Two failure modes, both preventable: it leaks, or it melts.
Against leaking
- Tape the cap or the pump, so it cannot turn in transit
- Each item in its own sealed bag
- Those bags in a second sealed bag, so one leak does not reach everything else
- Absorbent paper around the lot
- Bubble, then a box close to the size
Never post a liquid loose in a padded envelope. One leak in a mailer ruins the parcel and everything in it.
Against heat
Many products soften, separate or melt. Anything wax, cream or balm is at risk in a parcel left in the sun or in a hot vehicle.
You cannot control the van, so: avoid posting into the worst of the heat where you can, say in the listing that a product is heat-sensitive, and tell the buyer in the parcel note to let it settle before opening.
Glass
Bubble generously and box — never a soft mailer. Glass bottles are the most commonly broken thing in this category, and a broken bottle of liquid is also a leak.
Check what your courier carries
Some products are restricted — aerosols and anything flammable in particular. Ask before you promise a delivery price, because the difference comes off your own balance. How delivery is charged.
Questions people ask
Can I post an aerosol?
Ask your courier first. Many will not carry them, and some services refuse them outright.
Should I remove the outer carton?
No. The carton holds the batch code and the dates, which is part of what the buyer is buying.
What if something leaks anyway?
Photograph every parcel before it goes. That photograph is what settles it. How returns work.