Thanks for the input, y'all.
Funny about the bumping. The cloth under the bowl in the pot of water stops the buildup in the concavity.
For (I'll call it) a dipping jar, you want smoothe sides. Lid should be one piece, not childproof or have a paper or removable plastic lid insert. It is hard to clean childproof lids and inserts, and remove liquid extracts out from under the shoulder of a glass jar. Baby food jars are just the right size and one-piece lid construction, but I only know them with the shoulders. 1/2-1 cup mason jars are great for storage. Process needs at least a quart glass bowl and double boiler friendly.