Cold process soap runs in nine steps: weigh the oils, weigh the lye and water, make the lye solution, combine at temperature, blend to trace, add fragrance, pour into molds, cut after a day or two, and cure for weeks before labeling. The lye step is the dangerous one: sodium hydroxide is caustic, so whoever mixes it wears gloves and goggles, adds lye to water and not the other way round, and weighs it exactly to the recipe's lye calculation. Curing lets the soap finish saponifying and dry out, so it's mild and lasts. A bar that is true soap, sold only as soap, is outside FDA's cosmetic rules; add a skin claim and it becomes a cosmetic. In the example below, a North Carolina soap maker runs a batch.
The short version
- Nine steps: weigh oils, weigh lye and water, lye solution, combine, trace, fragrance, mold, cut, cure.
- Weigh lye exactly to the recipe's lye calculation.
- Gloves and goggles; add lye to water, never water to lye.
- Blend to trace, then add fragrance.
- Cure for weeks before selling.
- True soap sold only as soap is outside FDA's cosmetic rules.
- TaroStack records each batch with its oil and fragrance lots. More below.
The nine steps
| Step | What happens | What to record |
|---|---|---|
| 1. Weigh oils | Olive, coconut and other oils weighed | Oil lots, weights |
| 2. Weigh lye and water | Sodium hydroxide and distilled water weighed | Lye lot, weights |
| 3. Lye solution | Lye added to water, with gloves and goggles | Temperature |
| 4. Combine | Lye solution into the oils at temperature | Temperatures |
| 5. Trace | Stick-blended to trace | Time |
| 6. Fragrance | Fragrance or essential oil stirred in | Fragrance lot, weight |
| 7. Mold | Poured into loaf molds, covered | Molds |
| 8. Cut | Unmolded and cut into bars | Bars, weights |
| 9. Cure | On racks with air around each bar | Start and end dates |
Making it by the hundred bars is in how to make soap in bulk, and wrapping in how to package soap bars for sale.
The rule behind step 9's label
FDA treats an article as soap, outside its cosmetic rules, only if most of it is alkali salts of fatty acids, its cleaning comes from those, and it's labeled, sold and represented only as soap; a cleansing bar that isn't true soap, or one claiming to moisturize or deodorize, is a cosmetic (21 CFR 701.20). How a soap business is set up is in soap business plan.
An example: a 400-bar batch
Cedar Hollow Soap Co., the made-up soap maker in Asheville, North Carolina, I use in these examples, pours cold process soap in loaf molds for shops and markets:
| Step | What happened |
|---|---|
| Weigh | Olive oil lot OO-0901, coconut lot CO-0828, shea lot SH-0815; lye lot NA-0820 to the recipe's calculation |
| Lye solution and combine | Gloves and goggles; lye into water; combined at 100°F |
| Trace and fragrance | Light trace; lavender essential oil lot LV-0905 |
| Mold and cut | 10 loaf molds; cut after 36 hours into 400 bars of 4.5 oz |
| Cure | On racks from Sep 12 to Oct 17, five weeks |
| Label | Lot CH-0910, "Lavender Soap" with its weight and ingredients |
The label says "soap" and nothing about the skin, which keeps the bars true soap; the shop's request to add "moisturizing" would make them a cosmetic. Weighing the lye to the calculation for every batch, and writing it down, is the one step that can't be eyeballed.
Get the run sheet
Download the soap production run sheet. Two sheets: a blank run sheet to print for each batch, with the nine steps, the check at each and its target, and spaces for the actual reading, the time and initials; and the same run filled in from the example. It's an ordinary Excel file with no macros, and it works in Google Sheets, LibreOffice and Numbers.
Where this stops working
The run sheet covers one batch. Five oils, a lye lot, an essential oil lot, and 400 bars curing for five weeks: when a customer reacts to one bar, the trace has to run to the fragrance lot and every bar made with it.
How TaroStack does it
TaroStack records each batch with its oil, lye and fragrance lots, so a bar's lot leads back to its ingredients.
Batches by lot. Each batch takes the oils, lye and fragrance off stock with their lots.
Bars by lot. Each batch gets its lot, and records good and rejected bars.
Where it went. Each shop's order records the lot it got, so one report shows every shop that got a fragrance lot.
| The job | Clipboard | In TaroStack |
|---|---|---|
| Which fragrance went into a batch | A note on the mold | Batches by lot |
| Bars cut and rejected | Counted at the end | On the batch |
| Which shops got a lot | Invoices | One recall report |
Recipes, batches, lots and recalls are on every plan, from $49 a month. The first 30 days are free, with no credit card. If you'd like a hand setting up, ask, and we'll do it with you.