I was talking about using mason jars for [the stresses encountered in] sous vide, not for canning. Exact same temperatures and almost exactly the same time (see following discussion), only the container would be different.. Mason jars are over engineered for sous vides. What that means is that, while they are not engineered for the purpose of sous vide cooking, the specifications for canning they were explicitly engineered for are far more demanding than what is required for sous vide. That's what I meant by "over engineered".
Canning is done at much higher temperatures than sous vides, none of which go to such high temperatures. Canning also creates pretty much of a complete vacuum in the space above the food and sous vides inherently can't create remotely as strong a vacuum. Sous vides can only heat air to expand and drive some (but not all) of it out. But canning creates steam and while a small bit of steam also remains in the jar, when it cools it reduces in volume much more than air (due to condensation) and thus leaves a much lower pressure. On both temperature and vacuum the stresses that mason jars are engineered to withstand are much higher than a sous vide can generate.
Canning is tottally different from sous vide processing but I was not talking about using a sous vide for canning. I was talking about using mason jars as containers for sous vide cooking.
Given the long periods of time involved, the difference in the heat conductivity of glass and of a plastic bag will not have any significant effect. Because mason jars are about 3 1/2" square, the heat will have to travel a bit farther to reach the center. But not as much as you'd think because as it goes inwards the width of the front shrinks (because the heat front coming in from both sides makes it along the diagonals. The result is that the heat front gets narrower and therefore travels faster. The result is that the time it would take the heat front to reach the center of a 1 quart/liter mason jar is about the same it would for a bag about an inch and a half thick. I'm just starting out in sous vide cooking but I believe that an inch and a half thick or more is very common for the contents of sous vide bags. Sous vide bags are so wide that the heat wave coming in from the edges have no effect on the time it takes the wave from the sides to reach the center (at least near the middle of the bag. So I'd argue that the time to heat the center of a mason jar would be about the same as the time for the center of a bag about 1 1/5 to 2 inches. IF I can ever get the low water alarm from blocking all attempts to cook I will actually test this (using temperature probes to the center).
Of course the downside from some points of view is that mason jars are totally reusable whereas plastic bags are usually used only once and therefore are a source of significant additional sales.
If I can ever get my low-water alarm from inappropriately going off and blocking every attempt at cooking, I will post observations on I will mason jars work for sous vide. None of the suggestions Enola support made in their reply to my first email worked and I'm still waiting for a reply to the email I sent them last weekend.
Does anyone have any suggestions about what to do about the low-water alarm going off despite the water level being only a half inch below the maximum line, the outlet pointed directly away from the wall of the container, there being a couple of inches of free space below the end cap and having tried multiple times resetting the ANOVA and using both the manual approach and two different smart phones (and deleting and reinstalling the app on both multiple times)? Both smartphones successfully connected and set both the time and temperature but, just as when doing it manually, a second or two after pushing the play button to start the low water alarm goes on and neither the circulation nor heat ever do. (also drying the disassembled Anova thoroughly (12+ hours in a very warm and dry room) between every attempt)