Cricket finds itself in a hot spot over silicone on bats

Silicone? In the clear. Owen Humphreys/PA

The Ashes series is already plagued by controversy over technology’s role in cricket. The latest allegations of equipment tampering haven’t helped. Australian TV station Channel Nine has reported some cricketers may be using silicone tape to evade detection of nicks by hot spot cameras. England batsman Kevin Pietersen has strenuously denied taping his bat with the tape.

So it seems the winning team needs to be master of not just bat and ball but also the decision review system (DRS). The question being asked by some is whether the DRS has encouraged new ways of cheating, rather than just new tactics.

There is a history of equipment tampering in cricket. Balls have, allegedly, been liberally polished with everything from hair gel to Murray mints in an attempt to affect they way they spin and swing. It was inevitable, then, that the bat would become the focus of attention eventually, and specifically how it could be “modified” to fool ‘hot spot’ technology.

Hot spot technology is basically a series of thermal imaging cameras trained on the batsman. The cameras detects infrared light given off by objects. The hotter an object the more infrared radiation it will emit and the lighter it will appear in the image. So when a ball hits a bat (or pad) the resulting friction and compression generates a hot spot that is picked up by the thermal imaging camera. This should immediately settle any arguments about whether a batsman did or did not hit a ball before it went on to be caught by some agile fielder. At least that’s the idea.

Insulate the willow

So what if you are a batsman rather prone to being caught out behind? You might think it’s be smart to mask the heat generated by ball hitting bat. Of course you’d then have trouble if you were wrongly called out LBW, because as Kevin Pietersen pointed out in that case a batsman would want evidence of a ball hitting the bat.

But assuming you’ve weighed up the pros and cons of bat tampering and decided to go for it, you will need to insulate the willow. Someone might notice a load of loft lagging wrapped around your bat, so something a little more subtle might be in order.

The big problem you have to overcome is that the hot spot cameras are pretty sensitive. They can detect temperature changes of just more than 0.017 degrees centigrade.

Luckily, you wouldn’t have to experiment much to figure out the best way to get around the cameras, because a group of students at the Massachusetts Institute of Technology (MIT) have done most of the lab work for you. They used high-tech robots and low-tech balls-on-sticks to test a range of bat tampering strategies. The trick was to find a coating for the bats that is a worse conductor of heat than air. This results in heat getting somehow trapped and not showing up as a hot spot.

The first option was to use Vaseline, which ex-England captain Michael Vaughan once suggested Indian batsman VVS Laxman may have slathered on his bat. According to the chaps at MIT this would have made things worse for Laxman. This is because vaseline conducts heat better than air and so would make hot spot images sharper. That is, unless he applied a good thick (and obviously visible) layer of the stuff.

The second option is a application of silicone spray. This seems like a good idea, not because it makes the bat smoother and thus reduces friction (as suggested in the silicone tape allegations), but because silicone is a very poor conductor of heat. So it acts as an insulating layer, keeping the heat in the bat.

It’s quite clear in the MIT video (see 6:45 onwards) that silicone does the trick. It completely masks the hot spots.

Maybe not

So job done? Not really. With the silicone coat, the bat now appears completely black to the thermal camera and nothing at all registers when the ball makes an impact on its surface.

In fact, with the use of the thermal cameras, the doctored bat is so obvious that any batsman using it may as well have written “I’m a raving cheat” across his helmet with silicone spray. So our hypothetical batsman might be able to cheat hot spot technology, but it’s not going to fool anyone for long.

And the same goes for any silicone tape that may have been applied to the edges of Pietersen’s bat. It will do the trick, but it would also be obvious as a black strip along the length of the bat, which of course there is no sign of.

Used correctly, systems such as the DRS can undoubtedly be used to help umpiring decisions, and in this case it can just as easily be used to defuse a cheating row. There’s no sign on the thermal cameras of an insulated bat, so, despite what some Australian media claim – including the Sydney Morning Herald – it looks like Pietersen (and others) are in the clear.