Muntz metal is a form of alpha-beta brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...
with about 60% copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, 40% zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
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 West Midlands of England. It is the most populous British city outside the capital London, with a population of 1,036,900 , and lies at the heart of the West Midlands conurbation, the second most populous urban area in the United Kingdom with a...
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
who commercialised the alloy following his patent of 1832.
Known both as Muntz Metal and Yellow Metal, the alloy must be worked hot and is used today for corrosion resistant machine parts.
Its original application was as a replacement for copper sheathing
Copper sheathing was the practice of protecting the under-water hull of a ship or boat through the use of copper plates affixed to the outside of the hull. It was pioneered and developed by the Royal Navy during the 18th century.-Development:...
on the bottom of boats, as it maintained the anti-fouling 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. Later it was used to sheathe the piles of piers in tropical seas, as a protection against teredo shipworm
Shipworms are not worms at all, but rather a group of unusual saltwater clams with very small shells, notorious for boring into wooden structures that are immersed in sea water, such as piers, docks and wooden ships...
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
The Cutty Sark is a clipper ship. Built in 1869, she served as a merchant vessel , and then as a training ship until being put on public display in 1954...
Company historyMuntz'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 a town in the Metropolitan Borough of Sandwell, in the West Midlands of England. It is situated on the edge of the city of Birmingham, within the historic boundaries of Staffordshire, Worcestershire and Warwickshire....
, formerly the site of James Watt
James Watt, FRS, FRSE was a Scottish inventor and mechanical engineer whose improvements to the Newcomen steam engine were fundamental to the changes brought by the Industrial Revolution in both his native Great Britain and the rest of the world.While working as an instrument maker at the...
Jr's ironworks. The 4.5 acres (18,210.9 m²) site soon proved inadequate, and in 1850 a further 6.5 acres (26,304.6 m²) 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 were 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 it 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 100 Index.-History:...
) in 1928.
- National Pollutant Inventory - Copper and compounds fact sheet
- Improved metal sheathing, Patent, 1832
- Improved manufacture of bolts and fasteners, Patent, 1832
- Manufacture of sheathing metal, Patent, 1846
- On copper, 1852
- Sheathing, 1867
- Preservation of the bottom of iron ships, 1874
- Prices for anti-fouling compounds, 1874