How to store perfume materials

Store perfume materials cool, dark, full and sealed: in amber or opaque glass with tight caps, with as little air above the liquid as possible, in a cool cupboard or a fridge kept only for them. Air, light and heat are what age a material, and citrus oils and other terpene-rich materials go first. Label every bottle, dilutions included, with its name, strength, solvent and date.

What damages perfume materials?

Air. Oxygen slowly changes many materials, and it is the main reason an old bottle smells different from a new one. The catalog marks Orange Terpenes as oxidising easily and d-Limonene as prone to oxidation.
Light. Daylight on a clear bottle speeds the same reactions. Amber glass in a closed cupboard is the simple answer.
Heat. A warm shelf, a sunny windowsill or a room above a boiler ages everything faster and drives off the lightest part of a material every time the cap comes off.
Loose caps and shared pipettes. A loose cap loses top notes and lets air in; a pipette moved from one bottle to another contaminates both. One pipette per material.

Which materials age fastest?

Citrus oils and terpene-rich materials: Lemon Essential Oil, Sweet Orange Essential Oil, bergamot, orange terpenes, pine oils. Linalool and the oils rich in it, such as lavender, belong on the same list. IFRA treats this seriously: limonene and linalool carry no percentage cap in Category 4, but a specification on their peroxide value, a measure of how oxidised they are, and the IFRA advice with it is fresh stock and antioxidants. Pine-family oils such as turpentine are handled the same way. See limonene and linalool.

Heavy base materials, woods, resins and musks, generally keep better, but nothing keeps forever. For carriers, jojoba is described in the catalog as exceptionally resistant to oxidation, while kitchen oils go rancid.

Should I keep perfume materials in the fridge?

A fridge kept only for materials is a good home for citrus oils and fragile naturals, because cold slows oxidation. Three cautions:

Some things thicken, cloud or crystallise in the cold. Concretes and butters are solid anyway, jojoba can solidify, and a dilution of a crystal such as Vanillin can drop crystals at the bottom. A bottle with crystals in it is not the strength on its label until they have dissolved again.
Let a cold bottle reach room temperature before you open it. Otherwise moisture from the room condenses inside. Warm it gently in the hand, swirl until it is clear, then weigh.
Never share it with food, and keep your stock of alcohol out of it. Ethanol is flammable and keeps well in a cool cupboard.

Why do full bottles keep better?

Because the air above the liquid is what oxidises it, and a half-empty bottle has a lot of air. Buy in sizes you will use, and as a large bottle empties, decant it into smaller ones that are filled close to the top, keeping one working bottle and leaving the rest sealed. Use caps with a good liner, close them straight after weighing, and do not store bottles with a rubber dropper bulb in them.

Do antioxidants help?

They slow oxidation; they do not reverse it. The catalog lists BHT, which its note describes as added at 0.05 to 0.1 percent to protect citrus terpenes and aldehydes, Vitamin E (alpha-tocopherol), used for carrier oils and oxidation-sensitive naturals, and Rosemary Antioxidant - Extract. Whatever you add to a stock bottle, write it on the label, and when it ends up in a formula, count it there as a material.

How should I label dilutions?

A dilution needs more on its label than the stock bottle it came from, because it looks identical to the neat material and behaves ten times weaker. Write:

The material, named exactly as the stock bottle is.
The strength: "10 percent", by weight.
The solvent: alcohol, Dipropylene glycol or another.
The date it was made, and which stock bottle it came from.

An unlabelled 10 percent bottle weighed as if it were neat puts a tenth of the intended material into a formula, and nothing on the scale warns you. The dilution arithmetic shows how far that error travels. Keep dilutions closed as carefully as the stock: a dilution in alcohol that loses solvent through a loose cap gets stronger than its label.

What records should I keep?

For every bottle: the supplier, the lot if it is given, the date it arrived, how much is left, and the shelf life the supplier states, if it states one. The catalog carries no general shelf life, and a supplier's figure for its own material is the best guide there is. Add a short smelling note when a bottle is new. A year later, that note is how you tell whether the material has changed or your memory has.

In PerfuMate each bottle on your shelf carries its strength, solvent, supplier and purchase date; give a material a shelf life and a dated bottle is marked once it passes it, a dilution made from stock becomes its own bottle, and a low-stock warning tells you before a bottle runs out mid-formula. How long a finished perfume lasts. Start a formula, free.