Espresso · froth · Hack · latte · Technique · Zhng

Milk pitcher built-in thermometer mod

Remember how  we started frothing earnestly with thermometer hooked onto the milk pitcher every-time? And then we progressed to a stage where the the thermometer is no longer necessary because we have learnt to recognize the temperature with our hand? It is also an excuse because the thermometer creates more hassle and not forgetting the extra clean-up needed.

What if there is a cheap solution to have the thermometer always available that is dish washer proof, as accurate and precise as digital thermometer and requires no battery?

I have been experimenting with liquid crystal temperature strips for the past 9-months and I am happy to share the details in this post.

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These are the reversible liquid crystal strips in self-adhesive form which are suitable for the milk frothing temperature. And they cost only about ~SGD2 each from RS-Online. The following list includes the links to the strips shown in the photo above, the product numbers and the measurement ranges.

Since the liquid crystal strips are self-adhesive, it can be stuck onto the external surface of the pitcher and you are ready to roll (the milk). A strip which has been stuck on one of my pitcher is losing its adhesiveness due to daily exposure of water from the cleaning, but this is not an issue since it is low-cost and can simply be replaced with another strip.

It can also be made more wash-proof by applying a layer of clear epoxy over the strip. I have gotten the following epoxy (no-VOC) and ‘spatula’ from ArtFriend. Do check the temperature rating of the epoxy if you are planning to use a glue other than the one shown here.

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The 906-4609 liquid crystal strip protected by a thick layer of epoxy. Not professionally done I admit!

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The accuracy of the liquid crystal strips are affected by the height of the water line. The following photo illustrates the minimum water line required to accurately measure 55°C-80°C.

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The following photo shows the pitcher with the 286-169 and 286-175 liquid crystal strips cut and merged to show one continuous sequence of reading from 50°C-80°C.

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Using a digital thermometer as the base of comparison, this shaky video demonstrates how fast and accurate the liquid crystal strip reacts to the changes in temperature. The milk and pitcher were chilled before steaming, and the steamer was shut off when the digital thermometer reads 71°C.

And there you go, cheap and easy mod that can be easily accomplished by anyone! I have no idea how long the strip can last. It has been accurate for the past 9-months. I would love to hear your experience with it too 🙂

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