How to make a drip-catching cup holder coaster for your car
Drip. Drip. Drip. Ugh. Why does condensation always have to interrupt a refreshing sip of an icy-cold drink with annoying drippity-drips? Physics, that’s why.It’s all thanks to a fundamental principle that governs our natural world. Energy can’t be created or destroyed, only transferred. Whoa. Let that sink in for a sec. So when a cold drink comes into contact with warmer air, water vapour in the air transfers some of its energy (heat) to the colder object. This loss of energy turns the water vapour from gas to liquid, which creates condensation. And here endeth the lesson in the first law of thermodynamics.
There’s no fighting the laws of nature. So here’s how to make a nifty absorbent coaster that fits into a car’s cupholder. It’s made of plaster, so you probs won’t want to carry it around with you, but it’s surprisingly absorbent and it will prevent your cupholder from turning into a swimming pool.
Here’s what you’ll need:
- Plaster of Paris (you can pick this up from an arts and crafts supply shop)
- measuring jug
- water
- spatula
- container (for mixing)
- plastic takeaway cup
Step 1
Grab that measuring cup, and crack open the bag of plaster. Well, cut it open. Neatly. You do NOT want to get plaster dust everywhere. And if you do, don’t try to wipe it up – vacuum it instead. The ideal powder-to-water ratio is 2 to 1, and about 1/2 cup of plaster powder is enough for your coaster. You don’t need Adriano Zumbo–like precision with the recipe here: close enough is good enough. So go ahead and tip the plaster into your mixing container.
Step 2
Fill your jug with 1/4 cup of water. Pour a little bit into the plaster powder while stirring. Keep on adding water in increments, mixing the whole time. Tap the side of the container as you go, to encourage any pesky air bubbles to the surface. You want to get rid of as many bubbles as possible because they weaken the coaster’s structure.
Step 3
Pour your plaster mix into your plastic takeaway cup, and tap the sides to get rid of any lingering air bubbles.
Step 4
And now we play the waiting game. Your plaster will take about 45 minutes to an hour to set, so set a timer and go do something else for a while.
Step 5
We hope you spent your time wisely. Pick up the plastic cup and place your hand underneath – it should feel warm. For some reason, plaster heats up as it sets. Yay, physics! Or is it chemistry? Anyway, you should be able to tip your plaster out of the cup mould. If it feels a bit stuck, don’t worry and don’t force it – just cut open the cup and ease it out.
Step 6
You’re done. Go forth and use your coaster. Marvel at how it soaks up the drips. It’s legit. Just make sure to give it a good airing every now and then. Plaster is porous and absorbent, so it tends to go a bit funky if it’s left in a confined space while moist. And by funky, we mean mouldy. Eww.
See it come to life in our carsales Car Hack video.
Related: Reusable coffee cup hot test
Related: Our Top five apps for kids in the back
Related: We taste-tested servo coffees to find out which one's the best for 2022
Please see our Editorial Guidelines & Code of Ethics (including for more information about sponsored content and paid events). The information published on this website is of a general nature only and doesn’t consider your particular circumstances or needs.
