Microwaves tend to come in 2 types, ones with a rotating plate and ones without. Assuming everything else is equal about a microwave does rotating the food assist with the reheating?
Yes, it does. Without the plate you will get hot and cold spots where the waves interact. If you don’t have a rotating plate you should be manually rotating the food, unless there’s some new tech I’m not aware of.
Tray-less microwaves have a spinning metal “stirring fan” below a plastic floor you set your food upon to mix the bounce path the microwaves take. Since they expose fewer moving parts to the end user they are easier to clean and more resilient making them a good option for commercial / high volume settings.
Interesting, thanks!
I haven’t seen one for sale in a few decads though. Where can I get one?
The keyword is “flatbed”. They are well available. Mine is a noisy Whirlpool MWF 421 BL with a glass floor and door, coarse pulse width modulation fractional power (overheat and cool down alternating), and a grill that doesn’t work at the same time with the microwave (heat first, then brown). I’m looking for a quieter one with inverter for real fractional power.
Try a specialist catering supplier. They’re not cheap though.
A microwave works by bouncing microwaves around the interior. Since the shape of the container doesn’t change neither will the path that the bounced waves take. This can lead to hotspots in what you’re reheating.
To mitigate this you have a few options:
- move the food around in the container so that different parts pass through different hotspots over time (this is what a tray does)
- interrupt the microwave path via a “stirrer fan” that sits below the microwave floor (this is what tray-less units use)
Both approaches redistribute the hotspots to maximize even heating. The efficacy of either approach will come down to the specific design of either unit, but a tray-less unit can be easier to clean, and with fewer moving parts exposed to end users can be a good option for commercial/high user count settings.
Each design accomplishes the same task of relatively even heating with few hotspots.
As others have said, microwave ovens create standing waves with regions of higher power (hot spots), which unevenly heat food. If you want to see this for yourself, Scientific American has a kids project for measuring the hot spots in a microwave using chocolate or marshmallows. There’s also a bunch of videos on YouTube of people essentially doing this same project.
As long as you don’t put it in the center, yes.
I always forget that. Instinct is to put things in the center.
Even in center it will work given that the time you are heating isn’t tiny.
The center is the least optimal place for even heating.
But nothing really lies in the center. If you put a pie dead center in the microwave, 99,99% of it wouldn’t be in the center. Even the center of the turntable isn’t in the center of the microwave.
You’re missing the point.
The issue isn’t just about the physical center of the plate or the microwave itself. The key point is how microwaves heat food unevenly. Microwaves create standing waves, which result in hot and cold spots. The center of the microwave tends to be one of the cold spots, regardless of where the turntable is.
When the plate rotates, the food gets exposed to more areas where microwaves are stronger, leading to more even heating. However, if you place something directly in the center, it’s less likely to move through those stronger areas, which is why the center tends to be the least optimal spot for heating evenly.
It’s not about whether 99% of the pie is centered—it’s about how the energy is distributed within the microwave.
I know what you’re trying to say but it just isn’t that simple.
With my mother’s 40 year old microwave the center is the worst spot but mine is just different. How the energy is distributed will differ from device to device.
You can’t know where the standing waves occur so you’ll just have to experiment but I’ll agree that the safest guess is to put your food slightly off centered on the rotating disc.
No you’re completely missing the point.
It’s about how much of the volume the object can take up due to the plate spinning.
If it’s perfectly centered, it only takes up its own volume. If it is off to the side it swoops around and takes up the volume that it takes up but on every quadrant of the plate as it rotates
I don’t have any interest in discussing this with you any further
It makes the heating more even. The microwaves aren’t uniform inside so rotating helps even things out.
I had a microwave that moved the plate side to side which worked really well for heating anything solid, but heating liquids usually resulted in a mess.
Do they still make non rotating microwaves?
Yes, commercial and maybe some premium microwaves can achieve the effect of the turntable by more hidden means.
Though, I don’t know if they still make cheap microwaves without any hotspot mitigation whatsoever.
The keyword is “flatbed”. Plenty around.
Here’s a (trained electrical masters) putting metal in a microwave. I don’t remember if its this or another of his microwave videos in which he warms up the cardboard box and looks at it with a thermal camera.
Or maybe it was a veritasium microwave plasma video where they show it i can’t recall
At least one brand now has a newer design that rotates the microwaves themselves to better distribute the energy. It’s a bit pricier than the standard models.
I only use the most expensive of microwaves that rotate the actual causal reality of the earth-itself around the microwave.
I had a square one so without a rotating plate, IIRC it was the microwave emitter that rotated instead. If that is plausible, I sort of doubt it a little now.
