Pitch (resin)
Pitch is a name for any of a number of viscoelastic, solid polymers. Pitch can be made from petroleum products or plants. Petroleum-derived pitch is also called bitumen or asphalt. Pitch produced from plants is also known as resin. Some products made from plant resin are also known as rosin.
Pitch was traditionally used to help caulk the seams of wooden sailing vessels (see shipbuilding). Pitch was also used to waterproof wooden containers, and is sometimes still used in the making of torches. Petroleum-derived pitch is black in colour, hence the adjectival phrase, "pitch-black".
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Viscoelastic properties [edit]
Tar pitch is a viscoelastic polymer. This means that even though it seems to be solid at room temperature and can be shattered with a hard impact, it is actually fluid and will flow over time, but extremely slowly. The pitch drop experiment taking place at University of Queensland is a long-term experiment which measures the flow of a piece of pitch over many years. For the experiment, pitch was put in a glass funnel and allowed to slowly drip out. Since the pitch was allowed to start dripping in 1930, only eight drops have fallen. It was calculated in the 1980s that the pitch in the experiment has a viscosity approximately 230 billion (2.3×1011) times that of water.[1]
Production [edit]
The heating (dry distilling) of wood causes tar and pitch to drip away from the wood and leave behind charcoal. Birchbark is used to make Birch-tar, a particularly fine tar. The terms tar and pitch are often used interchangeably. However, pitch is considered more solid while tar is more liquid. Traditionally, pitch that was used for waterproofing buckets, barrels and small boats was drawn from pine. It is used to make Cutler's resin.
"Smolny" [edit]
In the early days of St. Petersburg, the area then at the edge of the city where pitch ("smola" in Russian) was processed for use in shipbuilding and maintenance got the name "smolny" - the place of pitch. From this was derived the name of two buildings later erected at this location, prominent in Russian history - the Smolny Convent and the Smolny Institute.
