Falun red or Falu red ( ; , ) is a red iron oxide pigment obtained as a byproduct of the Falun copper mine. It is traditionally used as a pigment in applied to exterior wood surfaces in

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

, and

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

. ''Falu Rödfärg'' is a protected trademark, which may only be used for products containing red pigment sourced from the Falun Mine. ''Rödfärg'' ( Swedish), ''rödmylla'' (

Finland Swedish Finland Swedish or Fenno-Swedish (; ) is a Variety (linguistics), variety of the Swedish language and a closely related group of Swedish dialects spoken in Finland by the Swedish-speaking population of Finland, Swedish-speaking population, common ...

) or ''punamulta'' ( Finnish) can refer to any flour paint containing either natural

red ochre Ochre ( ; , ), iron ochre, or ocher in American English, is a natural clay earth pigment, a mixture of ferric oxide and varying amounts of clay and sand. It ranges in colour from yellow to deep orange or brown. It is also the name of the col ...

or industrial iron oxide pigments.

History

After centuries of copper mining in

Falun Falun () is a city and the seat of Falun Municipality in Dalarna County, Sweden, with 37,291 inhabitants in 2010. It is also the capital of Dalarna County. Falun forms, together with Borlänge, a metropolitan area with just over 100,000 inhabit ...

, large piles of residual materials were deposited above ground near the mines. By the 16th century, mineralization of the mine's tailings and

slag The general term slag may be a by-product or co-product of smelting (pyrometallurgical) ores and recycled metals depending on the type of material being produced. Slag is mainly a mixture of metal oxides and silicon dioxide. Broadly, it can be c ...

, added by smelters, began to produce a red-coloured sludge rich in

copper Copper is a chemical element; it has symbol Cu (from Latin ) 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 pinkish-orang ...

limonite Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as , although this is not entirely accurate as the ratio of oxide to hydroxide can vary qu ...

silicic acid In chemistry, a silicic acid () is any chemical compound containing the element silicon attached to oxide () and hydroxyl () groups, with the general formula or, equivalently, . Orthosilicic acid is a representative example. Silicic acids are ra ...

, and

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It 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 periodic tabl ...

. When this sludge was heated for several hours and mixed with linseed oil and rye flour, it was found to create an excellent anti-weathering paint. In the 17th century, Falun red began to be applied to wooden buildings to mimic the red-brick façades commonly used by the upper classes. In Sweden's urban areas, wooden buildings were often painted with Falun red until the early 19th century, when authorities started opposing its use.

Resurgence

Falun red saw a resurgence in popularity in the Swedish countryside during the 19th century, when poorer

farmer A farmer is a person engaged in agriculture, raising living organisms for food or raw materials. The term usually applies to people who do some combination of raising field crops, orchards, vineyards, poultry, or other livestock. A farmer ...

s and

crofter A croft is a traditional Scottish term for a fenced or enclosed area of land, usually small and arable, and usually, but not always, with a crofter's dwelling thereon. A crofter is one who has tenure and use of the land, typically as a ten ...

s began to paint their houses. Falun red is still widely used in the countryside. The Finnish expression "" ('a red cottage and a potato patch'), referring to idyllic home and life, is a direct allusion to a country house painted in Falun red.

Composition of flour paint

The paint consists of water,

rye Rye (''Secale cereale'') is a grass grown extensively as a grain, a cover crop and a forage crop. It is grown principally in an area from Eastern and Northern Europe into Russia. It is much more tolerant of cold weather and poor soil than o ...

flour Flour is a powder made by Mill (grinding), grinding raw grains, List of root vegetables, roots, beans, Nut (fruit), nuts, or seeds. Flours are used to make many different foods. Cereal flour, particularly wheat flour, is the main ingredie ...

linseed oil Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colorless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...

, silicates,

iron oxides An iron oxide is a chemical compound composed of iron and oxygen. Several iron oxides are recognized. Often they are nonstoichiometric, non-stoichiometric. Ferric oxyhydroxides are a related class of compounds, perhaps the best known of which is ...

, copper compounds, and zinc. As Falun red ages the binder deteriorates, leaving the color granules loose, but restoration is easy since simply brushing the surface is sufficient before repainting. The actual color may be different depending on the degree to which the oxide is burnt, ranging from almost black to a bright, light red. Different tones of red have been popular at different times.

References

External links

*
Mould resistance tests in Sweden (Falu on page 5, in Swedish)
{{shades of red Dalarna Shades of brown Shades of red Iron oxide pigments Culture of Sweden Culture of Finland Culture of Norway Recycled building materials Paints Swedish inventions