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The Guinness "widget"

Curiosity got the best of me tonight and I decided to cut open a can of

Guinness in order to have a closer look at the "widget".


From Wikipedia, the free encyclopedia


The "floating widget" found in cans of beer is a hollow sphere, 3 cm in diameter. The can is pressurised by adding liquid nitrogen, which vaporises and expands in

volume after the can is sealed, forcing gas and beer into the widget's

hollow interior through a tiny hole - the less beer the better for

subsequent head quality. In addition some nitrogen dissolves in the beer

which also contains dissolved carbon dioxide. The presence of dissolved

nitrogen allows smaller bubbles to be formed with consequent greater

creaminess of the subsequent head. This is because the smaller bubbles need

a higher internal pressure to balance the greater surface tension, which is

inversely proportional to the radius of the bubbles. Achieving this higher

pressure is not possible just with dissolved carbon dioxide because the much

greater solubility of this gas compared to nitrogen would create an

unacceptably large head. When the can is opened, the pressure in the can

drops, causing the pressurised gas and beer inside the widget to jet out

from the hole. This agitation on the surrounding beer causes a chain

reaction of bubble formation throughout the beer. The result, when the can

is then poured out, is a surging mixture in the glass of very small gas

bubbles and liquid, just as is the case with certain types of draught beer such as draught stouts. In the case of these draught beers, which also contain before dispensing a

mixture of dissolved nitrogen and carbon dioxide, the agitation is caused by

forcing the beer under pressure through small holes in a restrictor in the

tap. The surging mixture gradually settles to produce a very creamy head.

The original widget was patented in the UK by Guinness.


The word "widget" as applied to this device is a trademark of the Guinness





Draught Guinness as it is known today was first produced in 1964. With

Guinness keen to produce Draught in package for consumers to drink at home,

Bottled Draught Guinness was formulated in 1978 and launched into the Irish

market in 1979. It was never actively marketed internationally as it

required an initiator which looked rather like a syringe to make it work.




The initial inventors of generating draught Guinness from cans or bottles by

means of a sudden gas discharge from an internal compartment when the can or

bottle is opened were Tony Carey and Sammy Hildebrand, brewers with Guinness

in Dublin, in 1968. This invention was patented by them in British Patent No

1266351, filed 1969-01-27, complete specification published 1972-03-08. Development work on a can system under Project ACORN focused on an arrangement whereby a false lid underneath the main lid formed the gas chamber. Technical difficulties led to a

decision to put the can route on hold and concentrate on bottles using

external initiators. Subsequently, Guinness allowed this patent to lapse and

it was not until Ernest Saunders centralised R & D in 1984 that work

re-started on this invention under the direction of Alan Forage.


The design of an internal compartment that could be readily inserted during

the canning process was devised by Alan Forage and William Byrne, and work

started on the widget during the period 1984/85. The plan was to introduce a

plastic capsule into the can, pressurise it during the filling process and

then allow it to release this pressure in a controlled manner when the can

was being opened. This would be sufficient to initiate the product and give

it the characteristic creamy head. However, it was pointed out by Tony Carey

that this resulted in beer being forced into the 'widget' during

pasteurisation with consequent very poor head quality. He suggested

overcoming this by rapidly inverting the can after the lid was seamed on.

This extra innovation was successful.


It is important that oxygen is eliminated from any process developed as this can cause flavour deterioration when present.


The first samples sent to Dublin were labelled "Project Dynamite", which

caused some delay before customs and excise would release the samples.

Because of this the name was changed to Oaktree. Another name that changed

was 'inserts' - the operators called them widgets almost immediately after

they arrived on site - a name that has now stuck with the industry.


The development of ideas continued. In fact over 100 alternatives were

considered. The blow moulded widget was to be pierced with a laser and a

blower was then necessary to blow away the plume created by the laser

burning through the polypropylene. This was abandoned and instead it was

decided to gas exchange air for nitrogen on the filler, and produce the

inserts with a hole in place using straight forward and cheaper injection

moulding techniques.


Commissioning began January 1988, with a national launch date of March 1989.


This first generation widget was a plastic disk held by friction in the

bottom of the can. This method worked fine if the beer was served cold; when

served warm the can would overflow when opened. The floating widget, which

was launched in 1997, does not have this problem.

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Taken on April 5, 2007