Push the food into a ring

Because the middle is the last place the heat can reach, people say, and the ring removes it. Many discussions shape leftovers into a ring with the centre scooped out and say the plate heats faster and evenly; others describe the same shape independently, and one person lists bread, pizza and rice as where it helped most. Some people give the reason: heat enters from the outside of the food inward, and a ring has two outsides, so nothing is more than a rim’s width from an edge. One person points out the number: the waves only penetrate a centimetre or two, so a thick mound is heated at its heart by conduction from the outside, which is slow, while the outside sits in the field the whole time and overcooks — which is also why one person’s nachos come out with a burnt outer ring and barely melted cheese inside. Some people object that the tip is obvious, since there is no middle if you remove it; the answer given is the standing-wave one: the centre of the turntable is a stationary point that never passes through different energy zones, so it heats worst. One person objects that the trick fails when the plate is full, and admits they drop the power and add time instead, which is the other route. Many people mark the limit: it does not work for soup or anything liquid, because a liquid is already uniform — stir those, and read the water line above.

Yes, some people say, and others say it depends on your oven — and one person’s point explains both. Some people set the plate toward the rim of the turntable instead of dead centre, and some say small items belong on the outer ring; many others describe the same move in their own words. The reason people give is that a microwave has fixed hot and cold spots — standing waves — and the turntable’s job is to carry the food through them; a piece of food sitting on the exact axis of rotation goes round in place and never leaves its spot, so if that spot is cold, the middle stays cold. People in one discussion argue whether the centre is always the worst seat; what decides it, one person points out, is that the positions of the hot and cold spots depend on the oven’s cavity and how it was built, not on its geometric centre, so the centre is bad in some ovens and fine in others — and one person points out that unless the plate is very large or the food very small, some part of it crosses the axis anyway. Some people say the tips vary by model, and one says the claim that waves bounce harder at the edges is simply wrong. So people’s practical answer is to learn your own oven: one person maps its hot spots by heating something uniform — a hot dog, egg white, a layer of cheese — and seeing where it burns or sets first, and another measured the spacing of melted patches in chocolate or marshmallows with the turntable out. Two housekeeping lines from individual people: a turntable that is jammed or off its track heats unevenly, and a splattered interior absorbs energy that should be reaching the food, so wipe it. Some people had always centred their plates and never thought about it.

Both, or either, and people argue about which is the lazier. Some discussions heat in short intervals — thirty seconds or so — stir, and go again until it is hot through, which is also the Food Standards Agency’s advice for exactly the cold-pocket problem; one person lets the plate stand a minute at the end so the heat evens out, which the agency also names. Many discussions instead drop the power to somewhere between half and seventy per cent and add time — that method is the spine of the page on this site about leftovers going rubbery, and is carried there. People in one discussion argue between the two: one person on the low-power side says it keeps proteins from turning rubbery, and some people on the stirring side say that on most ovens ‘half power’ is full power switched on and off anyway, so stirring by hand during the off-time achieves the same thing without the wait. Some people object that stirring cannot reverse a portion already overcooked; the counter is that an ordinary oven cycles its power anyway, so stirring mimics the low setting without the time penalty. Some people say the low setting is simply too slow for them; one says stirring some foods makes a mess. Some people warn: any lower setting means a longer total time to get the same heat in — do not lower the power and keep the old time.

On most ovens, nothing subtle — it switches full power on and off. Some people point out that a ‘50 per cent’ setting on an ordinary microwave is the full beam for half the time; the conversations that use the low setting say the reason it heats more evenly is the pauses, during which heat spreads from the hot spots into the cold ones before more arrives. Some people say this is not true of every oven: models with an inverter — and, one person says, a minority of others — do turn the output down continuously, and softening butter or ice cream is where people notice the difference. People argue whether cheap ovens heat worse than dear ones or just slower, and settle on the technology mattering more than the price, and this page names no maker. People tidy, one person each, the folk physics that came up: microwaves do not cook from the inside out, and they do not work by resonating with water — the field twists the water molecules back and forth and the motion is the heat. One person says the turntable is not the only moving part in some ovens: a rotating antenna shifts the hot spots instead, which is why placement advice may not apply to yours. And one person calls a maker’s claim of an ‘efficient magnetron’ that ends hot and cold spots marketing, since the spots come from the cavity, not the tube. One person uses the defrost setting for the lunch they forgot in the freezer, which is a different page; many people enjoyed the conversation that used melted chocolate to measure the speed of light.

Steaming hot all the way through, the Food Standards Agency says — not warm — and if the middle is not, it is not done. Some people add a warning about the plate rather than the food: if the dish comes out much hotter than what is on it, or a mug develops fine cracks over time, the dish is either not microwave-safe or is holding water in its structure, and it will keep stealing the heat. One person warns square plates can jam against the walls and stop turning. What people did not provide, and the page names as gaps: how to form the ring for foods that will not hold a shape, what to do in an oven with no turntable — one person stands the plate on a small turning tray, carried as one person’s idea — and which power setting suits which food. Two gaps here are answered above by the regulators rather than by people, and the page marks them as its own lines: what to do about water that may have superheated, and how to tell food is safe after uneven heating. Pizza is not this page’s — some people here side with the oven over the microwave for crust — and neither is dry, rubbery reheating or rice; the leftovers page carries all three.