In the shift towards green chemistry and an eco-friendly lifestyle, essential oils have moved from spas to household cleaning cupboards. While often valued for their pleasant aroma, many essential oils possess powerful chemical properties that make them functional active ingredients in detergents, sprays, and laundry products. However, creating formulas with these volatile compounds requires more than just adding oil to water.
More than just a scent: functional properties
Antimicrobial action
Terpenes, phenols, and aldehydes disrupt the cell membranes of bacteria and fungi. Tea tree oil is a broad-spectrum antiseptic. Thyme contains thymol — a powerful antimicrobial agent for plant-based disinfectants.
Solvent properties
Citrus oils contain d-limonene — a powerful solvent that removes grease, adhesive residue, and wax. Ideal for degreasers and kitchen cleaners.
Pest repellent
Peppermint and eucalyptus are natural repellents for insects and spiders. An added benefit for floor cleaners and sprays.
Which oils for which tasks
Oil | Key component | Application | Task |
|---|---|---|---|
🍋 Lemon / Orange | d-Limonene | Degreasers, dishwashing liquids | Grease removal |
🌿 Tea tree | Terpinen-4-ol | Bathroom cleaners, mould sprays | Antimicrobial |
💜 Lavender | Linalool | Laundry gels, fabric softeners | Fragrance + relaxation |
🌱 Peppermint | Menthol | Glass cleaner, floor washing | Freshness without streaks |
🌲 Eucalyptus | 1,8-Cineole | Bed linen laundry, deodorisers | Combating dust mites |
🌲 Pine | Alpha-pinene | Heavy-duty floor cleaners, disinfecting scrubs | Deep cleaning |
The fundamental problem: oil + water = ?
If you just add essential oils to a water-based cleaner, the oil will float to the surface. The first spray will be pure water, and the last will be pure essential oil, which could damage surfaces or cause skin irritation.
How to stabilise the formula
Surfactants
In dishwashing liquids and laundry gels, the main detergent components usually keep enough oil in suspension.
Solubilisers
For watery products (sprays, glass cleaners): Polysorbate 20 or PEG-40. Ratio: from 1:1 to 5:1 (solubiliser : EO). Mix together before adding water.
Alcohol
Ethanol or isopropyl alcohol helps disperse oils but is less stable than surfactants. Suitable for quick-use products with a short shelf life.
Essential oils are NOT preservatives! Even if they have some antimicrobial properties, they are too weak and volatile. Once they evaporate, that tiny bit of protection goes with them. In water-based formulas, a broad-spectrum preservative is mandatory. More details in our article on preservation.
Safety: 3 important points
Surface damage
Undiluted citrus oils (d-limonene) can corrode certain types of plastic (polystyrene). Store concentrates in glass or PET / HDPE plastic.
Skin irritation
Essential oils are potential allergens. In products that come into contact with the skin (hand soap, dish soap), the concentration should be: < 1–2%.
Pet safety
Critically important! Some oils are toxic to pets. Details in the callout below.
Cats: their livers cannot process phenols/monoterpenes. Tea tree, peppermint, citrus, and pine oils can be toxic if inhaled heavily or absorbed through their paws.
Dogs: more tolerant, but tea tree oil can be toxic in high doses.
If you have pets, keep this in mind when choosing cleaning oils! More on pet safety in article on pet cosmetics.
Bonus recipe: kitchen spray
Antimicrobial degreasing spray (100 g)
Phase | Ingredient | % |
|---|---|---|
A | Distilled water | 94.5 |
A | Euxyl K712 (preservative) | 1.5 |
B | Polysorbate 20 (solubiliser) | 3.0 |
B | Tea tree EO (antimicrobial) | 0.5 |
B | Lemon EO (degreasing) | 0.5 |
C | pH adjuster (citric acid 50% / NaOH 10%) | q.s. |
Target pH: 4.5–5.0 | 100.0 |
Combine phase A (water + preservative), stir until dissolved
In a separate vessel, combine phase B: first the Polysorbate 20, then add the essential oils drop by drop, stirring thoroughly until fully solubilised
Add phase B to phase A drop by drop, stirring thoroughly
Check and adjust the pH to 4.5–5.0 (phase C). More on pH adjustment in our pH guide
Pour into a spray bottle (glass or PET/HDPE). Label
Essential oils in cleaning products are a powerful way to move away from synthetic fragrances and boost cleaning power using plant chemistry. By understanding solubility requirements and safety profiles, you can create effective, fragrant products that clean the home without polluting the air. The main thing to remember is: stabilisation, preservation, and pet safety.
Read also: Preservation in cosmetics • Pet shampoo
Oksana Walker
Cosmetic chemist, founder of the Walker Formulation Academy
IFSCC • SCS • IAA • IAC
