10 tried and tested YouTube lessons

You have seen YouTube tutorials. But do they actually work? SundayLife! tests 10 tricks being taught online.

1. Build your own air-conditioner

The weather is growing warmer but turning on the air-conditioning means a heftier power bill. So why not produce your own air-con unit? Get a large styrofoam box, cut a large hole in the lid and fit a fan in the hole so it can blow air into the box.

Cut another hole on the side of the box for cold air to escape. Then fill the box with bottles of solid ice, which you can make in your freezer.

Switch on the fan and enjoy your cheap "air-conditioning".

Does it work: Yes. If you cannot afford air-conditioning, this is a godsend. The air that comes out of the box can go below 20 deg C. Sit next to it and imagine you are in Genting Highlands.

If there is enough ice in the box - I used nine 1.5-litre bottles and 12 smaller bottles - your contraption might even be able to work about eight hours, enough to last you through the night.

But do not expect to cool your whole room with it.

The amount of air produced is too little to cause any major drop in the room temperature, so the best way to enjoy your DIY air-conditioner is to sit or sleep right next to it.

2. Use "AAA" batteries as "AA" ones with aluminium foil

If you do not have AA batteries, make use of AAA batteries instead.

Trick your device - be it a remote control, glowstick or Xbox 360 wireless controller - by padding the battery compartment with aluminium foil, which conducts electricity.

As long as you have enough foil to fill the gap between the batteries and contact points, your device should work fine.

Does it work: Yes, like a charm. I was initially afraid that my device - a Youth Olympic Games glowstick that I saved from 2010 - would explode, melt or suffer some horrible chemical reaction because the batteries required are of a different size.

Thankfully, that did not happen even after four minutes.

Now the next question: Can you pass off AA batteries as AAA ones?

3. Peeling garlic by shaking it between two bowls

Peeling garlic can be tiresome because it takes a long time and you have to pull the cloves apart and dig your nails into the edges to pull back the skin.

But some tutorials claim you can peel a head of garlic without getting your hands dirty. Better yet, you can do it in 10 seconds.

Just put the garlic between two metal bowls and shake it really hard.

According to a blog post by Mr John Rennie, a science programme, the garlic's dry, fibrous peel is relatively brittle, so all that agitation inside the shaking bowls helps to break the head open along the seams.

The clove itself is slightly slippery, which also helps it to slip out of the broken peel, he says on the blog.

Does it work: Yes. Within 10 hard shakes, the bulb of garlic had unravelled completely. Most of the cloves had shed their skin so I retrieved just the cloves and tossed the rest away.

4. Open a can without a can opener

Grind the lid of the can against a concrete surface - the rougher the better. Do this back and forth until you see liquids coming out of the can.

Most modern food cans are supposedly sealed with a rolled seam, meaning they can be easily opened once you grind through the edge of the seam.

In some videos, all you have to do after grinding is squeeze the sides of the can and the lid will pop open. In other videos, users pried the seams apart with a knife.

Does it work: Partially. It took me 10 minutes of constant scraping on a fist-sized rock before liquids started seeping out from my can of tuna.

But squeeze as I might, it was impossible to pop the lid open. Eventually, I managed to pry it open with a knife.

5. Cut a watermelon with a coin

Want to split open a watermelon but do not have a knife? A coin will work just as well.

Use a clean coin - a $1 or 50-cent coin is most ideal for its size - to make an incision in the side of the watermelon - half the coin should be outside the watermelon for easy "sawing".

Continue to extend this incision using a rolling action all along the fruit's circumference.

After this is done, you can pry the watermelon open with your fingers. Or, if there is someone you want to impress, karate-chop it.

Does it work: Yes, but it takes a lot of effort. Coins are not designed for sawing, and the fruit has a thick rind. To saw through it, I had to push and prod the coin with the base of my palm repeatedly.

You also have to be careful not to push too hard, or the coin will get buried in the flesh of the watermelon.

After you cut around the circumference - this took me 10 minutes - prying it open is a breeze.

No splatter, no fuss.

Perhaps due to the effort put in, the fruit might taste sweeter too.

6. Uncork a wine bottle with a shoe

The party has started and everyone brought wine. But in the midst of the excitement, nobody has thought to bring a cockscrew.

Well, everyone's wearing shoes, right? Slip the bottle into a shoe, resting the base of the bottle on the heel as if it were a foot. Then grip the shoe in one hand and the neck of the bottle in another and hit them against a wall or the side of a door. After a few minutes, the cork should start to pop up and you can remove it by hand.

Explaining the rationale behind this, James Wallace, a professor in the department of mechanical engineering at the University of Maryland in the United States, was quoted in food blog The Salt as saying that the impact of hitting the wall is transmitted to the wine.

The wine molecules then transfer the force all the way to the cork, making it pop out.

Does it work: Only on wine bottles with high shoulders. It does not quite work on Burgundy wine bottles with sloping shoulders, for example.

With the first type of bottle, 70 per cent of the cork was out after I pounded the shoe-cradled bottle against the wall 20 times.

With the second type, I bashed the shoe and bottle more than 50 times against the wall but the cork did not budge 1mm.

All it did was leave me feeling like a madman, with no alcohol to calm me down.

7. Remove scratches on a CD with toothpaste

Remove scratches from a favourite CD, DVD or any disc by rubbing it with toothpaste. First, squirt some toothpaste on the surface of the CD. Then, spread it all around the CD with your index finger in small circular motions, as if you were polishing a car. Leave the toothpaste on for about five minutes, then rinse the disc under cool tap water to remove the toothpaste.

After patting the CD dry with a piece of cloth, there should be no more scratches.

Does it work: Partially. The scratches on my 1994 Wakin Chau album Nothing Will Stop Me From Loving You were still there but they seemed to be less obvious. And yes, the CD still plays as well.

Warning: In the midst of all that rubbing, cleaning and drying, be careful not to introduce more scratches.

8. Hammering nails with a clothespeg

Use a clothes peg to hold nails while hammering. This saves your fingers from getting squashed by the hammer in case you are careless.

Does it work: Partially. This trick comes in useful during the first few hits.

After that, there is resistance from whatever you are hammering into, making it difficult to hold the nail firmly with the clothes peg to deliver subsequent hits.

The contact area between the clothes peg and the nail is simply too small.

After further research - okay, more surfing on YouTube - I came across other methods to hold your nail steady, such as placing it between the teeth of a comb or through a piece of cardboard.

Those seem to work better, going by the results in the videos.

9. Light candles with a strand of spaghetti

Candles in jars give off a cosy, romantic glow - is there anything more beautiful or perfect?. The problem is getting them to in lighting them. You cannot use a match or most lighters without burning yourself or having your fingers dipped in melted wax. And you probably don't have a taper candle lying around the house to get the job done without fuss. But you are likely to have some uncooked spaghetti, right?

Simply fire up a strand and you can send the flame to the bottom of any jar.

Does it work: Yes. A nifty household tip that can also be used for lighting your grill or kerosene lamp. Who would have thought pasta was so flammable?

You can look cool transferring the flame too, but you have to do so quickly as each strand lasts for less than a minute.

10. Remove scratches on wood furniture using walnut

Wood furniture is lovely but oh-so-prone to dents and scratches. Cover up these unsightly nicks using just one shelled piece of walnut.

Rub the nut over the scratch for a few seconds. The damaged areas should start to darken. Wait a few minutes to let the natural oils from the nut soak into the wood, polish the area with a soft cloth and, voila, the scratch is gone. Pecans, almonds and Brazil nuts will also do the trick.

Does it work: Partially. I tried this on an old wooden table at the office. The area with a scratch immediately began to darken once I rubbed it with a walnut.

Compared to some of the other tips I put to the test, this one took practically no effort at all. You can even eat some of the walnuts while waiting for the oils to seep into the wood - walnuts are known to help lower bad cholesterol.

But although the scratch became less obvious, it could still be seen from certain angles.

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