Glass or plastic

Hot fill decides most of it

The product goes into the jar hot by design. That rules out materials that deform at fill temperature, and it rules them out at the moment of filling rather than gradually. A container chosen for a cold-filled product and used for a hot-filled one fails in a way that is obvious and expensive.

Acid over a long shelf life

This is an acidified product sitting on a shelf for a year. Glass does not care. It is also the reason the no-metal rule exists elsewhere in the process, and the same logic applies to anything the product sits against for months rather than minutes.

What glass costs you

Weight and breakage, and both are real. A case of filled jars is heavy enough that freight is a line item rather than an afterthought, which is what catches makers on their first mail order. Breakage costs twice: the jar, and what it does to everything packed near it.

Where plastic genuinely answers

Food service and large formats, where the container is opened in a kitchen rather than displayed and where dropping it on a tile floor is a routine event. That is a different product line rather than a cheaper version of the retail one, and it usually wants a different fill process as well.

Decide which line a size belongs to before choosing its container, because a gallon for a restaurant and a 16 oz for a shelf are answering different questions.

There is also a reuse expectation attached to glass in this category that is worth knowing: a sauce jar often gets kept, which is free brand presence on a shelf in somebody’s kitchen for years. It is a small thing and it is one of the few places where the more expensive container keeps paying after the sale.

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