The two rules

What the other two leaves bring

Updated October 2026

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The perfume decant And the materials question travels with it So a decant is for a trip, not for storage The travel mouthwash, which is the good news Which is a genuine design advantage Sunscreen and lotion are the easy ones And a shampoo decant is a surfactant Being small changes the exceptions, not the class References

Two of the seven leaves arrive with rules of their own, and one of them is good news.

The perfume decant

High alcohol, so a Class 3 flammable liquid. Being 10 mL does not change its hazard class; it changes which exceptions are comfortably available. The written site on Fragrance has the shipping arithmetic.

And the materials question travels with it

Alcohol attacks plastics and adhesives, which is why the Fragrance shelf is entirely glass. A perfume decanted into a PET travel bottle is a slow failure waiting, and the bottle will often outlast a trip and not a season.

So a decant is for a trip, not for storage

Which is a reasonable thing to say in the product copy. A few days in a PET atomizer is a different proposition from six months, and saying so manages the expectation honestly.

The travel mouthwash, which is the good news

The mouthwash paragraph triggers on 3 g or more of ethanol per package, and that is a mass rather than a concentration. A small travel size can sit under it while the full-size bottle of the same product does not.

Which is a genuine design advantage

A travel format that falls outside a child-resistant packaging requirement is cheaper and easier to use. The Oral care property has the calculation, and it is worth running rather than assuming either way.

Sunscreen and lotion are the easy ones

Ordinary cosmetics with no threshold attached, where the only questions are the size limits and the closure. Most of this shelf exists for exactly those.

And a shampoo decant is a surfactant

Which foams in a reduced pressure environment far more readily than it does over a sink. Headspace and a closure that seals properly matter more for a foaming liquid than for a lotion.

Being small changes the exceptions, not the class

That is the distinction worth carrying away. A 10 ml perfume is still a flammable liquid and a travel mouthwash is still a mouthwash; what changes is which thresholds and limited-quantity provisions are comfortably within reach.

References

49 CFR 173.150, Exceptions for Class 3 (flammable and combustible liquids), the limited quantity provisions that reach a high-alcohol product such as a perfume decant, with inner packaging limits of 0.5 L, 1.0 L and 5.0 L by packing group and a 30 kg gross cap per package. law.cornell.edu

16 CFR 1700.14(a)(22), Mouthwash, which requires special packaging for mouthwash preparations containing 3 g or more of ethanol in a single package, with a narrow exemption for nonremovable pump dispensers meeting three further conditions. law.cornell.edu

49 CFR 175.10, Exceptions for passengers, crewmembers, and air operators. Paragraph (a)(1) excepts non-radioactive medicinal and toilet articles for personal use, including aerosols, in carry-on and checked baggage, requiring aerosol release devices to be protected against inadvertent release and limiting each person to 2 kg or 2 L in aggregate with no single container over 0.5 kg or 500 mL. law.cornell.edu

Written from federal regulation and from measured catalog data. The hazardous materials figures here are from 49 CFR 175.10 and are current as cited; the carry-on liquids limit is a TSA security requirement that changes without a rulemaking, so check TSA rather than any secondary source including this one. Airlines may also impose their own conditions.