zombie or no
if you have autodefrost/frost-free then the heating may affect the cube quality near the walls.
How did you determine that? I assume when the status of your ice cubes changed, your called the water company and asked about the water source. Anything else would be guessing.
I’ve actually never had a fridge with an ice dispenser (and I just recently bought one a few years ago), and neither have my parents. It’s not that uncommon to not have an ice dispenser.
When I was a small boy way back in the early 50s, we were living in Sierra Leone. My father was extremely proud of the fact that he managed to ‘liberate’ an American style fridge from somewhere and I still recall it occupying a large part of our kitchen.
Although it had two doors, it had no water dispenser so since all our water had to be boiled, the main contents were beer, of course, and water which we kept in gin bottles, because they had snap tops.
We have a silicone tray that makes big gummy bear ice cubes for the kids. They don’t really stick, per se. You do have to kind of poop them out one by one by pushing in the back, though. We’ve never had one break I don’t think…
There are a number of factors involved with ice shattering, and so you get lots of different answers.
First, freezing rate: Ice is less dense than water at 4°. If the ice freezes fast enough to prevent expansion, then tension builds up inside the ice, and it is more likely to fracture. Freezing rate is determined by the temperature freezer load, the freezing cycle, and the starting temperature. It can also be influenced by …
Second, impurities: particulates, dissolved gases and rough surfaces can act as ice nucleation points, speeding up ice formation (particularly round the edges and over the top, preventing expansion as the centre freezes). Dissolved salts can reduce freezing point. Dissolved air will be forced out of solution, causing cloudy bubbles and adding nucleation points. This combination of factors interacts with the freezing rate to determine the level of internal tension, and thus the likelihood of fracturing. It should be added that very pure water is also prone to supercooling, where no nucleation points are available and the water stays fluid well below the freezing point. When is does freeze, it can snap freeze and will have considerable internal stress.
So - thin icecubes are less likely to fracture than deep ones. Pure water may be better than non-pure (but not too pure). Slow freezing should be better than rapid freezing. YMMV.