The code

Permanently visible to the naked eye

On this page13

The requirement Two qualifiers, both doing work Which rules out several ordinary approaches On glass the options are narrow None of which is a property of the jar The alternative in the text is the product And the code carries three facts In code, not in words Which is why it can fit on a jar at all And the period has to change often enough So the code is a traceability tool The lug cap is the one closure that could carry it References

Permanently. On glass.

The requirement

Each container or product shall be marked with an identifying code permanently visible to the naked eye.

Two qualifiers, both doing work

Permanently, and visible to the naked eye. So not a mark that washes off and not one that needs a lamp or a scanner.

Which rules out several ordinary approaches

A sticker that peels, an ink that smears, a code readable only under ultraviolet light. All of those are marks and none is permanently visible to the naked eye.

On glass the options are narrow

19 of the 20 containers here are glass. Glass takes a permanent mark by etching, by ceramic ink fired on, or by a label with an adhesive that does not release.

None of which is a property of the jar

We publish material, capacity, neck finish, dimensions and case pack. Nothing about markability, and no coding or etching service.

The alternative in the text is the product

Each container OR PRODUCT shall be marked. Which for a solid product in a jar is not obviously available, and for some products it is.

And the code carries three facts

The establishment where the product was packed, the product contained therein, and the year, day and period during which it was packed.

In code, not in words

The requirement is to specify in code, so the mark is short and the key is held by the processor rather than printed on the jar.

Which is why it can fit on a jar at all

Three facts in a few characters. A plain date would take more room and say less.

And the period has to change often enough

Often enough to enable ready identification of lots during their sale and distribution. Which is a recall requirement expressed as a coding frequency.

So the code is a traceability tool

Not a label element for a consumer. Its audience is whoever has to identify a lot later.

The lug cap is the one closure that could carry it

11 metal lug or twist caps on this shelf. A metal closure takes an embossed or printed code in a way a glass jar does not.

References

21 CFR 114.80(b): "Each container or product shall be marked with an identifying code permanently visible to the naked eye." The section continues that "The required identification shall specify in code the establishment where the product was packed, the product contained therein, and the year, day, and period during which it was packed", and that "The packing period code shall be changed often enough to enable ready identification of lots during their sale and distribution." Paragraph (a)(4) provides that "Testing and examinations of containers shall occur often enough to ensure that the container suitably protects the food from leakage or contamination." law.cornell.edu

The Davis Pack Supply catalog, measured 19 October 2026. 203 rows: 20 containers and 183 closures, which is the second smallest container count in this library and the most lopsided closure ratio measured anywhere, at better than nine to one. 266 to 1,893 mL with a median of 473; 11 over a pint and 5 over a quart. 19 glass and 1 PET. 18 clear and 2 amber, which is the most monochrome shelf measured. 8 glass mason and paragon jars, 6 glass straight sided jars, 3 glass hex jars, 1 PET wide mouth container, 1 glass wide mouth short jar, 1 french square. Nine distinct neck finishes across 20 containers: 5 at 63TW, 4 at 89-400, 3 at 70-450G, 2 at 70TW, 2 at 70-400, and singles at 110-405, 70-450, 63-400 and 48-400. Liners on the closures: 53 heat induction seal, 28 F217, 22 pressure sensitive, 18 No Liner, 16 Plastis standard, 13 PE foam, 12 unrecorded, 11 Plastis pasteur, 9 foam. Buyability, a snapshot: 14 of 20 available, 6 not; 7 quote only; 19 of 20 full case only, with case packs from 12 to 144 and a median of 72.

Written from 21 CFR 114.3 and 114.80 and from the catalog as it stood on 19 October 2026. Part 114 governs commercial processors of acidified foods; home canning for a household is not commercial processing, and low-acid canned foods fall under part 113 which is a different and more demanding part not described here. Nothing on these pages tells anyone how to preserve anything, and cottage food laws, which are state law, are what actually govern a home preserver selling jars. There is no two-piece canning lid anywhere in this catalog.