Do we need a new washing machine?

There’s been an on-going struggle between my wife and I over the washing machine. She has the strongly-held belief that our clothes are shrinking because the washing machine is faulty and so a new one should be purchased. I, on the other handy, am of the opinion that the washing machine is fine and clothes made from certain materials are prone to shrinkage.

I suggested that we should test the washing machine to see if it was heating up past the setting chosen. This didn’t get very far with my better half as:

  • it seemed hard to do – how can you measure the temperature inside a washing machine? (Imagine a look of incredulity for extra flavour)
  • it involved science – despite my wife having a GCSE Chemistry, the Scientific Method doesn’t get much of a look-in around here
  • it had the potential to prove the washing machine was not at fault – cue collapse of reality as we know it

So, after months of putting up with grumbling about socks that would now only fit a new-born, I have my chance. The house is empty. Let science begin!

Step 1

Find a thermometer that has a clear display and doesn’t mind getting wet. In my case, buy one from Homebase after finding that the one in the garden had broken after experiencing temperatures beyond its design parameters.

Step 2

Wrap the thermometer in bubble wrap (or similar) and cut a window in it so you can actually perform readings.

Step 3

Stick the thermometer to the inside of the washing machine door window. Make sure it is facing the correct way.


Step 4

Set the washing machine to the option to be tested.
Note – do not add washing powder or laundry to the washing machine at any point. That’s taking realistic simulation just a little further than is required.


Step 5

Start the washing machine and record the temperature shown on the thermometer at regular intervals.

Step 6

Prepare a graph of the results:


Step 7

Prepare conclusions.

As can be seen from the graph, there are three phases of the washing cycle. The temperature initially drops as cold water pours into the machine. Then the temperature rises to 40°C as the machine’s heater warms the cold water. Finally the temperature starts to cool as the heater is no longer in use. The water does not exceed 40°C and, in fact, is only at the requested temperature for a few minutes.
Note 1 – no data was recorded during the various drain, rinse, spin cycles that would normally follow the wash cycle. It is thought unlikely that warm water would be involved there.
Note 2 – I am not going to test all the different wash cycle options.

Step 8

Remove thermometer.

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