Labor senator Helen Polley has raised eyebrows with an unusual technique for cooking hardboiled eggs.
In an “egg hack” video posted to TikTok, the Tasmanian senator completely wrapped a raw egg in aluminium foil, submerged it in a plastic container of water, and said she microwaved it for six to seven minutes for a hard boil.
Senator Helen Polley cooks eggs in her microwave by covering them in *foil* and submerging them in water pic.twitter.com/LLo8ik1OKn
— casey briggs (@CaseyBriggs) April 13, 2023
“Every time I’m cooking them in my Canberra office … everyone’s just really taken aback, saying: you can’t put foil into the microwave!” Polley told Guardian Australia.
“This is something I’ve been doing for probably 25 years, if not longer, and I’ve never had a mishap.
“I didn’t perfect this,” the senator added. “It was my mother-in-law who demonstrated it to me many years ago.”
Polley’s technique runs counter to general wisdom to avoid putting metal objects into microwaves. So how has the senator managed to avoid setting off fire alarms in Parliament House?
Metal heads
Microwaves are a frequency of electromagnetic radiation that work primarily by heating up the water molecules in food.
Metals, on the other hand, absorb much less of this radiation, and tend to reflect most of the microwaves away from their surface. It’s why microwave ovens are entirely lined with metal, with a thin metal mesh embedded in their front doors.
Technically, a microwave oven is an example of what’s known as a Faraday cage, according to Prof Zdenka Kuncic, a physicist at the University of Sydney. “It’s preventing the electromagnetic radiation from seeping outside.”
Exposing a metal object to microwave radiation will mean the metal absorbs some of it, but can also lead to electrostatic sparks, particularly if the metal is thin, pointed, or has sharp corners, as in the case of crumpled aluminium foil.
“You really only need a very thin layer of metal to cause sparks,” Kuncic said. “Generally speaking, even if you had really thick metal, the absorption and the sparking would really only affect … the outermost layer.”
US guidelines suggest aluminium foil can be used in the microwave in certain circumstances, such as using small pieces of smooth foil to “shield” parts of food so they don’t overheat.
Kuncic said in Polley’s case, the water surrounding the egg-in-foil served two purposes. “One is to insulate the electrical sparks from the foil – to prevent them from flying around. The second thing is to actually help cook the egg, which would otherwise not really cook because it’s got foil around it.”
“Microwaves work by jiggling around the all the water molecules. When you’ve got a little tub of water in there, it’s heating up the water,” she said. “The egg would be to some extent insulated by the foil directly from the microwaves, [but] the water surrounding it will heat up and that heat can get transferred through the foil into the egg to cook it.”
Dr Nathan Kilah, a senior lecturer in chemistry at the University of Tasmania agreed: “The water there is basically preventing the aluminium from arcing [sparking] in a way that it normally would.”
Eggsplosion risk
In 2019, a contributor to a Woolworths community site detailed the same technique as Polley’s, but one of the respondents, who did not submerge the egg in water, warned: “Last year I blew up my new $600 microwave doing this.”
Foil aside, whole eggs with shells are prone to explosion when cooked or heated in the microwave.
One case report published in the British Medical Journal, titled “Penetrating ocular trauma from an exploding microwaved egg”, details the plight of a nine-year-old girl who reheated an already boiled egg with an intact shell “at full power for about 40 seconds”.
“The heated egg was removed from the microwave oven and placed in a bowl. Around 30 seconds later, as she was carrying it to the dining area, the egg exploded with part of it hitting her right eye and face,” the report noted, going on to detail the eye surgery she subsequently required.
Kilah explained: “The water in the egg turns to steam, and … it can’t escape from the shell, which leads to it exploding. The air space in the egg would also expand with the heat.
“Adding an egg directly to boiling water can make it crack – so the air is expanding against the shell, but it’s not so dramatic, as the internal egg temperature doesn’t warm up as quickly.”
A safer option for those who are insistent upon cooking their eggs in the microwave would be to crack the egg first and poach it in water.
