![Cutty Sark stern](https://upload.wikimedia.org/wikipedia/commons/5/5a/Cutty_Sark_stern.jpg)
Muntz metal (also known as yellow metal) is an
alpha-beta brass alloy
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
composed of approximately 60%
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
, 40%
zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
and a trace of iron. It is named after
George Fredrick Muntz, a metal-roller of
Birmingham
Birmingham ( ) is a city and metropolitan borough in the metropolitan county of West Midlands in England. It is the second-largest city in the United Kingdom with a population of 1.145 million in the city proper, 2.92 million in the West ...
,
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
, who commercialised the alloy following his patent of 1832.
The alloy must be worked hot and is used today for corrosion-resistant machine parts. Alpha-beta (also called duplex) metals contain both the α and β phases. The α phase refers to a
crystal structure
In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystal, crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pat ...
that is
face-centered cubic
In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.
There are three main varieties of ...
, while the β phase is
body-centered cubic
In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.
There are three main varieties of ...
.
Its original application was as a replacement for
copper sheathing
Copper sheathing is the practice of protecting the under-water hull of a ship or boat from the corrosive effects of salt water and biofouling through the use of copper plates affixed to the outside of the hull. It was pioneered and developed by ...
on the bottom of boats, as it maintained the
anti-fouling
Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or small animals where it is not wanted on surfaces such as ship and submarine hulls, devices such as water inlets, pipework, grates, ponds, and rivers that ...
abilities of the pure copper at around two thirds of the price. It became the material of choice for this application and Muntz made his fortune. It was found that copper would gradually leach from the alloy in sea water, poisoning any organism that attempted to attach itself to a hull sheathed in the metal. Thus, it was also used to sheathe the piles of piers in tropical seas, as a protection against teredo
shipworm
The shipworms are marine bivalve molluscs in the family Teredinidae: a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into (and commonly eventually destroying) wood that is immersed in sea water, including ...
s, and in locomotive tubes. After successful experimentation with the sheathing Muntz also took out a patent for bolts of the same composition. These too proved a success as they not only were cheaper but also very strong and lasted longer. A notable use of Muntz metal was in the hull of the ''
Cutty Sark
''Cutty Sark'' is a British clipper ship. Built on the River Leven, Dumbarton, Scotland in 1869 for the Jock Willis Shipping Line, she was one of the last tea clippers to be built and one of the fastest, coming at the end of a long period of ...
''.
Company history
Muntz's new metal contained more copper, less zinc, and a bit of iron not present in a similar 56:44 alloy patented by William Collins in 1800. Production began on Water Street, Birmingham, but moved to Swansea in 1837. In 1842 he bought the French Walls Works in
Smethwick
Smethwick () is an industrial town in Sandwell, West Midlands, England. It lies west of Birmingham city centre. Historically it was in Staffordshire.
In 2019, the ward of Smethwick had an estimated population of 15,246, while the wider bu ...
, formerly the site of
James Watt Jr.'s ironworks. The site soon proved inadequate, and in 1850 a further were bought, on the other side of the
Birmingham, Wolverhampton & Stour Valley Railway. Eventually as the business outgrew Muntz’s own rolling mill in Birmingham, he joined in partnership with Pascoe Grenfell and sons who produced it at their Swansea mill as ‘Muntz’s Patent Metal Company’. They and other partners then fixed the prices of the alloy at £18 per ton lower than the market price for the equivalent copper product, serving to establish Muntz Metal as the sheathing of choice where transport costs still kept it as an efficient competitor. As an example of their success in entering the market, 50 ships were metalled with Muntz metal in 1837, over 100 in 1838, doubling in 1840 and doubling again by 1844.
With Muntz successfully supervising the manufacturing operations, by 1840 Muntz’s Patent Metal Company employed 30 men to smelt and roll the alloy and was producing 2,000 tons yearly. Three years later the Company had over 200 men producing 3-4000 tons yearly at £8 per ton profit. By then the Grenfells had left the partnership, for the agreement with Pascoe Grenfell & Sons had been terminated with some acrimony in 1842. When Muntz’s patent expired in 1846, they and others began making fastenings and sheathing to the Muntz patent at will.
Muntz died in 1857, to be succeeded by his eldest son, also called George Fredrick, who sold the business in 1864 to a joint stock company, Muntz's Metal Co. Ltd. In 1921 the company was bought by Elliott's Metal Company, which became part of ICI's Imperial Metals division (now
IMI plc
IMI plc (), formerly Imperial Metal Industries, is a British-based engineering company headquartered in Birmingham, England. It is listed on the London Stock Exchange and is a constituent of the FTSE 250 Index.
History
The company was founded b ...
) in 1928.
See also
*
Anti-fouling paint
Anti-fouling paint is a specialized category of coatings applied as the outer (outboard) layer to the hull of a ship or boat, to slow the growth of and facilitate detachment of subaquatic organisms that attach to the hull and can affect a vess ...
*
Biofouling
Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or small animals where it is not wanted on surfaces such as ship and submarine hulls, devices such as water inlets, pipework, grates, ponds, and rivers that ...
References
{{reflist
External links
National Pollutant Inventory - Copper and compounds fact sheet Patent, 1832
Patent, 1832
Patent, 1846
1852
1867
1874
1874
Copper alloys