In short
The RUŌOD Lab formula editor holds each line as a material, a weight and a dilution, and its calculation engine derives everything else. Three dilution methods change a line in three different ways — keep its weight, keep its pure material, or keep both its pure material and the formula total by swapping free solvent — and the Dilutions & Scaling screen separates changing batch size from changing concentration. Predict each result first, then verify it: that is the habit this tutorial builds.
What you will learn
- Predict, before applying it, what Preserve Weight, Preserve Percentage and Exchange Solvent will do to a line and to the formula
- Configure the status bar to show the figures a study needs
- Use Production Targets and the two families of scaling, and say which figures each changes
- Verify every app result against the algebra of the mathematics course
Before this lesson: RUŌOD Lab Tutorial: Materials, Collections and Fields, Solvent in a Formula: What It Does to Your Numbers, A Formula as a Linear System
Before you start
You need the library tutorial, the three methods as arithmetic from solvent in a formula, and the algebra of the formula as a linear system.
The three dilution methods
Tap a line's dilution badge to open the dilution picker. It offers:
| Method | Line weight | Line's pure material | Formula total | Other lines |
|---|---|---|---|---|
| Preserve Weight | kept | changes | kept | untouched |
| Preserve Percentage | changes | kept | changes | untouched |
| Exchange Solvent | changes | kept | kept, if enough free solvent | free solvent drawn down |
Exchange Solvent uses only free solvent — a solvent line of its own — never the solvent carried inside another diluted material. The picker shows how much is available and the strongest dilution it allows; if there is not enough, the exchange is refused. Worked example: a line of 2 g at 10% (0.2 g pure) changed to 5% needs 4 g of weight. Preserve Weight leaves 2 g and 0.1 g pure. Preserve Percentage makes the line 4 g and the formula 2 g heavier. Exchange Solvent makes the line 4 g and takes 2 g from free solvent, so the total is unchanged.
The status bar
Beneath the entries, the status bar shows the figures you choose, configured in Tools → Formula Status Bar. Its metrics include entries, total weight, total solvent and its percentage, pure active and its percentage, available (free) solvent, total cost, and formula, absolute and relative percentages. For research, show pure active, absolute % and available solvent: they are the three figures dilution changes most often. A formula PDF prints the same metrics you selected.
Dilutions & Scaling
- Production Targets. Enter a batch weight and a concentration: the app calculates concentrate = batch × concentration, solvent = batch − concentrate, and the scaling factor from your current concentrate.
- Scale Formula (Batch Size). Scale Formula to Total Weight multiplies every line by target ÷ current total; Scale by Multiplier / Factor multiplies by the factor you give. Both preserve proportions, dilutions and dilution methods, so every percentage is unchanged.
- Scale Concentration (Fragrance Load). Scale Formula to Absolute % keeps pure material and adjusts free solvent so that pure ÷ total weight reaches the target; Scale Absolute % by Factor multiplies the current absolute percentage. A target above what zero free solvent allows is refused.
Check one by hand: 12.5 g pure in 15 g of non-solvent lines, target absolute 20%, requires 62.5 g total and therefore 47.5 g of free solvent — the app's own help text uses the same example.
What it will not do for you
- It does not choose a method; the choice says what you meant to keep constant.
- It does not know your balance: scaling down can produce weights below your practical minimum, which the uncertainty lesson shows matter.
- It does not nest formulas; a premix is entered as a material with its own dilution.
Practical exercise: Predict, apply, verify
- Enter a formula of at least eight lines, two diluted, with a free solvent line. Record every figure in the status bar.
- For one diluted line, write down what each of the three methods will do for a change of strength you choose. Apply each to a duplicate of the formula, and record the result.
- Apply Production Targets for a 50 g batch at a stated concentration, then Scale Formula to Absolute % for a different concentration. Predict each first.
- Verify every result with your Python script or by hand.
You have done this well if every prediction was written before applying, each method was applied to its own duplicate so the original stayed intact, every app figure matches your independent calculation to the fourth decimal or the difference is explained, and you can say which figures each operation changed.
Common mistakes
- Changing a dilution in the original. Duplicate first.
- Expecting Exchange Solvent to use carried solvent. Only free solvent counts.
- Using batch scaling to change concentration. Batch scaling preserves every percentage.
Key terms
- Free solvent
- Solvent present in a formula as its own line, as opposed to solvent carried inside a diluted material. Exchange Solvent can only draw on free solvent.
- Production target
- In the app, a batch size and concentration for a finished perfume, from which it works out the concentrate, the solvent and the scaling factor.
Knowledge check
Written and reviewed by the RUŌOD Lab team. This is general education, not legal, regulatory, medical or safety advice. Example dilutions and exercises are for learning, are not validated products, and have not been safety-assessed. Completing a lesson confers no qualification. How we check these lessons.