Mentos eruption

Friday 29th May 2015

I've seen some great Mentos and Diet Coke eruption videos on Youtube, and I've always wondered whether other soft drinks work too.

Here comes the science.


The Mentos eruption works just as well with any kind of soft drink, but it doesn't work with Fruit Mentos or sparkling water. It will be more explosive with powdered Mentos because of the increased surface area.


12 bottles of various soft drinks and 12 packets of Mentos were bought from a local supermarket. The bottles were opened and a packet of Mentos (eight sweets) was dropped into the bottle using our patented delivery mechanism (an empty Berocca tube).


Screenshots were taken from the video at peak foam. The images were scaled to make the bottles the same size and the eruptions were plotted on a pretty graph.

The average heights of the eruptions were calculated. Note that Coke Life and sparkling water were not included in either of the diet or regular averages.

  • Average height: 26cm
  • Average diet drink height: 26cm
  • Average sugary drink height: 34cm
  • Average Tesco drink height: 32cm
  • Average Coca-Cola drink height: 28cm


Our experiment shows that soft drinks containing sugar can produce higher eruptions than diet products, and that it does work with Fruit Mentos but not with sparkling water. Powdered Mentos do not produce a higher plume than whole sweets.

Sadly our delivery mechanism left a lot to be desired, and to be honest the height of the eruption a lot to do with how many Mentos were delivered into the bottle before it started foaming.

Wikipedia explains the science behind it. The world record for the most number of simultaneous Mentos and Soda fountains is 4,334 bottles at once!

Thanks very much to my awesome cameramen Jay-yoh and K-Herb.



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Why I don't drink

Friday 22nd May 2015

It's lemonade, I swearIf you're pushed for time, the short answer is that I've just never really liked alcohol.

The first time I remember getting drunk I was 10 or 11 and my parents let me have a snifter of Pomagne that I'd won at a school fête (hey, it was the 80s).

It made me feel dizzy, then I fell off my chair and threw up.

The second time I remember getting drunk was at a friend's house when we were maybe 13,

I got slaughtered and puked in his garden and passed out. I have a hazy recollection of my friend's dad standing over me looking vaguely concerned (80s again).

Can you see a pattern here?

Therapeutic index

Let's talk pharmacology for a minute. The therapeutic index of a drug is the gap between the effective dose and overdose.

The best drugs have a very large therapeutic index: the surgical painkiller Remifentanil scores 33,000:1, which means that you can overdose by 33,000 times the effective dose without any toxic effects. That's pretty safe.

THC, the active ingredient in cannabis, has a therapeutic index of 1,000:1 which is why there are no recorded deaths from smoking too much weed.

Some drugs have much smaller indices: paracetamol is about 20:1 and ethanol (the chemical in booze) is just 10:1. Ten times as much alcohol as it takes to have an effect is enough to produce a toxic effect - not just making me feel a bit groggy, but causing damage to my body.

This is why it always makes me feel sick, I find it too easy to go from merry to wasted in a couple of drinks.

"Relaxing" with a bottle of wine

I originally only planned to stop drinking for a month, joining friends on a Dryathlon in January 2013. I didn't do it to raise money, just for the experience.

I quickly learned some things about myself - if I'd had a hard day at work, or a stressful meeting, I'd automatically reach for the whisky and then remember I wasn't drinking that month.

It didn't exactly scare me, but made me aware that I was using alcohol to stabilise myself. As the month progressed I found myself doing it less, but noticed it more and more in other people. Some Facebook friends only ever post about how they've had a hard day and are now relaxing with a bottle of wine.


By the end of the month I'd noticed a really important change - I was sleeping much better. I'd always suffered from really horrible nightmares, I would regularly wake up covered in sweat, heart pounding, and with a full bladder.

I kept a log of my nightmares for a while, which included:

  • 28th Jan: Francis was killed and eaten by Gila monsters
  • 19th Feb: My fingers were being eaten by rats
  • 10th Dec: Shot and killed two men

This completely stopped during my month off, and it's never come back. People have suggested that my body was waking me up to go to the toilet by making me have a nightmare, which is apparently a recognised phenomenon in children, but I've been unable to find any quality research backing it up.

Peer pressure

For the first month, when I told friends I was doing Dryathlon they didn't seem bothered. But when I didn't start again in February I got a few funny looks. Friends who love their beer looked slightly worried and ask me to this day "so are you still not drinking?". Kat's grandfather was horrified when I turned down his very expensive red wine at lunch the other day.

If there's one thing I've learned, it's that I can have just as much fun sober as I ever did drunk, and I don't have a hangover in the morning. In fact for the first time ever I've learned that there's a big difference between going to bed lashed and going to bed late - I can go to bed sober at 2am and feel fine the next day!


I've really noticed an improvement in my health since I stopped drinking. I'm fitter, I catch fewer colds and I've lost weight (although this is not a scientific survey). A pint of Carlsberg Export is 244 calories, so if I sank eight pints a week, I was consuming an extra day's calories each week.

I'm happier

I don't know if there's a simple term for what I am now, but one thing I'm not is teetotal. I've had five or ten drinks over the last few years, and I've been thoroughly smashed twice.

I'm really not trying to persuade you to stop getting drunk, and I'm really not judging you if we hang out for an evening and you're incapable of standing up or constructing a sentence by 10pm. What I am saying is that I'm happier not drinking.

If you're going to the bar I'll have a lemon, lime and bitters please.

At what age did you first get drunk, and on what? Let me know in the comments!


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Metal casting furnace

Friday 15th May 2015

My aim this year is to cast my own bronze sword, and to do that I need to melt the bronze. I just made a bucket furnace that's good enough to melt copper and tin, the metals in bronze alloy. My furnace is based on the Mini Metal Foundry on Youtube.


Here are ingredients to make it.

  • 10 litre metal bucket - the body of the furnace
  • 5 litre plastic bucket - to make a void in the centre of the furnace
  • 15 litre plastic bucket - to make a lid for the furnace
  • Tin can - to  make a void in the centre of the lid, to release pressure
  • Two metal hoops - these will become handles for the lid
  • 1 inch steel pipe - this is the air intake for the furnace
  • 25kg dense castable from Castree Kilns
  • dog - serves no useful purpose


Making the lid

First of all I made the lid, with 10kg of the dense castable and 1.3 litres of water, mixed thoroughly.

I set the tin can in the centre of the mix and sunk the handles into it. Then I let it cure for 48 hours. The dense castable material is strange stuff, it's very dry and at first I didn't think it was going to cure. But 48 hours later it's hard as rock.


Making the body

I needed to make a hollow body for the furnace, so I used a small bucket filled with water in the centre to make the void.

I used 15kg of dense castable with 1.95 litres of water, which pretty much filled the bucket. I let this cure for 48 hours as well, and spent several hours cleaning all the gack off the kitchen table, floor and ceiling.

The mistake I made here was spilling some of the dense castable into the white bucket in the middle. When I poured the water out, there was a 2cm layer of rock hard material in the bottom - turns out it sets underwater just fine! I hacked it into little pieces and pulled it out with no problems.

Once it had set, I used a hole saw to cut a piece out of the side, and fitted a steel pipe to force air into the furnace. This is hooked up to Kat's hair dryer - shh, don't tell her!

Here's the finished furnace, the next step is to fire it up!

Here are some pics of the first time I lit it up, to melt some aluminium as a test. Aluminium melts at a much lower temperature than bronze, so it's easier to work with and cheaper.

The crucible is made of ceramic bonded clay graphite, it's a Salamander A2 from Castree Kilns. It's rated to 1600°C. The original instructions I followed used an old fire extinguisher, but I've been told that these are quite unreliable and prone to sudden failure.

Finally here's a quick video of the furnace in action:

The next step is to make a sword template out of wood and then cast it.

I've no idea how that works but it's going to be fun finding out!


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How old can I look?

Friday 8th May 2015

I must admit I'm not a fan of the selfie, but in the interests of science I took a bunch of photos of myself to see how Microsoft's website reacts to different expressions. How old can I make myself look?


From above

Fair play to Microsoft, they got this one spot on - I am indeed 39. Lucky guess?



I've read articles saying that the best way to get a young score is to pull a neutral expression that minimise any lines on your face. I can add a decade by looking angry.



Result! An extra 16 years by looking confused.

Kat always says I look like Beaker from the Muppets when I pull this face. Sadly the website couldn't tell me how old Beaker looks:



I can only hope I look this good at 48.



I'm pretty sure I've got a face. Maybe it's too old to detect.


Tongue out

Bit surprised by this one, is this what 52 year old men do?


Black and white

This is the same picture that scored me 39 at the top of the page, now scores 49 in black and white. What's going on there? Maybe it thinks that the world used to be in black and white and so anyone with a black and white must be old?



I wondered how Photoshop could change my age, if black and white adds ten years. Going from least to most saturated (left to right) takes me from 48 to 44, but at the extremes it couldn't detect my face. Young people are more colourful, obviously.


Me too

Finally, I thought I'd try putting multiple copies of myself in the picture and see if it gave the same answer:

I think we've learned something important here: needs more work. In a row of six identical colour photos of me it can only spot faces in two of them and gives them ages of 44 and 51, and in black & white there's an 8-year age difference between six identical photos, from 40 to 48.

To look as old as possible, I need to look confused. Have a go yourself and see how old a score you can get, then leave a comment with your tips for looking old!


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Who should I vote for?

Friday 1st May 2015

I decided to run a competition to find out who I should vote for in the general election. Did you know that we're having an election next week? Maybe you hadn't noticed.

I can't remember who I voted for last time, it was either the Greens or the yellows. One thing I do know is that I've never voted for the winning party nor had my choice of MP elected.


Choosing a colour

First I took a number of tests to see who I should vote for.

The fascinating Political Compass has a very thorough test that plots your politics on a grid (see image), and put me nearest to the Greens but miles away from all the other parties.

I went through the extremely complex Vote For Policies website, which gave me a 50/50 split between Green and Labour.

I took the poll at Votematch and I scored 82% for the Greens, 73% for Labour and 66% for the Lib Dems.

I also took the quick I Side With poll, which gave me 97% Plaid Cymru (?!) 95% Green, 94% Lib Dem and 92% Labour.

Finally, just to make sure, I took the very quick Tickbox poll, which told that I should be voting Green.

So far, so good - it looks like I should vote Green.

However they're almost certainly not going to win here (in 2010 they got 1.7% of the vote) so is there any point voting for them?

So I thought I'd put all the candidates to the test and score them.


Our candidates

Here in the constituency of South East Cornwall we've got six candidates, with William Hill's odds in brackets:


My questions

I thought it would be interesting to see where they stand on issues that are important to me, so I emailed all of them with three questions covering, local, national and global issues.

I did this before the 2010 election with three different questions that were open-ended. I got a very poor response so these questions are much quicker with simple yes/no answers.

Hi [first name],

I live in Lostwithiel, in South East Cornwall where I believe you're standing in the general election in May.

I haven't decided who to vote for yet, so if you've got a few minutes I'd appreciate your thoughts on the following questions:

  1. Do you support plans to build the UK's first spaceport in Cornwall?
  2. Do you support Dignity in Dying's campaign to legalise assisted dying in the next parliament?
  3. Do you think we're doing enough to tackle climate change around the world?

If you'd rather speak to me, call [my number] any time.

Best wishes,


I'm going to score them on: how quickly they respond (3 points for the first to reply, decreasing by one each time); the way in which they respond (4pts for a long call, 3 pts for a short call, 2pts for a long email, 1pt for a short email, 0 if they don't reply), and how much their responses correspond with my views (0, 1 or 2pts per question).


Andrew Long - Mebyon Kernow

Andrew replied within quarter of an hour of me emailing him, and gave detailed, well-reasoned responses to my questions:

  1. He's in favour of the spaceport, as well as continued development of the AeroHub at Newquay Airport.

  2. He's in favour of assisted dying provided the proper safeguards are in place. He pointed out that this is his personal view, as Mebyon Kernow doesn't have a party policy on the issue.

  3. He doesn't think we're doing enough to tackle climate change, he thinks the government should be encouraging wave energy and geo-thermal as well as existing renewables, and he believes that we need to protect our land for the production of food.

So 3pts for replying first, 2pts for a long email, and 6pts for his answers to my questions.

Total: 11 points


Phil Hutty - Liberal Democrats

Phil called me within an hour and a half of receiving my email, and we had a very interesting fifteen minute conversation. He's very bright, enthusiastic and passionate about Cornwall. I'll paraphrase his answers:

  1. We didn't talk much about the space port as he didn't know too much about it, but more generally about the Cornish economy. He'd like to make Cornwall more appealing for business by dualling the A38, adding a second railway line into the county and cancelling the Tamar Bridge toll.

  2. He was in favour of assisted dying, providing the right safeguards are in place.

  3. He thought we should do more to tackle climate change. He mentioned some interesting new technologies that can replace fossil fuel-generated power, and said that he sees wind and solar farms as an interim step for power generation until better technologies come along. He said that he was in favour of building new nuclear power stations if they're needed, to reduce our CO2 output.

So Phil scores 2pts for replying second, 4pts for a long call, and 6pts for giving answers that agree with my opinions.

Total: 12 points


Declan Lloyd - Labour Party

Declan responded in a couple of hours with a short email. To paraphrase his answers:

  1. He thinks Cornwall is the best place for a spaceport and will bring quality employment

  2. He agrees with people having the right to die with at their own time, with the correct oversight.

  3. He thinks we're not doing enough to tackle climate change, and opposes mining for shale gas.

So Declan scores 1pt for replying third, 1pt for a short email, and 6pts for giving answers that agree with my opinions.

Total: 8 points


Bradley Monk - UKIP

Bradley responded within about four hours. He sent a long email with detailed replies to my questions. To summarise his reply:

  1. He fully supports a Cornish spaceport and the highly paid jobs it will bring to the county

  2. He fully supports assisted suicide, having been personally affected by the issue

  3. While he's skeptical about the human involvement in climate change, he agrees that we need a wider mix of energy generation, but doesn't think wind and solar are the sole answer.

If I'm being honest I was surprised at how eloquent and well-reasoned Bradley's answers were, and I was expecting his answers to include references to the EU and immigration, which they did not.

So Bradley scores 2pts for a long email, and 4pts for giving two answers that agree with my opinions.

Total: 6 points


Martin Corney - Green Party

Martin sent me an email reply within a week, here's a summary:

  1. He supports the spaceport because he loves technology and sees it as part of a Green world.

  2. He is against assisted dying because of the risk to the vulnerable.

  3. As you'd expect, he doesn't think we're doing enough to tackle climate change and believes that fossil fuels should stay in the ground.

So Martin scores 2pts for a long email, and 4 pts for his answers to my questions.

Total: 6 points


George Trubody - Independent

George replied with a long-ish email after week or so (after I chased him), his replies were:

  1. He would welcome the investment and jobs that it a spaceport would bring. He made the point that Newquay Airport is owned by Cornwall Council who have always struggled to make it profit, so any new business would help.

  2. He didn't know enough about assisted dying to comment.

  3. He doesn't think we're doing enough to tackle climate change.

So George scores 2pts for a long email, and 4 pts for his answers to my questions.

Total: 6 points



Sheryll Murray - Conservative Party

Unfortunately Sheryll didn't reply to me, so I'm unable to give her a score. This is a shame, because everyone says she's a nice person and a good MP, and because I really wanted to back the winner for once.





I've learned that I'm a natural Green voter, but this year I'm voting for Phil Hutty, our Lib Dem candidate.

Sadly too late for this election I discovered that it only costs £500 to stand as a candidate in a general election, so I've added it to my i-Spy Book Of Life for the next election in 2020!

I hope I can count on your vote.



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