Lotion is mostly water, and water is where bacteria and mold grow, so a lotion's shelf life starts with a preservative that's been shown to work in that formula. That's what a challenge test does: a lab adds microbes and checks that the preservative kills them. After that, shelf life is about stability: the lotion separating, thinning, changing color or smell. A pump bottle keeps fingers out; a jar doesn't. In the example below, a Kailua skincare maker's sealed pump bottles passed every test through day 365, and they're dated 273 days from the batch, a 25% margin. Below is what ends lotion's shelf life, how the container changes it, the study, the date on the bottle, and a free template.
The short version
- Lotion has water in it, so it needs a preservative.
- A challenge test shows the preservative works in your formula.
- Separation, thinning, color and smell end a stable lotion.
- Pumps keep fingers out; jars let them in.
- Run a real-time stability study, with a lab count at each pull.
- Print a batch code and a date; a period-after-opening symbol too.
- TaroStack gives every batch its date from the shelf life you set. More below.
What ends its shelf life
| What ends it | What happens | What slows it |
|---|---|---|
| Microbes | Bacteria, yeast and mold grow in the water | A broad-spectrum preservative, proven by a challenge test; clean equipment |
| Separation | Oil and water split | The right emulsifier at the right percentage; mixing to the recipe |
| Smell and color | Oils oxidize; fragrance shifts | Antioxidants; opaque bottles; cool storage |
| Contamination in use | Fingers in a jar carry microbes in | Pumps or tubes; "Use within 6 months of opening" |
The year around the lotion is in lotion business plan, and what goes on the bottle in cosmetic labeling requirements.
How it's stored
| Stored | In the example's tests | On the label |
|---|---|---|
| Sealed pump bottle, room temperature | Passed every test through day 365 | Dated 9 months from the batch |
| Open jar, in use | Not part of the study | Pumps only, for that reason |
| Hot storeroom | Thinned and separated by month 4 in a side study | "Store below 85°F" |
The challenge test came first: there's no point dating a lotion whose preservative hasn't been shown to work.
An example: a shelf life study
Hoʻola Botanicals, the made-up skincare maker in Kailua, Oʻahu, I use in these examples, had its lotion challenge-tested by a lab, then kept sealed 8-ounce pump bottles from one batch on a shelf and sent one to the lab at each pull:
| Test | Pass if | Day 0 | Day 30 | Day 90 | Day 180 | Day 365 | Day 540 |
|---|---|---|---|---|---|---|---|
| Total microbial count, lab, CFU/g | at most 100 | 10 | 10 | 10 | 10 | 10 | 20 |
| Separation, 1 to 5 | at most 2 | 1 | 1 | 1 | 1 | 2 | 3 |
| Odor change, 1 to 5 | at most 2 | 1 | 1 | 1 | 2 | 2 | 3 |
| pH | at most 6 | 5.2 | 5.2 | 5.3 | 5.4 | 5.5 | 5.8 |
| All pass? | Pass | Pass | Pass | Pass | Pass | Fail |
Everything passed through day 365; at day 540 the lotion had started to separate and its smell had changed. Taking a 25% margin off day 365 gives 273 days, about nine months. How the pulls and margin are planned is in shelf life testing.
The date on the label
No federal rule requires an expiration date on a cosmetic; the maker is responsible for the product staying safe for as long as it's sold and used, and a stability study is how a small maker knows. Many print a batch code, an expiration or best-by date, and the open-jar symbol with a number of months, the period after opening. What MoCRA asks of a small maker is in mocra small business, and handing the making to someone else in cosmetic co-packer.
Get the template
Download the lotion shelf life study template. One sheet: the product, the lot tested, the day it was made, how it's stored and the margin to leave; then each test with its limit and the result at each pull. It marks each pull pass or fail, finds the last day everything passed, takes the margin off, and gives the shelf life for the label and the date for a batch made today. It's an ordinary Excel file with no macros, and it works in Google Sheets, LibreOffice and Numbers.
Where this stops working
The study gives one date for one lotion. Three scents, batches every month, bottles at a spa and two shops, and a new fragrance that has to go back through testing: someone has to date each batch and send the oldest bottles first.
How TaroStack does it
TaroStack gives every batch its date from the shelf life you set, and sends the oldest out first.
Dates from the shelf life. Each lotion carries its shelf life in days, and each batch's lot gets its production date and the date that follows from it.
First-expired-first-out. Orders take the oldest lots first by default, and a spa can be set to take only stock with enough days left.
What's coming up. A forecast shows what will expire unsold and what it costs, and anything thrown out is recorded with its reason, expired or spoiled, so waste shows by item.
| The job | Spreadsheet | In TaroStack |
|---|---|---|
| The date on a batch | Worked out by hand | From the shelf life, on the lot |
| Which batch goes out first | Dates on tape | First-expired-first-out |
| Stock with enough days for a spa | Checked by hand | The customer's shelf-life rule |
| What expired last month | Not counted | Waste by reason |
Lots, dates, first-expired-first-out and the expiry forecast 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.