Building a lab formula sheet: gram weights and batch sizing

A lab formula sheet is the document that separates a perfume idea from a perfume product. It is the artefact you mix from at the bench, the one you hand to a contract filler, and the one a regulator asks for if they want to verify your safety dossier. This post is about what should be on it and why.

What a lab sheet contains

A complete lab sheet has six sections. Smaller studios often combine sections two and three onto one page, and that is fine, the principle is that every entry on the sheet is reconstructable from the records:

1. Header, formula name, version, author, date, batch ID.
2. Composition, every material in the concentrate, with percent of the concentrate, role (top / mid / base), and supplier.
3. Mixing instructions, gram weights for the target batch size, ordered by addition (typically base → mid → top, then alcohol last).
4. Lot and supplier traceability, for each material, the lot number used in this batch and the date received.
5. QC checks, pH, density, colour, clarity at 4 °C, smell on a blotter at 24 h and 7 d.
6. Sign-off, initials and date for each step.

Sections one through three are the formula. Sections four through six are the batch, the specific physical event of mixing this concentrate on this date. A good sheet keeps them on the same page so they are never separated.

Sizing a batch

Every formula starts as a concept at 100 %, a list of percentages that add to one hundred, and is mixed at a target batch size in grams. The sizing decision is mostly economic:

Stage	Concentrate	Notes
Trial / submission	5–20 g	Single sample, internal smell.
Refinement	20–50 g	Multiple variants A/B at the bench.
Pilot batch	100–250 g	First batch you fill into bottles.
Production batch	500–2000 g+	Inventory for several months of orders.

Trace materials become difficult to weigh accurately at small batch sizes. A material at 0.05 % in a 10 g concentrate is 5 mg, a balance that reads to 1 mg starts to lose precision at that level. The standard solution is to keep 10 % working dilutions of any material below ~0.5 %, and to weigh the dilution rather than the neat material.

The grams math, in two equations

The first equation gives you the gram weight for each material, given a target concentrate batch size. The second tells you how much concentrate to dose into a finished bottle batch, useful when you mix one large concentrate batch and dose it across multiple bottle sizes.

Worked example

A 200 g concentrate batch of an EDP. The formula sheet lists jasmine absolute at 4.5 %, iso E super at 12 %, and Hedione at 18 %. The mixing column reads:

Material	Percent	Grams
Jasmine absolute	4.50 %	9.000 g
Iso E super	12.00 %	24.000 g
Hedione	18.00 %	36.000 g
… (remaining materials)	…	…
Total	100.00 %	200.000 g

Round to three decimals on the sheet. Round more aggressively at the balance only if the material is over ~5 % of the batch.

Mixing order

The bench convention for fine fragrance is bottom-up:

1. Base notes first, labdanum, sandalwood, musks, vanillin, fixatives. These are usually the densest and most viscous; mixing first lets them dissolve into the lighter materials added on top.
2. Heart notes second, florals, spices, hedione.
3. Top notes last, citrus, aldehydes, lighter aromachemicals. Top notes are most volatile; minimising their time at room temperature reduces evaporative loss before the bottle is sealed.
4. Alcohol last of all, added at the end of the concentrate maturation, just before bottling.

Some perfumers prefer to add highly diffusive aromachemicals (iso E super, Ambroxan) early so the rest of the formula "settles into them." Both approaches produce identical concentrate; the order matters only for bench ergonomics and observability.

Lot traceability

The single most important non-formula entry on a lab sheet is the lot number for each material used. Two batches of the same material from the same supplier can drift by a few percent on key constituents, natural batches drift more, synthetics less. If a finished batch smells off and you don't know which lot of bergamot went into it, you cannot diagnose the problem.

A practical lot record contains:

• Material name (and INCI / CAS for unambiguity).
• Supplier and PO or invoice number.
• Lot number as printed on the supplier's container.
• Date received and date opened.
• Storage condition (fridge / dark cabinet / inert atmosphere).

The lot number flows from the receipt log to the lab sheet to the finished batch record. This is the chain a regulator or a contract filler will trace if there is ever a quality issue.

QC checks worth running

Most indie perfumers skip QC, then learn the hard way that a few cheap checks catch most batch errors before the bottles are filled:

• Density. Compare against the previous batch on a 5 mL volumetric flask. A drift of more than ~1 % suggests the alcohol or a major component was misweighed.
• 4 °C clarity. Chill a sample for 24 h. Cloudy or precipitating? You may need to cold-filter or revisit the dosing of resinous materials.
• Blotter smell at 24 h and 7 d. The 24 h check catches gross errors; the 7 d check confirms the dry-down matches your reference batch.
• Top-note check at 5 min. Within five minutes of dilution, the top notes should match your reference. A flat or burnt top is the most common symptom of a top-note miscount.

What a lab sheet earns you

The discipline of writing a complete lab sheet is what turns a perfumer into a producer. It is also what makes you legible to fillers, contract labs, and regulators when you need them. A formula in your head is an artwork; a formula on a versioned lab sheet, with batch records and lot numbers, is a product.

If you are starting out, the move is not to design the perfect template on day one, it is to write something down for every batch from now on, and let the template improve as you find the gaps. The next batch of your best formula should match the previous one. The lab sheet is how.