Spile
Encyclopedia
A spile is a small wood
en peg used to control the flow of air into, and carbon dioxide
out of, a cask
of ale
.
Cask ale
is served without externally-supplied carbon dioxide or nitrogen. The idea that it is served "flat" with no bubbles at all, though, is a misconception; properly conditioned cask ale contains bubbles of carbon dioxide generated by the natural action of the yeast
living in the beer while it is transported and stored. In fact, the yeast will actually produce more carbon dioxide than is required, and it is for this reason that the cask is vented through the spile hole in the shive
.
Two kinds of spile are available. Initially, "soft" or porous spiles are used, made of open-grained softwood
, bamboo
, or harder wood with cuts in. These allow the excess gas to escape. Once the cellarman judges this process to be complete, a hard spile is inserted which does not allow any more gas out of the cask. These are made of harder wood (usually still technically "softwood", but denser and more solid than soft spiles). Plastic pegs intended for sealing shives are occasionally used as hard spiles.
During service, the spile must be removed to allow air in to replace the beer drawn off. Once the spile is reinserted enough gas will come out of solution to replace what was lost, but the amount of carbon dioxide available in the system - free or dissolved - is limited, so it is important that the spile is kept in as much as possible. This is one of several reasons for real ale's short shelf-life once a cask is opened - if too much carbon dioxide is lost, the beer will be flat. Typically, the beer will be good only for two to four days; this short life is why it is important that a pub serving real ale have sufficient turnover for casks to be emptied while still at their best.
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
en peg used to control the flow of air into, and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
out of, a cask
CASK
Peripheral plasma membrane protein CASK is a protein that in humans is encoded by the CASK gene. This gene is also known by several other names: CMG 2 , calcium/calmodulin-dependent serine protein kinase 3 and membrane-associated guanylate kinase 2.-Genomics:This gene is located on the short arm of...
of ale
Ale
Ale is a type of beer brewed from malted barley using a warm fermentation with a strain of brewers' yeast. The yeast will ferment the beer quickly, giving it a sweet, full bodied and fruity taste...
.
Cask ale
Cask ale
Cask ale or cask-conditioned beer is the term for unfiltered and unpasteurised beer which is conditioned and served from a cask without additional nitrogen or carbon dioxide pressure...
is served without externally-supplied carbon dioxide or nitrogen. The idea that it is served "flat" with no bubbles at all, though, is a misconception; properly conditioned cask ale contains bubbles of carbon dioxide generated by the natural action of the yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
living in the beer while it is transported and stored. In fact, the yeast will actually produce more carbon dioxide than is required, and it is for this reason that the cask is vented through the spile hole in the shive
Shive
A shive is a wooden or plastic fitting used in ale casks. It is found on the curved side of the cask, arranged so that when the cask is on its side and the keystone is at the lowest part of the rim, the shive will be the highest point of the cask....
.
Two kinds of spile are available. Initially, "soft" or porous spiles are used, made of open-grained softwood
Softwood
The term softwood is used to describe wood from trees that are known as gymnosperms.Conifers are an example. It may also be used to describe trees, which tend to be evergreen, notable exceptions being bald cypress and the larches....
, bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....
, or harder wood with cuts in. These allow the excess gas to escape. Once the cellarman judges this process to be complete, a hard spile is inserted which does not allow any more gas out of the cask. These are made of harder wood (usually still technically "softwood", but denser and more solid than soft spiles). Plastic pegs intended for sealing shives are occasionally used as hard spiles.
During service, the spile must be removed to allow air in to replace the beer drawn off. Once the spile is reinserted enough gas will come out of solution to replace what was lost, but the amount of carbon dioxide available in the system - free or dissolved - is limited, so it is important that the spile is kept in as much as possible. This is one of several reasons for real ale's short shelf-life once a cask is opened - if too much carbon dioxide is lost, the beer will be flat. Typically, the beer will be good only for two to four days; this short life is why it is important that a pub serving real ale have sufficient turnover for casks to be emptied while still at their best.
Other uses
Like many such older terms, the word spile has other local meanings. For example:- The iron spigot driven into a sugar maple to produce maple syrupMaple syrupMaple syrup is a syrup usually made from the xylem sap of sugar maple, red maple, or black maple trees, although it can also be made from other maple species such as the bigleaf maple. In cold climates, these trees store starch in their trunks and roots before the winter; the starch is then...
.
- At Indian Harbor in Nova Scotia, the shores on which fish processing "stores" were located were called spiles.
- Spile is also a term used in boatbuilding to describe the means/actions which a builder uses to determine the shape of any curved piece needing to be fitted to a curved surface.