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What is Asbestos?

Asbestos is a term used to describe naturally occurring hydrated fibrous silicates of  which there are 6 common varieties.

Three were used commercially in quantity

These are:

• Amosite (brown asbestos) and
• Crocidolite (blue asbestos) have straight needle like fibres which naturally split along their long axis producing very fine fibres.
• Chrysotile (white asbestos) has mostly softer curlier fibres, which make them useful for weaving and has been used to make cloth for centuries.

 

Asbestos fibres can remain unchanged in the body for years.

The uses of Asbestos

The word asbestos was first used by the Romans in the first century AD, but by that stage the material had already been in use for about 2000 years. Archaeological evidence from Finland has shown that a type of asbestos was used to strengthen clay pots over 4000 years ago. In the first century AD the Roman Writer Plutarch, described a cloth woven from asbestos fibres that could be cleansed by immersion in fire, and when the Venetian Explorer Marco Polo returned from the East 1200 years later he too described a fire suit he had seen.

It was not until the late nineteenth Century that asbestos began to be used on a large scale in the manufacture of many different items.  From the 1880’s it was used increasingly in the textile industry to produce incombustible products, also gland packing and other linings for machinery. The different types of asbestos had some remarkable properties – with their resistance to heat, friction and chemical decomposition combined with their fibrous nature; and as the industrial age – particularly the development of the automobile – gathered momentum early this century, Asbestos began to be used in an increasing range of applications.

World War One saw asbestos being used as thermal insulation in Naval vessels and by the 1920’s the substance was firmly established as a vital ingredient in the manufacture of friction clutches and brake linings.

Coinciding with this increased use was the discovery of large reserves of white and blue asbestos in Russia, Canada and South Africa. Reserves of both were also found in Australia. 

Asbestos became popular as the reinforcing material in Cement products including wall claddings roofing materials, pipes and guttering and other building materials. At the same time it was used more and more in its raw state as an insulation material in buildings, around boilers and as a fire retardant around steel work and as noise insulation.

The post war period was the heyday of asbestos use in New Zealand and around the world. Each of the 3 main types of asbestos were sprayed and spread in what seemed to be an ever increasing range of applications throughout industry, as part of machinery components, and, to a lesser extent in homes. A United Kingdom report in the late 1970’s estimated that about 3000 manufactured products contained asbestos in one form or another. The same report said there were over 21000 people in the United Kingdom alone employed in the manufacturing of products which contained some degree of asbestos, and about the same number employed in processes which were subject to the asbestos regulations of the time.

Asbestos Use in New Zealand

Until just before the Second World War asbestos really only found its way into New Zealand in the form of manufactured items. Since that time, the only asbestos containing products that have been manufactured in any quantity in this country were asbestos cement building material, such as roofing and wall claddings, pipes and other molded products.

There have been 2 plants producing asbestos cement products. The first was established in 1938 at Penrose in Auckland, by the Australian Company James Hardie Ltd.  A second factory, operated by the local company Fletcher’s was established in the Christchurch suburb of Riccarton in 1943. Depending on the item being manufactured, they were made of a mixture  of  Portland cement, sand and usually between 5 and 15 percent of either chrysotile Amosite or crocidolite --- the asbestos acting as reinforcing because of it s fibrous nature and its high tensile strength. The types of asbestos used carried. The bulk was the white variety, chrysotile, which was cheaper and more easily worked.  Because the “best” blue crocidolite from South Africa was more expensive it tended to be used in only products requiring greater heat tolerance or strength (such as in pipes expected to contain higher pressures or temperatures). A lesser quality of crocidolite from the Wittenoom mine in Western Australia was also used to some extent. Amosite, or brown asbestos was imported from Rhodesia (now Zimbabwe).

The Auckland plant produced asbestos cement products  until 1987 although from 1983 asbestos had been phased out of sheet products and included only in pipes.  At peak production in the 1970’s the Penrose plant employed up to 600 employees at any one time.

The Christchurch plant, called Dunrock Industries, operated until 1974.  Estimates of the numbers employed over the life of the factory vary between 900 and 2000 – and are confused by the fact that large numbers of casual workers were employed.

Another major use of asbestos was as the raw material for insulation and acoustic products. This saw the various types of asbestos mixed with a binder and spayed around boilers, pipes, ducts and other places where insulation against heat and noise was needed.  From the 1950’s until the 1970’s thousands of tonnes of asbestos were applied in this way, most notably in the power stations built in the period, but also in railway workshops, shipbuilding and maintenance and other large scale industrial applications. Sprayed asbestos was also extensively used as a fire retardant for protecting structural steelwork.  Usually the insulation was applied by contractors who mixed asbestos from the bags or sacks it had been imported in, before spraying the mixture on to chicken wire reinforcing.

Other work places where asbestos was used included railway workshops, boiler rooms, and in fact most of the countries major industrial complexes where insulation against heat was required. Some of the industrial applications were less obvious.  For example, asbestos was commonly used in the brewing industry to filter beer from the 1920’s to the early 1970’s, and it was dropped into wine to act as finings and clarify the finished product. Another unusual use for blue asbestos was as a filtering component in gas masks of British Manufacture that were standard issue for troops and others from the First World War until after the Second World War.   An inner core of asbestos was surrounded by woolen wadding, and the item was standard issue to all New Zealand Troops in danger of gas attack.

Before the Second World War, asbestos was not imported in its raw state in sufficient quantity to appear in the import statistics.  With the beginning of local manufacturing and an increase in post war construction, more than 2000 tonnes were being imported annually by the late 1940’s. This continued though out the 1950’s with peaks of up to 5000 tonnes in some years. Usage increased dramatically during the 1960’s and until well into the 1970’s with the 5000 tonnes being a minimum amount being imported during those years, and the average being closer to 8000 tonnes. Imported asbestos peaked in 1975 at 12,500 tonnes though as recently as 1983, 3000 tonnes were imported.

Through out the 40 years asbestos was imported in large quantities, about two thirds of the amount imported was chrysotile from Canada, with the balance being made up of different types from Australia, South Africa or, to a lesser extent, the United States.

Asbestos was only ever mined in small quantities in New Zealand, as chrysotile from a single mine near Takaka from the early 1950’s until early 1960’s.  It was of low quality and had to be mixed with imported material. In the late 1960’s a sizable deposit was found near Dusky Sound, but for various reasons these were never exploited. Since 1984 the importing of Blue and Brown asbestos has been banned (in its raw state?).