield either a matte or glossy finish depending on the chosen print temperature. The distinguishing factor in PCTG lies in its remarkable Izod Impact Resistance, allowing it to endure significantly higher impacts compared to similar filaments, all while maintaining similar tensile strength and heat resistance.
SILICONE
Although not categorised as a plastic, silicone serves as a lightweight and readily available alternative for storing essential oils. Similar to glass, silicone does not exhibit reactions with essential oils.
Silicone actually outperforms plastic due to its inherent resistance to degradation. Unlike plastic, both glass and silicone are designed for long-lasting use without requiring frequent replacement.
The notable advantage of silicone lies in its lightweight nature and wide availability, similar to plastic.
Given the flexibility of many silicone containers, there's a possibility that the cap could come undone, potentially leading to oil spillage, evaporation or increased oxidation.
There have been some anecdotal reports of essential oils causing deterioration in silicone. We advise to still ensure oil dilution when using them.
Resin Identification Codes
Plastics feature a resin identification code that aids in identifying the specific plastic type. It is the number enclosed by a recycling symbol. Currently, there are seven designated plastic types under this system, established in 1988 to encourage recycling.
The numbering system also reflects the overall simplicity (and hence, cost-effectiveness) of recycling, with 1 indicating the easiest and 6 and 7 representing more challenging categories.
When a number is absent, the arrows forming a triangular shape resemble the universally recognised recycling symbol, a generic representation of recyclability. Later updates to the RIC have replaced the arrows with a solid triangle, aiming to clarify consumer misunderstandings about the significance of the RIC and the fact that the presence of a RIC symbol on an item does not guarantee its recyclability.
Oil Dilutions for different Plastics
The dilution ratio is a crucial factor with essential oils. The diluted state of essential oils generally entails concentrations that won't significantly interact with containers. Nevertheless, it's prudent to prioritise glass, particularly if storing homemade cleaners or personal care items for an extended period. Similarly, the incorporation of essential oils into beverages results in highly diluted solutions.
PET, PETG, MDPE, PCTG, HDPE, PMME and Silicone materials are suitable for accommodating higher concentrations of essential oils. Even some of those, like silicone might be able to withstand much higher concentrations, we recommend not to exceed a ratio of more than 5% essential oil to be sure.
LDPE, PS, PF and PP Plastics can als be used but we recommend only using essential oil ratios, below 2% for those.
Plastic that should not be used
It is advisable to refrain from using essential oils in conjunction with the following types of plastic:
Water bottles
Solo cups and their equivalents
Plastic drinking straws
Plastic kitchenware
Thin plastic containers
Styrofoam
Essential Oils Unsuitable for Plastic
Certain essential oils, such as:
citrus oils
lemon
grapefruit
tea tree oil
They should never be stored in plastic, even when mixed with a carrier oil. These oils can interact with the plastic, causing damage or degradation.
Lids, Dispensers and droppers
HDPE plastic for components such as lids, orifices, and diffusers are the best option,, ensuring they won't degrade when in contact with essential oils. Generally, HDPE plastic and plastics numbered 1 (PETE) and 2 are considered safe.
When selecting essential oils, consider that bottles featuring a screw-top cap with a rubber dropper integrated into it, may pose a potential weak point. The presence of rubber droppers with some of the available materials for bulbs is thus inadvisable. Sometimes the oil bottles will be jostled around, such as in a purse or bag, or they will be at times lying flat for a considerable amount of time, in which case the liquid can get to the rubber bulb. Especially concentrated oil can cause the rubber bulb to deteriorate and potentially spoil the essential oil.
Some of the conventional bulb types are made from thermoplastic elastomers or from natural rubber. Both are predominantly employed for alcohol-based products and products with low acidity levels that won't harm the rubber bulb. They are not advisable for the use with essential oils.
Rubber bulbs that are safe to use with essential oils:
Nitrile: a specialised bulb designed for oil-based and highly acidic liquids
Silicone: does not interact with essential oils
Rubber Bulbs that should not be used with essential oils:
Monprene
Santoprene
Neoprene®
Natural Rubber
At PlantaExquis we exclusively use Silicone and Nitrile rubber bulbs for our pipettes.
An alternative to rubber dropper tops are orifice reducers. This transparent insert within the bottle's opening serves as an integrated dropper and is made from HDPE. This component is also referred to as a euro dropper. Unlike the material used in rubber dropper bulbs, orifice reducers are constructed from materials that withstand exposure to essential oils.
Not all oils store equally well
While essential oils have a shelf life, oxidation can result in the loss of therapeutic properties and, occasionally, the oil's aroma. Interestingly, some oils, like sandalwood, mature over time, becoming more robust in scent.
Citrus oils are more prone to oxidation, necessitating airtight storage in a dark place with consistent temperature.
Certain oils, such as Fennel and Aniseed, can solidify during storage due to natural waxes. Gentle warming by holding the bottle in your hand or allowing it to sit in warmer conditions can restore these oils to liquid form.
During warmer seasons, safeguard carrier oils intended for dilution by storing them in the refrigerator.
Other factors when storing essential oil
Proper storage extends beyond the choice of containers—it involves keeping oils in a dark, cool environment, away from direct sunlight. The sun's UV rays can raise oil temperatures, leading to diminished oil quality. To counter this, it's highly recommended to store pure essential oils in coloured glass containers. Hues like cobalt blue and amber-tinted glass deflect sunlight, safeguarding oils during storage.
Irrespective of the chosen bottle type, ensure to seal oils securely with a high-quality, airtight lid before storage. Failure to tightly replace the cap can lead to oil evaporation, resulting in substantial financial losses. While investing in suitable essential oil packaging may incur initial costs, it prolongs the oils' longevity.
Given their flammability, it is also crucial to store essential oil bottles away from open flames and fire sources. When properly packaged, storing essential oils poses no greater risk than storing flammable products such as alcohol. Centralising your essential oil storage simplifies periodic checks on their condition.
Finally, ensure that essential oils are out of reach of young children, as their concentrated form can be hazardous.
Opting for Glass
Factors like heat, light, oxygen, and moisture can impact the shelf life of essential oils. When possible, it's advisable to store essential oils in glass bottles.
For optimal results, consider using amber glass bottles to store essential oils. Amber glass protects oils from sunlight, high temperatures, and deterioration. Amber or cobalt glass bottles are highly recommended for essential oil storage, ensuring their longevity and potency.
In the end, choosing the right plastic or glass container ensures the safekeeping of your essential oils, allowing you to enjoy their benefits for years to come.
Bulk Transport
We find the best solution for housing our essential oils for bulk transport are sizeable aluminum bottles.. This packaging not only guarantees secure transportation and storage of the oils but also facilitates effortless dispensing and management when dealing with larger quantities. Whether you're utilising these oils in aromatherapy, cosmetics, soap and candle crafting, or even rebranding under your own label, this solution emerged as the optimal selection.
Guiding Your Customers
When marketing essential oil products to customers, provide them with storage recommendations specific to the products they purchase. Include a storage tip sheet for both pure essential oils and their diluted counterparts, ensuring customer satisfaction. Proper storage practices prevent early expiration and any potential dissatisfaction.
Instructions for Customers
For skin application, it's crucial to dilute pure essential oils with a carrier oil. In case of direct skin contact, wash the area with a carrier oil rather than soap and water. This prevents the essential oil from penetrating the skin. Soap and water can be used to remove the carrier oil.
Dispense oils into a clean spoon (preferably stainless steel) before adding them to a mixture or recipe, as even a slight excess of pure essential oil can alter the outcome.
Essential oils, even in diluted form, should never be applied near sensitive areas like the ears, eyes, or mucous membranes, as they can cause severe irritation and complications.
Exercise caution with children; some oils, especially in concentrated form, can cause harm. Consult a doctor or essential oils expert before using oils on children, especially those diagnosed with epilepsy.