Resins are among the most forgiving aromatic materials to keep. They have no water to spoil, they do not evaporate quickly, and they have preserved themselves on tree bark for months before anyone bought them. But they are not inert, and the mistakes people make are the same ones every time: heat, light, air and the wrong container.
The four rules
Cool. Benzoin softens at roughly body temperature and flows at not much above. Labdanum is sticky at room temperature. Elemi and galbanum are soft oleoresins that go runny in warmth. A cool cupboard, not a sunny shelf or a spot above the radiator. The fridge is unnecessary for solid resins and causes condensation.
Dark. Light oxidizes aromatic molecules. Vanillin, benzaldehyde and the cinnamates in benzoin all degrade faster in daylight. Amber or opaque containers, or a closed cupboard.
Dry. Gum resins such as frankincense and myrrh are partly water-soluble and absorb humidity, going tacky and eventually mouldy on the surface. A sealed jar in a dry room; a silica gel packet if you live somewhere humid.
Sealed. Air brings oxygen, which oxidizes, and carries scent away. Sealed also means the resins do not scent each other: benzoin in particular will make everything in the same drawer smell of benzoin.
Containers
- Glass with a tight lid is best. Amber glass or a dark cupboard.
- Tins work for whole tears if lined or if the resin will not soften; sticky resins bond to metal.
- Plastic bags and tubs are the worst choice for the long term. Resins absorb and release plasticizers, sticky resins fuse to plastic, and thin bags are not airtight. Fine for a week, not for a year.
- Paper is fine for very dry gum resins in a dry climate, and otherwise no.
Label with material, origin and date. Resins look alike after two years in a cupboard.
Whole versus powder
Whole tears have a small surface area and keep for years. Powder has an enormous surface area and loses its volatile top within months, especially benzoin, whose vanillin and benzaldehyde go first. Buy tears and grind what you need, when you need it. A cheap coffee grinder reserved for resins works; chill sticky resins first.
Extracts: resinoids, absolutes, tinctures
Resinoids and absolutes are concentrated, oxidize faster than raw resin, and are expensive. Keep them in small, full, tightly closed amber bottles. Decant into smaller bottles as you use them so there is less air in the headspace. In hot climates refrigerate. Tinctures are mostly alcohol and evaporate through any imperfect seal; keep them tightly capped and away from flame.
Signs of trouble
- Sour or vinegary smell: fermentation of gum resins that got damp, or oxidation of old tincture.
- Dull, flat smell: oxidized powder or old absolute.
- White bloom on the surface: usually crystallized acids (benzoic acid on benzoin, sometimes on storax), harmless. Mould is fuzzy and smells musty; discard.
- A solid fused lump: heat. Break up and move.
How long things last
| Material | Well stored |
|---|---|
| Benzoin tears | 5+ years |
| Benzoin powder | under 1 year |
| Frankincense, myrrh tears | 5+ years |
| Labdanum (raw) | years, but softens |
| Elemi, galbanum (oleoresins) | 1–2 years before hardening and dulling |
| Resinoids, absolutes | 2–3 years, longer refrigerated |
| Home tincture | years if sealed |
And one more
Keep them away from other scented things. Resins are fixatives by nature; they absorb odours as readily as they give them off. A benzoin jar that lived next to camphor will smell of camphor for a long time.
Frequently asked questions
Does benzoin resin go bad?
Not in the sense of spoiling, but it loses aroma, oxidizes, and can soften and clump in heat. Kept cool, dark and sealed, tears keep well for five years or more. Powder loses scent within a year.
Should I keep resins in the fridge?
Not necessary and not ideal: condensation when the jar comes out is worse than mild room temperature. A cool cupboard away from heat and sunlight is right. The exception is absolutes and resinoids in summer heat, which can go in the fridge in a tightly closed bottle.
Why did my resin tears stick together?
Heat. Benzoin softens around body temperature and above; in a warm room the tears slowly fuse into a mass. It is still usable. Break it apart and move it somewhere cooler.
Sources & further reading
- benzoin
- storage
- resins
- care
