Understanding Dilutions in Perfumery

Why perfumers dilute materials

Dilution is more than a convenience. It allows us to evaluate potent materials at manageable strengths, weigh small quantities more reliably, and compare ingredients under consistent conditions. Some solids and viscous resins are also easier to handle when dissolved in a compatible solvent.

A dilution is a preparation with a defined concentration. A 10% solution is not the same thing as adding “ten drops” of material to a vial: drops vary with the liquid, dropper, and temperature. In a working laboratory, mass is the more reproducible starting point.

Use weight, not volume, for reproducible formulas

For a weight-by-weight dilution, the calculation is straightforward: concentration (%) = 100 × mass of aromatic material ÷ total mass of solution. The total mass includes both the material and its solvent.

To make 10.00 g of a 10% w/w solution, weigh 1.00 g of material and add 9.00 g of solvent. For 10.00 g at 5%, use 0.50 g of material and 9.50 g of solvent. For 10.00 g at 1%, use 0.10 g of material and 9.90 g of solvent. These are mass percentages, not volume percentages.

A quick dilution worksheet

Target batch: 10.00 g total solution. At 1%: 0.10 g material + 9.90 g solvent. At 5%: 0.50 g material + 9.50 g solvent. At 10%: 1.00 g material + 9.00 g solvent.

For another batch size, multiply the desired total mass by the target concentration expressed as a decimal. Example: a 25.00 g batch at 5% needs 25.00 × 0.05 = 1.25 g of material, plus 23.75 g of solvent. Always confirm the sum equals your intended total.

Choosing a solvent

SDA-40B perfumer’s alcohol is commonly used for alcoholic fragrance evaluations where the material is soluble and the application permits it. Dipropylene glycol (DPG), triethyl citrate (TEC), and other carriers can be useful in different systems, but they may change how a material dissolves, evaporates, and smells.

Not every aromatic material dissolves in every solvent or at every concentration. Check supplier guidance, verify clarity and stability, and label the solvent alongside the percentage. If a dilution becomes cloudy or forms crystals, do not assume the concentration is accurate throughout the container. Avoid heating flammable solvents to force dissolution.

Stock solutions and serial dilution

A stock solution can simplify repeated work. Suppose you have a verified 10% solution and want 10.00 g at 1% using the same solvent. You need 1.00 g of the 10% stock—which contains 0.10 g of aromatic material—and 9.00 g of additional solvent.

Remember that the stock itself already contains solvent. When using a stock in a fragrance formula, its full weighed mass enters the batch, but only part of that mass is active aromatic material. Record both the stock concentration and the quantity added, especially when comparing formulas with different dilutions.

Label and document everything

Each container should identify the material, concentration with its basis (for example, 10% w/w), solvent, preparation date, and batch or source where relevant. Use clean containers and a scale with sufficient readability for the intended weights. Tare carefully, and avoid claiming more precision than your balance can provide.

A 0.01 g balance may be suitable for many small preparations, but weighing 0.01 g of a potent material can create a large relative error. Prepare an intermediate dilution when needed rather than attempting to measure below your equipment’s practical capability. Follow the material’s SDS, ventilation requirements, and applicable handling precautions.

Accurate dilutions make experiments easier to repeat, compare, and improve. The habit of documenting them is as valuable as the calculation itself.