Thy coffee runneth over

Filed in Food & Drink, General

While at the first reading for a new stage play I'm involved in (「香水」 "Perfume" by Springtime Productions to run from May 2 to 11, 2005), a funny incident happened.

I wanted a cup of coffee. While there was a drip coffee machine there, it was turned off and I don't like drip coffee anyway. I'd prefer either instant coffee or coffee made with cappuccino machines. There was a water dispenser but for really good coffee; even instant coffee; boiling water is the best way to go. So I filled a mug with hot water from the dispenser and then placed it in the microwave oven for just over a minute.

After taking the mug out of the microwave, the water was still boiling but not in a normal way. The bubbles were smaller and more vigorous. Without another thought, I dropped a teaspoonful of coffee into the cup.

The reaction was instant. The water and coffee immediately foamed up and overflowed the mug, running down the front of the cupboard. There was a familiar click to the right of me. It was the sound of a fuse going off but I couldn't see a fuse box nearby and I couldn't understand why my coffee overflow might concern a power fuse so I ignored it.

Within minutes though, one of the people in the office was asking why the photocopier had switched off and I realised that a fuse really had gone off. Then while cleaning up the coffee, I discovered why. The coffee had run down the front of the cupboard and poured into a power strip just inside the front door of the cupboard. Apart from the power strip, there were also a couple of network routers, a PABX box, three power adapters and some telephone wiring. Somehow, I don't think they should have placed electrical equipment inside the kitchen cupboard.

Anyway, I unplugged the power strips, turned the fuse back on and everything was fine again.

The way that coffee foamed over was pretty incredible though. I remember reading somewhere that the bubbling is caused by expansion of air within the small crevices and cracks in the surface of the mug. The temperature of these bubbles can get extremely high and lead to the kind of reactions that I saw last night.

So, if you need to heat up water for a cup of coffee, using a microwave is fine as long as you don't leave the water in there for too long.


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3 Responses to “Thy coffee runneth over”
  1. 杜格拉斯 says:

    我好以係sixty minutes+睇過類似的東西,熱的傳播只有三種,分別係傳導、對流同幅射。一般煲水,用的是對流,水分子在底部受熱,跳動,有足夠能量脫離分子羣而形成蒸汽,以汽泡形式昇上頂層。 Microwave係以幅射形式將水係短時間加熱,水分子同時加熱,所以沒有溫差層,在底部的水份子即使大過一佰度,因為被水分子羣吸力所牵引,不能分解成汽体,一旦有外來物,例如茶匙,超熱水份子就會分解成汽体,一湧而上,情形就好似飽和的雨雲雖要塵埃而聚合成雨點一樣。所以用光滑的器皿時,要份外小心,不要把水加得太熱。

  2. Johnny says:


    About the air inside the coffee it is the CO2 inside the coffee bean when the fresh roast coffee is still fresh. This is the key to tell if the coffee is fresh or not, also the most important factor for creating crema for your nice good esspresso.

    Just a little tips for keeping your coffee bean fresh longer. Always purchase whole bean instead of grinded bean. This will help lesser air contact to the whole coffee bean due to that roasted coffee bean are very sensitive to O2 due to that it will oxidize. The whole fresh roast bean that could provide crema and plus good aroma is around 4-6 week. For grinded about 1 week only. If for playing esspresso, then you need coffee bean roasted within 2 week max. Due to that you would like your esspresso always with thick crema on.

    For me, still studying about the blending at present due to that I still could not blend a very smooth taste and texture esspresso.

    Happy Coffing,

  3. tngan says:

    Hi there,

    Take a look at this, folks:

    This is an in-depth explanation (with video clips) of how easy water could be superheated in an microwave oven, in turn, explosive behaviour of water could be trigger very easily by sudden motion. You folks were lucky not to have any physical damage to your hands or body. Superheated water/steam burns.

    Best Regards,