Batch records, lot codes and good manufacturing practice

A notebook of what you made is a start. The difference between a notebook and a batch record is whether it can answer three questions, weeks or years later, without guesswork: what went into this bar, how it was made, and where the rest of the batch went. This guide covers what to write down, how to number batches, how to follow a supplier’s lot through to your customers, and what the rules on good manufacturing practice ask of a small workshop.

Why keep records

A recall. A supplier writes to say a lot of coconut oil was contaminated, or a customer reports a reaction. The questions are the same either way: which batches used that lot, and who bought bars from them. FDA’s draft guidance on cosmetic good manufacturing practice puts it plainly: records should be “adequate to conduct an effective recall”, and “initial distribution records identifying the consignee, the product, and the lot or control number should be retained”.

A complaint. The batch code on the bar leads to the record: which fragrance lot went in, what the lye solution weighed, what the free-alkali check showed, whether anything went wrong on the day. Without it, you cannot say what was in the bar a customer is asking about. Where the soap is a cosmetic, some reactions must be reported to the authorities, as the section on complaints below explains.

The law’s paperwork. In the EU and Great Britain every soap has a product information file, and it must contain “a description of the method of manufacturing and a statement on compliance with good manufacturing practice” (Article 11 of Regulation 1223/2009). The batch records are the evidence behind that statement.

And your own soapmaking. The fragrance that seized two batches in a row, the new supplier’s lard that traced faster: patterns like these only show up across records. The troubleshooting guide starts from the same questions.

What the rules ask, market by market

The texts are listed under Sources. A US soap becomes a cosmetic with a cosmetic claim on its label; the labelling guide explains where that line falls.

In the US, “small business” under MoCRA means average gross annual sales of cosmetics in the US under 1 million dollars over the previous three years, adjusted for inflation, unless the business makes certain products such as those used around the eye. Until FDA’s own rules arrive, its 2013 draft guidance sets out what FDA expects, and it is where most of the specific wording in this guide comes from. It is a draft of non-binding recommendations, and for a true soap it is good practice rather than FDA’s ask.

What a batch record holds

FDA’s draft guidance lists what a batch production record should include: “all ingredients (name, code, lot number, quantity, etc.) added to the batch”, “all production steps”, “in-process sampling, controlling, and adjusting steps”, the “batch and finished product lot or control numbers”, and “the finished products control status - accepted or rejected”. For a batch of cold-process soap, that comes to five sections.

The sections of the site’s printable batch record, which follow the headings of FDA’s draft guidance.

The planned-and-weighed pair of columns is the part that protects your customers. A lye mistake starts at the scale, and the record makes you look twice.

The soap pH guide covers the free-alkali check, and why we leave the zap test out; the curing guide covers why bars are released only after a cure.

Lot codes

The batch code, or lot number, is the short reference printed on every bar’s label that leads back to its record. The EU requires “the batch number of manufacture or the reference for identifying the cosmetic product” on the label (Article 19(1)(e)), and FDA’s draft guidance asks that finished product packages “bear permanent meaningful, unique lot or control numbers and you have a coding system that corresponds to these numbers”.

Makers already number batches in their own ways, and any scheme works if it keeps three rules.

1. Unique. Two batches must never share a code, including two made on the same day.
2. Never reused. A deleted batch’s code may still be on bars in a shop, and handing it to a new batch would make two different soaps answer to one number. The batch log always gives the next code after the highest ever used, and never fills a gap.
3. On everything. The label, the rack while the bars cure, the record, and the sales record for any shop order.

The batch log numbers batches from a pattern you choose. Tokens stand for the parts that change, and the sequence counts within whatever the rest of the code says: with the date in the code, the letter starts again at A each day; with only the year, the number starts again each January.

Codes worked by the batch log’s own numbering for batches made on 23 September 2026. {JJJ} is the day of the year, 001 to 366.

Supplier lots and traceability

Every drum of oil, sack of lye and bottle of fragrance your suppliers send carries their own lot or batch number, on the container or on its certificate of analysis. Write it down when the delivery arrives, and write it on the container if the supplier’s label will not survive your storeroom. FDA’s draft guidance asks for raw materials to be “held in closed containers and stored off the floor” and “labeled with the identity, lot number, and control status (release or quarantine)”.

Traceability is then one step back and one step forward. From a bar in a customer’s hand, back through its batch code to the record and the supplier lots it used. From a supplier’s lot, forward to every batch that used it and every shop or customer who bought from those batches. The second direction is the harder one, because sales at a market are anonymous. They do not need to be named, but shops, wholesale buyers and posted orders can be, and those are the sales a recall has to reach.

When a batch is logged and you have not said which container it came from, the site’s stock ledger assumes the oldest delivery still on the shelf went in first, which is how stock is normally rotated; name the lot and that comes first instead. Keep each lot’s paperwork with it: the supplier’s specification or certificate of analysis, the safety data sheet, and for a fragrance the IFRA certificate and the allergen declaration, whose figures can change from lot to lot of an essential oil.

Good manufacturing practice in a small workshop

ISO 22716 gives guidelines “for the production, control, storage and shipment of cosmetic products”, covering their quality rather than staff safety or the environment. Its clauses run from personnel, premises and equipment, through raw materials, production and finished products, to deviations, complaints and recalls, change control, internal audit and documentation. A kitchen-table maker who reads it will find parts, such as the quality control laboratory and subcontracting, that do not apply to them. The ideas scale down well, and FDA’s draft guidance covers the same ground in plainer words.

• The space. Clean and orderly, with surfaces that can be wiped down, and soapmaking kept apart from food: the equipment guide covers keeping soapmaking tools apart from kitchen ones. FDA asks for “floors, walls, and ceilings constructed of smooth, easily cleanable surfaces”.
• The scale. Equipment should be “of suitable size and accuracy for measuring, mixing, and weighing operations” and “calibrated regularly or checked according to an SOP with results documented”. For a maker that means checking the scale against a known weight, such as a calibration weight, at a regular interval you set yourself, and writing the reading down.
• The raw materials. Closed, labelled, off the floor, with the lot number on each, and the oldest used first.
• The making. A written recipe followed as written; every container labelled, above all the lye solution; the record filled in as you go.
• The finished bars. Curing bars are in quarantine until you release them. Keep one sample bar from each batch until it is past its best-before date: FDA’s draft guidance asks for samples of approved lots of finished products to be “retained for an adequate time period”.
• Changes. A changed recipe is a new version, and a batch keeps the recipe it was made from. In the batch log, editing a recipe afterwards never rewrites the batches already made with it.

Complaints, reactions and recalls

Record every complaint with the batch code, what happened and what you did, however slight it seems. For a complaint of a reaction, FDA’s draft guidance lists what to capture: the kind and severity of the injury, the body part, the product and code numbers, whether medical treatment was sought, and how it resolved.

Some reactions must also be reported. In the EU and Great Britain the responsible person and distributors notify serious undesirable effects to the national authority “without delay” (Article 23). In the US a cosmetic’s responsible person reports a serious adverse event to FDA within 15 business days, and keeps records of every adverse event report for six years, or three for a small business. A true soap is outside FDA’s rules, but the same record serves you anyway.

A recall runs on the records described above: find the lot, list the batches that used it, list the shops and customers who had those batches, contact them, and keep what comes back apart from saleable stock until you have decided what to do with it. FDA’s guidance asks that recalled products be “identified and stored separately in a secure area”.

How long to keep records

The texts set two periods. In the EU and Great Britain the product information file is kept for ten years after the last batch of the product is placed on the market. In the US, records of adverse event reports on a cosmetic are kept six years, or three for a small business. For batch records themselves, keep each one at least until every bar from the batch is past its best-before date, and in the EU and Great Britain for as long as the product information file whose statement on good manufacturing practice they support.

The batch log, lot tracing and the printable record

The site’s tools are built around the same record.

• Log this batch, on the lye calculator, records a batch with a snapshot of the recipe as made, and gives it the next code in your scheme.
• The batch log keeps each batch’s temperatures, trace, gel, outcome and cure date. The free plan keeps up to 10 batches; the Maker plan keeps every batch, with cure weigh-ins, photos, rack labels and QR codes.
• On the Maker plan, stock joins in: before a batch is logged you see what it will take from your shelves, its boxes and labels with its ingredients, and logging it takes them. On the Business plan each delivery keeps its supplier lot, and a lot search lists every delivery of a lot and every batch it went into. Name the customer on a shop order in finished goods, and the same search tells you whom to call.
• Also on the Business plan, the printable batch record carries the planned weights from the engine, the INCI names, and each ingredient’s supplier lot beside it, with columns left empty for what you weighed and ticked. A QR code beside the batch code opens the batch in the log, and the footer says what the page is: a record to fill in and keep, not a certificate.

The pricing page lists what each plan includes. The records they produce feed the labelling and, in the EU and Great Britain, the product information file described in the safety assessment guide.