Getting started

Two numbers and a mark

On this page13

The first number And above it is a different world So 4.6 is a boundary between regimes The second number is the gate The word to notice is equilibrium Which is the most useful thing on this page Then the container requirement Permanently, on a glass jar And the code has three required parts Which is more than a date The scope is narrower than the subject Then there is our own gap, and it is a single article References

4.6 is the line. And the container has to carry a permanent code.

The first number

A finished equilibrium pH of 4.6 or below, with acid or acid foods added, makes a low-acid food an acidified food.

And above it is a different world

Low-acid foods are any foods other than alcoholic beverages with a finished equilibrium pH greater than 4.6 and a water activity greater than 0.85. Those fall under a different and more demanding part.

So 4.6 is a boundary between regimes

Not a quality threshold. One side is acidified foods and the other is low-acid canned foods, with different rules for each.

The second number is the gate

A water activity greater than 0.85 appears in both definitions. Below it a food is outside both, which is why a dried product sits elsewhere again.

The word to notice is equilibrium

A finished equilibrium pH, meaning after the acid has distributed through the solids. A reading taken too early measures the brine rather than the food.

Which is the most useful thing on this page

The number is famous and the qualifier is not, and the qualifier is where a measurement goes wrong.

Then the container requirement

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

Permanently, on a glass jar

19 of the 20 containers on this shelf are glass. Glass takes a permanent mark by etching or by a label that stays, and neither is a property of the jar.

And the code has three required parts

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

Which is more than a date

Three facts in one code, changed often enough to enable ready identification of lots during sale and distribution.

The scope is narrower than the subject

Part 114 governs commercial processors of acidified foods. Home canning for a household is not commercial processing.

Then there is our own gap, and it is a single article

There is no two-piece canning lid anywhere in this catalog, and the shelf holds 8 glass mason and paragon jars.

References

21 CFR 114.3. Acidified foods are defined as "low-acid foods to which acid(s) or acid food(s) are added", which "have a water activity (aw) greater than 0.85 and have a finished equilibrium pH of 4.6 or below". Low-acid foods are defined as "any foods, other than alcoholic beverages, with a finished equilibrium pH greater than 4.6 and a water activity (aw) greater than 0.85." Part 114 governs commercial processors of acidified foods; low-acid canned foods fall under part 113, which is not described here. law.cornell.edu

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. Home canning uses a two-piece lid, a flat lid carrying a sealing compound plus a separate screw band. The 183 closures indexed to this group are 131 continuous thread polypropylene lids, 27 metal or aluminum CT caps, 12 dome lids, 11 metal lug or twist caps, 1 sealing disc and 1 metal overshell lid. None of them is a two-piece canning lid or a band, and a catalog-wide check finds none either. The shelf nevertheless holds 8 glass mason and paragon jars.

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.