Pontypool japan tray, detail, Cardiff Museum

Pontypool japan is a name given to the process of

japanning Japanning is a type of finish that originated as a European imitation of East Asian lacquerwork. It was first used on furniture, but was later much used on small items in metal. The word originated in the 17th century. American work, with ...

with the use of an oil

varnish Varnish is a clear transparent hard protective coating or film. It is not a stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, and is sold commercially in variou ...

and heat which is credited to Thomas Allgood of

Pontypool Pontypool ( cy, Pont-y-pŵl ) is a town and the administrative centre of the county borough of Torfaen, within the historic boundaries of Monmouthshire in South Wales. It has a population of 28,970. Location It is situated on the Afon Lwyd r ...

. In the late 17th century, during his search for a

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...

-resistant coating for

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

, he developed a recipe that included asphaltum,

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

and burnt umber. Once applied to metal and heated the coating turned black and was extremely tough and durable.

is in a steep valley in

South Wales South Wales ( cy, De Cymru) is a loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the historic counties of Glamorgan and Monmouthshire, south Wales extends westwards ...

, surrounded by

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...

and iron working. The iron used was produced by the furnaces of Blaenavon to the north, and most of the " Pontypool ware" was actually produced in nearby Usk or Newport, at the southern end of the valley.

Background

In the late 17th century, there was a developing trade in metal goods made of thin iron sheet, spurred by development of the

rolling mill In metalworking, rolling is a metal forming process in which metal stock is passed through one or more pairs of rolls to reduce the thickness, to make the thickness uniform, and/or to impart a desired mechanical property. The concept is simil ...

Rustproofing Rustproofing is the prevention or delay of rusting of iron and steel objects, or the permanent protection against corrosion. Typically, the protection is achieved by a process of surface finishing or treatment. Depending on mechanical wear or e ...

this iron was important. Tin plating had been developed in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

, and British manufacturers needed to compete. While it was the growth of the iron foundries and tin plating that gave birth to

on metal, tin plated iron was not the only metal used. There are examples of

brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...

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 pink ...

and

bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloids suc ...

used as substrates. In

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

copper was the metal primarily used. Because it had to be hammered into shape rather than rolled and stamped the surface was uneven. This did not provide the best surface for japanning thus it has a greater tendency to flake off than the smoother English tinware. When the French made tinware it was often trimmed with bronze. The use of metal allowed a variety of forms that were required to withstand heat and water. Coffee pots, tea sets, candle sticks and other household items could all be japanned and decorated in the popular fashion. These japanned metal objects are very stable so a great many still survive. Many pieces survive today with little rust. In most cases it is easy to ascertain the underlying metal because it can be seen in losses or scratches. If the japanning is intact, a

magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nicke ...

can be used to identify iron. Most iron trays show some rust on the back where only a single coating was applied. Even the tin plated iron objects show rust in some areas. It is worth remembering the unavailability of effective paint, at this time. The surface finishes that did exist either had poor adhesion to their substrate, or required either a

porous Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

or an

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

substrate to bond to. Today's resin-based paints for metals had not been invented.

Recipes

Similar recipes or "secret varnishes" were also used in

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 We ...

. In his book on Pontypool japan (W. D. John, 1953), published one of the recipes the workmen had handed down through generations: * 448 pounds of raw

* 22 pounds of lump

umber Umber is a natural brown earth pigment that contains iron oxide and manganese oxide. In its natural form, it is called raw umber. When calcined, the color becomes warmer and it becomes known as burnt umber. Its name derives from ''terra d'omb ...

* 20 pounds of flake

litharge Litharge (from Greek lithargyros, lithos (stone) + argyros (silver) ''λιθάργυρος'') is one of the natural mineral forms of lead(II) oxide, PbO. Litharge is a secondary mineral which forms from the oxidation of galena ores. It forms as co ...

* 100 pounds of asphaltum * 5 pounds of

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

resinate * 406 pounds of

white spirit White spirit (AU, UK & Ireland)Primarily in the United Kingdom and Australia. In New Zealand "white spirit" can also refer to Coleman fuel (white gas). or mineral spirits (US, Canada), also known as mineral turpentine (AU/NZ), turpentine substitu ...

turpentine Turpentine (which is also called spirit of turpentine, oil of turpentine, terebenthene, terebinthine and (colloquially) turps) is a fluid obtained by the distillation of resin harvested from living trees, mainly pines. Mainly used as a special ...

The linseed oil was heated together with the umber and the asphaltum while the litharge and cobalt were added slowly. According to the recipe, the varnish was ready when a drop of varnish dripped onto cold glass remained in a ball. After cooling, the turpentine was added. There was also a pale clear version which omitted the asphaltum and the cobalt. In modern tests, this varnish worked equally well on papier mâché and metal plates. Three coats produced a durable glossy black finish. This recipe is similar to one for gold size published by both (Robert Dossie, 1764) and (Stalker and Parker, 1688). In that version, linseed oil is boiled together with gum animi, asphaltum,

and umber in approximately the same proportions as the Pontypool recipe. (Watin, 1755) also describes the use of asphaltum as an addition to the well-known spirit varnishes of the day. It appears that the secret recipe for Pontypool japan had been in existence for some time before its use for japanning metal.

References

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Background

Recipes

See also

References

Further reading