What goes wrong

The container failed

On this page9

Panelling Environmental stress cracking The cap swelled The bottle went soft, or sticky Loss of contents with no visible leak The common root Test the way the product will live Keep a retained sample of every batch References

These failures are slow, which is why they are discovered by the customer and not by you.

Panelling

The bottle draws inward as a solvent evaporates through the wall or as the headspace cools. It looks like damage in transit and it is not. It is a permeability problem and it points at the resin.

Environmental stress cracking

Fine cracks at the shoulder or around the neck, in a bottle that is otherwise intact. It is the classic polyethylene failure mode with certain contents, and it appears weeks or months in rather than on day one.

The cap swelled

Or the liner did. The contents attacked the one part nobody tested, and the first sign is a cap that will not seat or a seal that has gone soft.

The bottle went soft, or sticky

Usually heat plus solvent together. Check what the product saw in transit; PET stops at 120F and a closed van in summer is well past that.

Loss of contents with no visible leak

Permeation through the wall. The weight drops, the product thickens, and the package looks perfect. Weigh a few units at intervals during testing and this is caught in weeks rather than in reviews.

The common root

A material chosen on the chemical resistance column alone, where seven of the ten materials carry the same rating. The separation is in the temperature range and in testing your own formula.

Test the way the product will live

Filled, closed, on its side, warm, for as long as you can stand. Weigh them, open them, look at the liner. Everything on this page is visible in that test and invisible in any shorter one.

Keep a retained sample of every batch

In the production container. When a customer reports a failure eight months later, a retained sample is the only way to tell a packaging problem from a formula problem.

References

The Davis Pack Supply resin chart, derived from C&P’s own published ratings across 2,150 SKUs and held as <code>material_property</code>: chemical resistance and a service temperature range per material. Glass rates High at 5 of 5 and runs -100 to 300F; PP, HDPE, PET, LDPE, PVC, phenolic and urea rate Good at 4 of 5; PS rates Semi at 2 of 5. The temperature ranges differ sharply even within the same rating, PET topping out at 120F against HDPE’s 190F and PP’s 240F.

The Davis Pack Supply catalog, measured 17 October 2026. The adhesive and finish shelf is 664 rows: 234 containers and 430 closures, derived from two packaging archetypes across six leaves, with cr_required set on every one of them.

Written from 16 CFR 1500.14(b)(8), 1500.121 and 1700.14, and from the catalog as it stood on 17 October 2026. Whether a particular product is an art material, what its chronic hazard labeling should say, and whether its closure must be child resistant are determinations about a specific formula; the first of those is a question for a toxicologist by regulation, and nothing here substitutes for one.