Short answer
Perfumers dilute powerful or solid materials — commonly to 10%, 1% or 0.1% — so that small amounts can be weighed accurately and smelled meaningfully. Make a dilution by weight: for 10 g of a 10% solution, weigh 1.00 g of the material and add solvent to a total of 10.00 g. Choose a solvent that suits the material and the end product (perfumer's alcohol, dipropylene glycol and isopropyl myristate are common), label it as its own stock item, and always record the dilution next to the weight when the solution goes into a formula.
Why dilute raw materials at all
- Weighing precision. A formula may need 0.02 g of a material. On a 0.01 g balance that is two divisions, and the error could be half the amount. As a 1% solution, the same 0.02 g of material is 2.00 g of liquid, which the same balance weighs to within half a percent.
- Evaluation. Many materials smell completely different neat and in dilution. Some, at full strength, are simply overwhelming; smelling them at 1% or 10% is closer to how they behave in a perfume.
- Handling. Solids such as vanillin, coumarin or musk ketones are easier to dose as solutions. Very viscous materials become pourable.
- Economy. Expensive materials go further when you are not over-dosing trials by accident.
How to make a dilution
Dilutions are made by weight, with percentages meaning grams of material per 100 g of solution (w/w).
- Choose the batch size and strength. For 10 g at 10%: 1.00 g material, 9.00 g solvent.
- Tare a clean, labeled glass bottle on the balance.
- Weigh in the material first. Record the actual weight.
- Add solvent until the total reaches the target. If the material weight came out at 1.02 g, the target total for a 10% solution becomes 10.20 g.
- Close and mix until fully dissolved. Solids may need time, gentle warmth or both.
- Label it: material name, strength, solvent, date, and your initials or batch code.
Weighing the material first and adjusting the total is more accurate than trying to hit an exact material weight with a viscous liquid or a powder.
Serial dilutions
To make a 1% solution from a 10% one, take 1.00 g of the 10% solution and add solvent to 10.00 g. Making 0.1% from 1% is the same step again. Serial dilution keeps weighed amounts large, but each step adds a little error and the solvent of the parent solution is carried along, so name the solvent consistently.
Choosing a solvent
| Solvent | Good for | Watch out for |
|---|---|---|
| Perfumer's alcohol (ethanol) | Dilutions destined for alcohol-based perfume; smelling on blotters | Evaporates when the bottle is opened, slowly raising the dilution's strength; flammable |
| Dipropylene glycol (DPG) | Stable, nearly odorless stock dilutions; dissolving many solids | Barely evaporates, so it stays in the finished product; does not suit every material or every end use |
| Isopropyl myristate (IPM) | Oil-based products and materials that dissolve poorly in glycols | Oily; may not be compatible with alcohol-based finished products at higher levels |
| Triethyl citrate (TEC) | An alternative low-odor solvent used by some perfumers | Check compatibility with your materials and end product |
Two cautions. First, some "solvents" are fragrance materials in their own right: benzyl benzoate, for example, is used as a diluent for some materials but also appears on the EU's list of fragrance allergens that must be labeled above set thresholds. Count it as a material, not as invisible solvent. Second, the solvent you choose ends up in the finished product, in proportion to how much dilution you use. A formula with many DPG dilutions makes an alcohol perfume that contains DPG.
Accounting for dilutions in a formula
A dilution in a formula is recorded as the solution, with its strength: "Ambroxan 10% in DPG — 1.00 g". From that, its pure active is 0.10 g and it carries 0.90 g of DPG. The formula's total weight includes the DPG; the material's share of the scent does not. That distinction is why a diluted row has three different percentages, explained in formula %, absolute % and relative %.
If you later switch to a different dilution of the same material, decide first what should stay constant — the weight on the balance, or the amount of material. Keeping the amount of material constant at a weaker dilution means weighing more solution, which changes every other row's share of the formula. The perfume dilution and calculations guide covers the arithmetic.
Keeping dilutions under control
- Treat each dilution as a stock item with its own label, date and quantity, linked to the material it was made from.
- Use the same strengths throughout the lab (for example 10%, 1% and 0.1%) so formulas and labels are predictable.
- Record the material lot used for each dilution; if the material changes, the dilution changes too.
- Close alcohol dilutions promptly, and remake them rather than topping them up.
- Check dilutions for haze, color change or crystals before use, and discard what has changed.
Stock counts for dilutions belong in the same inventory as the neat materials — see fragrance raw material inventory. Accurate weighing of the small amounts involved is covered in how to weigh perfume ingredients accurately.
In RUŌOD Lab, a material record can list the dilutions you keep of it, each formula row carries the dilution it was weighed at, and a material can be flagged as a solvent so that it contributes weight but no pure active to the calculations.
The equation behind every dilution — and how to blend two strengths or rescue a weak one — is in the perfume dilution formula. Crystalline materials have their own problems, covered in dissolving solid aroma chemicals.
Frequently asked questions
Is a 10% dilution 1 ml in 10 ml?
Not in perfumery. Dilutions are by weight: 1 g of material in 10 g of solution. Volume-based dilutions vary with each material's density and are hard to reproduce.
How long does a dilution keep?
It depends on the material and the solvent. A dilution generally ages like the material itself, and some degrade faster in solution. Date every dilution and check it before use; see fragrance raw material shelf life.
Should I smell materials neat or diluted?
Mostly diluted. Smelling at 10% or 1% on a blotter is safer for your nose and much more informative about how the material will behave in a formula.
Written and reviewed by the RUŌOD Lab team. This article is general education about perfume formulation and record-keeping; it is not legal, regulatory or safety advice, and the examples are illustrations, not validated commercial formulas. How we write and check these guides.