Fragrance oil
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What it is
A blended aroma material sold for use in soap, candles and bath products. It is bought by the ounce, used by the gram, and chosen on performance rather than on price.
The archetype
A craft supply liquid, 30 to 500 mL, narrow neck, poured. The note describes exactly this: fragrance oil and additives bought to decant from rather than to sell on.
Two sets of technical facts
For soap: behaviour at high pH, acceleration, discolouration, usage rate. For candles: flash point, maximum load in the wax, cold and hot throw. The same bottle, two documentation jobs.
Flash point is not optional information
It governs how the product may be shipped and it tells a candle maker when to add it to the wax. Publishing it is both a safety courtesy and a competitive advantage.
It attacks plastics and adhesives
Concentrated fragrance is hard on containers, liners and labels. Glass is the conservative answer and the shelf carries 44 glass Boston rounds and 100 glass containers in total.
Amber, for the same reason as everywhere
Fragrance materials oxidise and light accelerates it. For a product a customer will keep for a year between uses, that matters more than it does for a finished consumer item.
Decanting is the business
Buying in volume and selling in 30 to 120 mL is the model, which makes the fill, the label and the lot mark the production process rather than a formulation.
Which puts all the quality risk in handling
Cross-contamination between scents, a bottle filled from the wrong drum, a mislabelled lot. None of those is a chemistry problem and all of them end a customer relationship.
Sell it in glass if you can afford to
It solves the compatibility question, it protects the contents, and it signals that the supplier understands the material. For a product bought on trust by people comparing suppliers, that signal is worth real money.
And label the scent so it survives the oil
Fragrance runs down the outside of a bottle every time it is poured. A label and adhesive chosen for a dry product lifts within months, and an unlabelled bottle of fragrance oil is an unusable bottle of fragrance oil.