Beginner perfumer · 61
Twelve replies about tape and boxes, and nobody mentioned what is inside the bottle
· 17 min read
Somebody on r/DIYfragrance was about to post their first homemade perfumes and asked how to package them. All 12 replies covered how to wind teflon tape, whether electrical tape looks tacky, and how to do box-in-a-box. Every one of them is physical protection. Not one mentions that what is in the bottle is a flammable liquid. Ethanol's flash point is 9.44 C, so an alcoholic perfume is under that line before you add anything. The aroma materials are not all safe either: of the 13,166 library records whose flash point parses in Celsius, 9.9 percent sit below 23 C and 13.0 percent between 23 and 60, which is close to a quarter between them. And the GHS hazard field cannot help, because only 369 of 42,225 records have one.
About a 6 minute read.
Ten hours ago:
"So I got these really thin 10ml tall glass decant bottles along with paraflim, electrical tape, and teflon tape. Also purchases crinkle paper packaging and padded bubble mailers. Everything the internet said I got it. However I'm still not feeling confident to mail a first order.
So far my process is wrap threads in teflon clockwise, tighten cap, and electrical tape around where the cap and glass meet to seal. But someone irl said the electrical tape looked tacky so I got paraflim and I'm not sure the results are much better.
Then for packaging do I simply put the glass vials in a plastic ziplock of sorts along with crinkle paper and then put that in the bubble mailer. Would that be enough?"
Twelve replies: means-test it by knocking the box about, pack it tightly, wrap the atomiser and the seal, box in a box, where to buy small boxes.
Not one of them mentions what is inside the bottle.
Ethanol's flash point is 9.44 C
Flash point is the temperature at which a liquid gives off enough vapour to be ignited.
The database gives ethanol 49.00 F TCC, which is 9.44 C.
That is below room temperature in most places. So an alcoholic perfume is a flammable liquid before a single aroma material goes into it.
The asker's problem is not how many turns of tape. He asked "would that be enough", and beyond the physical-protection layer there is a layer he does not know exists.
What about the mixture
A perfume is not neat ethanol. It is ethanol, water and a set of aroma materials, most of which have high flash points. Does that pull the bottle's flash point up?
Liaw and Chiu presented a mathematical model for predicting the flash point of miscible mixtures in the Journal of Hazardous Materials in 2007. They validated it on ternary aqueous-organic systems, water plus methanol plus ethanol or isopropanol, and concluded that the model predicts the flash points of these solutions from the flash points of the individual components. Where ternary interaction parameters are unavailable, a model built on binary interaction parameters gives acceptable predictions too.
The phrase that matters is "from the flash points of the individual components". In an ethanol-dominated mixture, the flash point is governed by the ethanol. Adding a few percent of high-flash-point aroma materials does not move it from 9 C to above 60.
(I have not calculated the flash point of any particular perfume. That needs mole fractions and activity coefficients, and I did not do it. This is a direction, not a number.)
And the aroma materials are not all safe
The layer below is what surprised me.
14,316 records carry a flash point (34% of the library's 42,225), and 13,166 of those parse to a Celsius value. The distribution:
| Flash point band | Records | Share | With 10+ suppliers |
|---|---|---|---|
| < 23 C | 1,304 | 9.9% | 210 |
| 23 – 60 C | 1,707 | 13.0% | 371 |
| 60 – 93 C | 2,980 | 22.6% | 542 |
| > 93 C | 7,175 | 54.5% | 716 |
Close to a quarter (22.9%) sit below 60 C. Of those, 581 have ten or more suppliers, which is to say you can buy them.
The ones below 23 C with ten or more suppliers, from the bottom:
| Material | Flash point | Suppliers |
|---|---|---|
| acetaldehyde | -40.00 C | 94 |
| dimethyl sulfide | -36.67 C | 81 |
| isopropyl mercaptan | -33.89 C | 16 |
| propionaldehyde | -26.67 C | 27 |
| hexane | -23.30 C | 18 |
| acetal | -20.56 C | 44 |
| propyl mercaptan | -20.00 C | 24 |
| ethyl formate | -19.44 C | 49 |
| isobutyraldehyde | -18.89 C | 39 |
| acetone | -17.22 C | 33 |
The one at the top, acetaldehyde, has 94 suppliers, putting it among the best-supplied materials in the library. And its boiling point is 20 to 21 C.
It boils at room temperature.
Do not rely on the GHS field
I assumed I could filter on the GHS hazard statements field. Checking it, I cannot.
Of 42,225 records, only 369 carry any GHS hazard statement at all, or 0.9%.
Where the field exists it is trustworthy: 64 records have both a GHS statement and a flash point under 60 C, and 57 of them (89%) carry an H224, H225 or H226 flammability statement.
The problem is not accuracy. It is that the field barely exists.
The flash point field covers 34%, close to forty times more.
One pair makes the point:
| Flash point | Suppliers | GHS field | |
|---|---|---|---|
| acetaldehyde | -40.00 C | 94 | H224 Extremely flammable liquid and vapour |
| dimethyl sulfide | -36.67 C | 81 | empty |
Two materials, flash points less than 4 degrees apart, one labelled and one not.
If you decide what to be careful with by looking for a flammability warning, you will miss the second one.
This article is not giving you regulatory advice
Postal and courier rules for flammable liquids differ by country and change over time. I am not the source for that, and I have not read any carrier's terms.
What I can give is the database side:
- Ethanol's flash point is 9.44 C
- Roughly a quarter of the materials on your shelf have flash points below 60 C
- What those numbers are called on a carrier's form, and what you have to declare, is a question for the carrier
The asker says he has no orders yet and just wants to send some to family. That is exactly when to find out.
What you can actually do
- Check flash points before you check tape. Every material's flash point field is on its data page.
- Do not filter on the GHS field. It covers 0.9% of records. Use the flash point field, at 34%.
- Pay particular attention to the 210 materials below 23 C with ten or more suppliers. Acetaldehyde and dimethyl sulfide have 94 and 81 suppliers respectively, so they are easy to end up with.
- Acetaldehyde also needs refrigeration. Its storage field reads "refrigerate in tightly sealed containers", and it boils at 20 to 21 C. That is a storage problem as well as a shipping one.
- On physical protection the forum is good, so follow it. Box in a box, wrap the atomiser and the seal, ziplock. Those 12 replies are correct; they are just incomplete.
- Ask the carrier, not the forum. The right source for this question is the terms, not somebody's experience.
What this doesn't establish
- I have read no carrier or postal regulations. Every number above is a physical property, not a regulatory determination.
- I did not calculate the flash point of any perfume. Liaw 2007 says a model can compute it from components; that needs mole fractions and interaction parameters, which I did not do.
- The 23 C and 60 C lines I read back out of the database's own GHS wording (H225 for "highly flammable", H226 for "flammable"). I did not check the thresholds against the GHS source documents.
- 13,166 is what parsed to Celsius. The flash point field has 14,316 records; the rest use formats my parser could not read and are not in the statistics.
- 34% coverage means two thirds of materials have no flash point data. There may be lower ones among them.
- Some flash points are marked (est). I mixed estimates with measurements in these counts.
- The 57/64 = 89% has a denominator of only 64, being every record with both a GHS statement and a parseable flash point under 60 C.
- Supplier count is not the same as availability. It is the number of suppliers this library recorded.
- Acetaldehyde "boiling at room temperature" refers to the neat material at 760 mmHg. What people usually buy is a 10% or weaker solution, which behaves differently.