Essential Oils: The Complete Buying and Formulation Guide
Essential oils are formulated more by instinct than by system for most beginners — a drop of this, a drop of that, until it smells right. That works for a home candle, but not for a product intended for sale, where usage rate, safety data and consistent sourcing all matter. This guide covers what you actually need to know.
What is an essential oil?
An essential oil is a concentrated aromatic compound extracted from a single plant source — typically by steam distillation or cold expression — capturing that plant’s characteristic scent and, in many cases, functional properties beyond fragrance alone. This is what distinguishes essential oils from fragrance oils, which are manufactured blends rather than single-source natural extracts.
Essential oils are potent, concentrated ingredients — most cosmetic formulations use them well under 1% of total batch weight, and some oils (tea tree and peppermint among them) carry specific maximum usage guidelines that vary by finished product category and intended use. Always check current safety data for the specific oil and application before finalising a formula, particularly for leave-on skin products, which generally carry stricter limits than rinse-off products.
Blending basics
Essential oils are commonly blended for a more complex aroma than a single oil provides — citrus notes (Orange, Lemon) pair well with floral or herbaceous notes (Lavender), while Peppermint and Eucalyptus combine naturally in invigorating, cooling-themed blends. Start with small test blends at low overall concentration before scaling into a full batch.
Essential oil vs fragrance oil: when to use which
If a single natural extract delivers the exact scent and functional profile you want, an essential oil is usually the better choice — it’s a recognisable, single-ingredient story for your label. If you need a specific, complex scent that doesn’t exist as a natural single-source extract — a strawberry or vanilla-cocoa profile, for example — that’s fragrance oil territory. See our Guide to Cosmetic Fragrance Oils for the full comparison.
Storage and shelf life
Essential oils are best stored in dark glass (which is how we supply them), away from heat and direct light, to slow the oxidation that gradually degrades both scent and functional properties. Citrus oils in particular tend to have a shorter stable shelf life than floral or herbaceous oils and are worth using within their supplier-recommended window.
Frequently asked questions
Can I apply essential oils directly to skin?
Undiluted essential oils are not intended for direct skin application in most cases — they should be diluted into a carrier oil or finished formulation at an appropriate usage rate. See our Carrier Oils guide for oils commonly used to dilute essential oils.
How many drops of essential oil should I use per 100ml?
This depends entirely on the specific oil and product type — there’s no single safe answer across all essential oils. Always calculate by weight percentage against current safety guidance for that specific oil, rather than estimating by drop count.
Do essential oils expire?
Yes — they oxidise and lose potency over time, faster with heat, light and air exposure. Dark glass storage (like the bottles we supply in) and a reasonably prompt use-by window help preserve both scent and functional properties.
Shop our essential oils
Browse the full range in our Essential Oils category, available from small test-batch sizes up to bulk packs.
