How Black Antique Iron is Made and Why Kirkpatrick is Special
The Kirkpatrick Iron Foundry
The history, why their products are special and how they make them
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Cast in Style has a long history with Kirkpatrick and we have, in fact, made speciality products for them ourselves in the past. This allows us to offer you their outstanding products, safe in the knowledge we are one of their preferred suppliers.
Why are Black Malleable iron products special?
Before we go into detail about Kirkpatrick it is important to understand why their products are special. All Kirkpatrick products are 100% British Made and take over six weeks to complete. Kirkpatrick make their products from malleable iron, not cast iron. This is an important difference and should be understood. Cast iron is a superb medium for items such as brackets, knobs and other non moving parts. It is very strong under compression, such as when used as a bracket, but brittle under tension. Malleable iron is much stronger and less brittle under tension and this makes it excellent for thin items and moving parts such as hinges and gate latches.
How is Malleable Iron made?
Malleable iron is basically cast iron which has had an extra special heat process added to it during it's production. This 'annealing' process gives the iron malleability (hence the name malleable iron). This makes the iron much stronger and gives it a slight elastic property which, unlike cast iron, stops it from being brittle. Stopping cast iron from being brittle has been a special technique used by Kirkpatrick for 140 years. Because the iron is now malleable, component moving parts are now able to be hand riveted together giving a very much stronger joint which will never break. This cannot be done with cast iron because it is brittle and therefore runs the risk of breaking. Many cheap imported products which look the same as Kirkpatrick products are make from cast iron and the component parts are held together using cheap spring washers which will usually break at some point, we do not sell these cheaper products. Each and every product from Kirkpatrick is individually hand riveted (where required), this ensures outstanding quality which is unsurpassed anywhere.
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100% British Made
Overall you can be confident when you buy a Kirkpatrick product you are guaranteed to be purchasing a 100% British made product, made in the original foundry in Walsall, West Midlands, which has been hand finished in a process that takes over six weeks to complete and possessing a quality that is unsurpassable and will last you a lifetime. We are so confident in Kirkpatrick products we offer a returns no quibble guarantee.
William Kirkpatrick, Esq., J. P. (1817-1887). Founder, in the year 1855, of the business in Walsall, that was carried on for many years in his name and under his direction. His son, Vincent Kirkpatrick, succeeded his father and presided over the incorporation of the business as a Limited Company in 1901. Upon incorporation, many loyal and long serving employees were given a shareholding. This started a tradition which continues to this day. Many of the descendents of those first shareholders still retain their interest in the Company and the Kirkpatrick family still also retain a shareholding.
The Original Kirkpatrick Logo
The origin of "I mak siccar” forms a direct link with one of the most decisive events in Scotland’s history. The defeat of Wallace by Edward 1 at Falkirk in 1298 was reputed to be due to the defection of the forces of John Comyn, Earl of Badenoch, to the English. After the capture and execution of Wallace in 1304, Comyn had ambitions of becoming King of Scotland himself. It was at the Monastery in Dumfries that Robert the Bruce, a strong supporter of Wallace, and Comyn came face to face. They quarrelled. Comyn was stabbed by Bruce. Rushing out to his escorts Bruce told them, "I doubt I have slain Comyn.” Roger Kirkpatrick, saying "I mak siccar” (I’ll make certain) ran into the building and finding Comyn wounded but alive, stabbed him to the heart. Subsequently, Robert the Bruce was crowned King of Scotland in 1306.
How are Kirkpatrick Products Made?
The first process is is to prepare the moulds into which the iron will be poured. This is a skilled job and requires a lot of practice. This job is usually done by the same person who pours the iron. He will want his mould to be perfect as he will be responsible for the final cast to come out of it. A special black sand is used which is mixed with a small amount of oil as a bonding agent. A metal box called a matchbox is filled with sand and the pattern is pressed into this to form one half of the mould. Its top surface is then dusted with powder to stop it adhering to the other half of the mould. The other side is then prepared and the two halves put together. A hole is made for the iron it be poured into and smaller holes for the gases to escape through. The pattern used for the moulds are original 140 year old patterns used when the company was originally formed back in 1855.
The casting process starts off with the raw grey iron. It is comprised of about 95% iron and 5% graphite and silicone The silicone helps carbon to be release quickly from the iron when it melts. Carbon is an unwanted component embedded in the raw iron and will be released as it melts. The graphite acts as a lubricant to assist in pouring the iron. It is broken down into a granular form which makes it easier for the furnace to smelt.
The grey iron above is added to the furnace to melt. Kirkpatrick use an induction furnace which is electric. Magnetic coils are energised and the energy passes into the iron through an electrical process called induction. The energy is so great it heats the iron to about 1200 °C at which point it melts.
Unwanted products form on the top of the liquid iron as it melts. These need to be removed before it can be poured (see left photo). The unwanted waste is then removed from the furnace and disposed of. Most of it is comprised of carbon and sulphur (see right photo).
Collecting the Iron
When the iron is ready the casters prepare to fill their pots with iron. The pots they carry have been pre heated in a small oven as pouring iron directly into a cold pot will make it explode with the differing temperature (see left photo). The furnace is then tipped up and the iron flows from it to be caught by the casters in their pots (see right photo).
Each take it in turns to fill their pots. The iron is very heavy and so every care is taken at this stage from accidentally dropping it (see left photo). As the last of the men fill their pots others are already pouring the iron into the mould they make earlier (see right photo).
Pouring the Iron
The moulds are all laid out on the floor in even rows. Each one has a heavy weight placed on the top of it. This is the plate with the cross in the centre of it in the picture. The weight is very important as the liquid iron could explode as it makes contact with the cool sand. The weights prevent the iron from exploding apart the sand moulds by keeping them intact.
Pouring the iron is heavy work and several pots are filled and poured before all the moulds are full (see left photo). Care is taken with every pour and a slow but constant flow is required to get the iron to fill the inside on the mould evenly (see right photo)
The iron reacts as it comes in contact with the cooler sand and sparks are generated as it is quickly made to cool (see left photo). Everybody works together as efficiently as possible when the iron is being poured. Time is of the essence as the iron will be rapidly cooling into a solid state (see right photo).
The heavy weights which prevented the iron from exploding earlier are removed from the tops of the moulds (see left photo). The moulds are now left to cool. The iron will be cold enough to remove in only a few minutes, but will be still too hot to touch (see right photo).
Removing the Casting
The moulds are picked up and taken to the sand pit at the end of the row where the sand is knocked off to reveal the casting (see left photo). Each casting has a waste run of iron connected to it. This is the path the iron took in the mould to flow around it. This needs to be removed by hand from every casting (see right photo).
The scrap runoffs are collected and weighted ready to be re-melted down in the next batch of iron. Nothing is wasted (see left photo). At this stage the various castings are still cast iron and are in a rough form with sharper edges. These need to be removed (see right photo).
The barrelling machine is used to smooth off the sharp edges. The barreller is filled with hundreds of the castings and a quantity of abrasive rocks. It then revolves like a washing machine. The components inside rub and knock against each other smoothing their surfaces.
The annealing process is the special part of the sequence. This turns the cast iron onto malleable iron. This is done using and annealing oven. Round pots are filled to the brim with the cast iron products and are subjected to a heat treatment process known as annealing. In this process castings are heated to around 1000 °C for up to 4 days whilst in contact with haematite ore. The ore acts as an oxidising agent which removes carbon from the casting. It is the presence of carbon in cast iron which causes its brittleness and removing some makes the casting stronger or more malleable.
The pots from the annealing oven are stored ready to be reused again (see left photo). The annealing process makes the iron bend and it comes out of the annealing oven miss-shaped. Each piece then has to be individually hammered back into shape to make it straight again (see right photo).
Grinding and Felting
The straightened castings, which are now malleable iron, are stored ready for the next stage (see left photo). Each casting still has rough edges and unwanted seams from the mould it came from. They are individually painstakingly removed by hand on grinding and fettling machines (see right photo).
The cleaned up castings are taken to the large workshop where they will be filed and assembled (see left photo). Again each casting needs to be painstakingly hand filled in the more intricate places to remove unwanted sharp edges and rough surfaces (see right photo).
For items such as window catches and latches as well as hinges a rivet needs to be fitted. The rivets are all hammered into place by hand to ensure a perfect seal is made. Riveting can only be done on malleable iron as cast iron will crack. Cheaper copies are made from cast iron and a rivet fitted in this way cannot be done. Instead they will fit a cheap spring washer to hold the parts together. This will nearly always break over time. Kirkpatrick's rivet will never break or come out.
All the castings are still bare metal at this stage and will rust if not painted. Two special paint processes are used. Dipping and powder coating. Cheaper imports will not be dipped and this is a crucial stage to ensure the casting will not rust. Dipping is a process where by the castings are hung onto a hanger and lowered into a very liquid paint. This ensures every surface of the casting is coated in a layer of paint to stop it from rusting. As some of the castings have been riveted together this is especially important to make sure the paint soaks into every joint. This is not done with cheaper copy's and so rusting at these points is inevitable.
The dipped castings are left out to dry ready for powder coating (see left photo). Powder coating is a modern process which gives a superb finish to the iron and a long lasting durability. A special dry powder is sprayed onto the castings in an enclosed chamber. The powder coating for a black colour looks brown but this will change in the next stage (see right photo).
The powder coated casting are attached to hooks ready travel along the conveyer to the oven (see left photo). The castings travel along the conveyor to where they enter the oven, where they are baked for a few minutes. This hardens the powder coating and also makes them change colour to black. The powder coating hardens in the oven and becomes a very tough hard wearing surface. It also makes to castings look beautiful and last a lifetime (see right photo).
After they come out of the oven they are given a light spray of light oil to help prevent them from rusting further while they are in storage (see left photo). The now finished products are boxed, packaged and stored ready for dispatch (see right photo).
The whole process above takes about 6 weeks for each individual product. As you can see every stage is done by skilled craftsman by hand and this gives Kirkpatrick products an unsurpassable quality, look and feel. Owning a Kirkpatrick product ensures you are receiving the very best you can possible buy for your home. The original heritage is still maintained and you will be purchasing a distinctive product which will last you a lifetime.