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17/05/2012 17:12 BST | Updated 08/06/2012 12:32 BST

# Perfect Sandwich Formula: Bakery And Boffins Team Up To Create Equation To Avoid Sogginess

A physicist has teamed up with a bakery to create the first ever formula for making the ultimate sandwich – with no sogginess.

It just looks like a mathematics nightmare to us, but we are assured this set of squiggles is the holy grail to making the perfect sandwich.

Dr Mark Hadley, a researcher at the University of Warwick's Department of Physics, explained: “In principle, this formula will also describe the butter seeping into the bread, particularly as it warms up because D can depend upon temperature.

Scroll down for an equation key, a poll and a gallery of "sandwich personalities"

"At the interfaces we have a physical and chemical reaction of absorption. The reaction rates depends upon the concentration in the air and the activation energy, Ea, and the area exposed to the air.”

While this groundbreaking collaboration between bakeries and boffins is no doubt a ploy to sell more bread, it seems these tips could actually work.

Thankfully, for those of us left flummoxed by the formula, Hovis, the bakery in question, has simplified things:

• Pressure: Don’t apply unnecessary pressure (the p(x,t) term) it squeezes out the water
• Freshness: The equations describe the deterioration with time due to slow diffusion of the moisture, so eat your sandwich while it is fresh
• Butter: Use a thick layer of butter, it is hydrophobic and keeps moisture away from the bread
• Moisture: Control the loss, or uptake, of moisture from the air into the bread, butter protects the top, crusts are good; they stop the edges drying out (φair < φbread) or going soggy (φbread < φair), wrap the sandwich tightly to keep air away from the underneath – but don’t squeeze it of course
• Temperature: Most equations are temperature dependent particularly viscosity and absorption rates, keep it cool to reduce the reaction rates.
• Bread: Use the right bread, a thicker slice like in Hovis British Farmers Loaf (fancy that!), has a greater resistance to dampness and can’t dry out so quickly either

The formula comes in the back of a survey that revealed the average Briton wolfs up to 240 sandwiches a year, equating to a staggering 19,200 sandwiches in a lifetime.

It may be a full 250 years since the fourth Earl of Sandwich is said to have demanded cuts of beef be brought to him between slices of bread so he needn't take a break from gambling, yet the bread-based snack has since become one of Britain's most popular and enduring culinary creations.

The survey of 2,000 Brits was commissioned by Hovis to mark a search for the Ultimate British Sandwich, celebrating British Sandwich Week and the launch of the brand’s all new Hovis British Farmers loaf.

Sarnie, butty, bap, cob, whatever you call it, Brits are sandwich mad with over a third (33%) choosing to chow down on one at least four times a week, often forming the backbone of many a lunch break.

When it comes to the "perfect" sandwich the majority of Brits agree it’s got to be homemade (62%), cut in triangles for optimum taste (45%), with the crusts left on (78%) and butter, not margarine, is the spread of choice (41%).

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Traditional cheese and pickle (16%) topped the fillings poll, closely followed by the classic BLT (12%). The quintessentially British cucumber sandwich came in last place with just 1% naming it their favourite filling.

Almost three quarters (71%) cite soggy bread as the top sandwich bug-bear along with the bread falling apart (38%) or it being packed with too many fillings so it becomes messy to eat (22%).

These butty faux pas have lead to over a quarter of Brits (26%) developing precise rituals when preparing their perfect sandwich.

Taking care to avoid sogginess, a fifth (20%) ensure the entire surface of the bread, right to the corners, is covered evenly with spread and a further tenth (10%) dry ingredients, like tomatoes, on a slice kitchen roll (9%).

Other sandwich quirks and foibles include: always using butter and mayo together (12%), using different utensils for every condiment (11%) and uniformly cutting all the fillings to such certain thickness (10%).

Click below to view a slideshow of “key sandwich personalities” as identified by bread-maker Warburtons last year.