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David Moore, retired tropical forester (and father of pipemaker Hamish), served for many years in the UK Colonial Forest Service and as a consultant to the Food and Agriculture Organisation of the UN. At last month's Collogue in Birnam he gave a talk on timbers for bagpipes, their characteristics, their availability and their future. We reproduce here the paper on which his talk was based.

THE CHARACTERISTICS of suitable timbers for the manufacture of bagpipes can conveniently be divided firstly into those physical features which arise from the nature and arrangement of the cell structure of the timbers and secondly from the presence of other materials which, for the moment, we shall refer to as MISCELLANEOUS DEPOSITS (see Appendix II).

There are four main PHYSICAL properties to consider, bearing in mind that none is absolute in itself and that one characteristic may modify one or more of the others.

The first of the PHYSICAL properties is that of density. This can be loosely defined as the weight of a given volume of a substance in relation to the weight of the same volume of water. Thus, suppose that 1 cubic foot of a particular timber weighs 68 1/2 lbs and a cubic foot of water weight 62 1/2 lbs, then by dividing 68 1/2 by 62 l/2 we obtain a density of

1.09 for the timber.

Density is of major importance since it affects the resonance of a timber, and the densities of cocus wood, partridge wood, ebony and African blackwood all fall within the range of 1.1 to 1.2 when the MOISTURE CONTENT of the timber is about 12 per cent. I will refer to moisture content later. In comparison with these densities, those of the indigenous timbers used before cocus wood etc became available varied between 0.75 and

0.85. It is clear that the resonance of pipes made from the indigenous species must have been inferior in tone to those of today, since the density of blackwood, for example, is half as much again as that of the indigenous species.

 

A second physical property affecting musical quality is the STRUCTURE of the timber. For clarity and richness of tones, a timber must have a FINE, as opposed to a COARSE texture.

A third physical factor affecting musical quality is SHRINKAGE. As we know, all timber shrinks as it dries. Suppose we represent a log thus:

 

As it dries out, the outer layers shrink on a core which remains wet and therefore the same size. Something must give, so the out layer splits over the wetter core. It is of great advantage, therefore, to cut up the log as after felling as possible into the sizes required, and in the case of blackwood this is now generally done. The ends are coated with wax to retard end-drying and related cracking.

There is a great deal of mythology attached to timber seasoning, but in point of fact, effective seasoning is no more than controlled drying to a point where the remaining moisture is in equilibrium with the average relative humidity of the environment in which it is to be used.

Considering shrinkage in more detail, we suppose that the log shown overleaf is being

cut in the saw to provide as many chanter blanks as possible, the remainder going into shorter components such as drone sections.

The square ABCD in the section on the left represents a chanter blank and with respect to the growth rings, the face AB is a tangential face while the face BC is a radial face.

Shrinkage on the tangential face can be up to twice that on the radial face, so that when the chanter blank is properly seasoned it is no longer a square in section but oblong as shown above.

 

When a chanter is turned from a properly seasoned blank, it will remain relatively stable, but if the timber is wet when turned, not only will the outer surface of the chanter become in time slightly oval, but, more importantly, the bore of the chanter will also change from perfectly round to slightly oval as the timber

dries out. The deformity is exaggerated in the figure for the purpose of illustration above, but in reality we know that a deformation of only a fraction of a millimetre will affect the acoustical properties of the instrument.

Now we shall consider a fourth factor physical factor, namely DIMENSIONAL STABILITY. Let us assume that we have a chanter made from fully seasoned timber. Over its useful lifetime the chanter will be exposed to widely different moisture conditions, depending on how wet a blower the player is and the humidity of the environments in which the instrument is played. Minute dimensional changes occur in response to such variable conditions. Any wood, therefore, in which tangential and radial shrinkages or expansion are approximately similar will retain the circularity of the bore to a greater extent than those in which radial and tangential shrinkage differ widely. The presence or absence of natural waterproofing agents in the wood will greatly increase dimensional stability and of course the example of such a wood par excellence is the African blackwood tree.

Earlier I said that timber characteristics can be divided into PHYSICAL and MISCELLANEOUS DEPOSITS. WATER is one of the miscellaneous components of all timbers, and in some species such as balsa, can weigh in freshly felled logs more than ten times as much as the dry wood matter itself. In others, such as blackwood, it constitutes only about 25-30 per cent. For many purposes, it is necessary to accurately know how much moisture is contained in wood - in the kiln drying of woods, for instance, or in the manufacture of plywoods. This measure is known as the MOISTURE CONTENT and is expressed as a percentage of the weight of the dry wood matter present.

In practice, the moisture content is frequently determined electrically by means of a resistance measurement, but for accurate determinations a sample of timber is weight then oven dried, with weighings repeated at intervals of about a half hour, until two successive identical weights are obtained, thus indicating that all of the moisture has been driven out of the wood.

Investigations over many years show that timber settles down to a moisture content in equilibrium with the average environment at about 12 per cent moisture content. It will be lower in wood stored in a centrally- heated house and higher in wood kept in a damp cellar. In practice, pipe makers keep a supply of timber blanks in their shops for a selected length of time, at the end of which it is assumed that the timber is suitable for working.

The second of the MISCELLANEOUS DEPOSITS are those laid down in trees as the trunk and branches pass through the transition phase between the actively growing cambium, just below the bark, and the physiologically inert but mechanically supportive

 

tissue of the heartwood. These deposits in this transition area, which later become heartwood, include silica, mineral oils, resins and gums. Some of these agents provide waterproofing and improve the dimensional stability, as in blackwood. In the case of ebony, the nature of the deposits is different. During the transition phase of tree growth, ebony undergoes a process analogous to, but not identical with, fossilisation.

Having discussed the characteristics of timber for pipe making, we now turn our attention to the subject of AVAILABILITY, which I'll deal with in three chronological but overlapping periods: INDIGENOUS, TRANSITION and EXOTIC. During the INDIGENOUS PERIOD, spanning the 14th to the late 17th centuries, bagpipes were made from local timbers only. We can only surmise at the species then used, but it seems probable that makers used boxwood, hornbeam, laburnum, holly, yew and various fruitwoods.

The TRANSITION period began in the 17th century and lasted, surprisingly, until the early years of the 20th century. During the 16th century, the Spanish, English and French were engaged in bloody rivalry in the West Indies, and by the first half of the 17th century the English were colonising Barbados, St Kitts, Trinidad, Jamaica and other places. It seems reasonable to suppose that for many years afterwards, cargoes shipped to England from these colonies consisted of valuable commodities such as tobacco and spices. At a later time, perhaps during the late 17th century, additional resources such as fine timbers and logwood for dyes began to be exported. In the case of woods for pipe making, these colonial timbers would have become available by the end of the 17th century and would have included cocus wood from Jamaica, lignum vitae from various places in the West Indies and, later, rosewood from Belize, followed by partridge wood from Venezuela.

Parallel to, but later than developments in the West Indies, the fledgling East India Company was laying the foundations for what would eventually become the “jewel in the crown” of the then British Empire - the colonial annexation of India. From the early 1800s onward, gradually increasing shipments of ebony and rosewood from India, together with exotic timbers from the West Indies, progressively displaced the indigenous timbers previously used to make bagpipes. Details of wood purchases by the Glens of Edinburgh in the mid-18th century can be found in Hugh Cheape's excellent paper The Making of Bagpipes in Scotland. (1) The same paper also records the fact that as late as the early 1900s, a pipe maker in Dundee was still making pipes from laburnum and that Robert Reid, whose shop I remember in George Street in Glasgow, remarked of them, “They are all right for lighting the fire with!” Certainly I know of one laburnum set being played in the late 1920s to early 1930s in the Boys Brigade band in which I was a piper.

I consider the time from the early years of this century to the present to be the EXOTIC period since nearly all Highland pipes made in this time have been from imported timbers. Early this century, as cocus wood became more scarce (and remember that there was great competition for supplies from such manufacturers as Boosey & Hawkes for other woodwind instruments), ample supplies of ebony met the demands.

 

(1) The Making of Bagpipes in Scotland by Hugh Cheape MA, BA,FSA (Scot), pages 596-615, From the Stone Age to the Forty-Five, published by John Donald, Edinburgh, 1983

 

Concurrently, and particularly after the First World War ended and the UK took over German East Africa (Tanzania), the region was opened up to increased commerce.

Blackwood came on to the market in steadily increasing quantities and, because of its superior characteristics, has in time displaced ebony. I would imagine that from about 1945 all reputable pipe makers have used blackwood exclusively.

It is worth discussing this species in more detail. The distribution runs from the old Anglo-Egyptian Sudan, through Uganda and Kenya to Tanzania, Malawi, Mozambique and the two Rhodesias. It grows sparsely throughout the savanna type of forests called miombo forests which occur at elevations of less than 5,000ft in rainfall zones of 35in to 45in per year and with dry seasons of seven to eight months.

Soils are generally poor and the total of all tree crowns in the forest cover less than 50 per cent of the ground. Botanically, the blackwood belongs to that wonderful genus Dalbergia, which with over 120 species includes such important “musical” timbers as kingwood, Brazilian tulipwood and rosewood, cocobolo, Honduras rosewood and Indian rosewood. The tree is often a scruffy, multi-stemmed runt of 15 to 25ft, but occasionally as high as 50ft.

The species has been heavily exploited commercially but, to put this into perspective, I understand that bagpipe manufacture accounts for about 2 per cent of the volume exported. Much of the miombo forest is being destroyed by shifting cultivation and by excessive burning to stimulate new wet season grasslands for grazing. Regeneration is therefore at a standstill and, since it can take up to 80 years for a sapling to reach commercial size, the outlook for long-term supply is poor indeed. Actual quantities reaching the United Kingdom have improved in past years but this is because Tanzania is no longer restricted to one government agency. Private companies are now exporting, but this means that the existing crop will be cut out all the sooner.

The question arises: from what will bagpipes be made when traditional materials become so scarce that timber is priced out of the market? Various types of plastic have been available for many years, but their tonal qualities are generally unacceptable. In the case of maple (Acer Sp.) impregnated with epoxy resin, the density is in the region of 1.18 and the tone is excellent but, particularly in the case of Highland pipers, there are objections to the cream colour of the wood.

Hamish Moore has produced quite a number of sets of small pipes from an industrial material called Permali which is used mainly as a high-voltage insulating material. Permali consists of laminates of beech (Fagus sp.) impregnated with high-density resin which is then heat-treated and produces a material of a pleasing reddish-brown colour which, when turned on the lathe, appears to have a natural and interesting grain. The material is virtually impervious to moisture, and therefore to dimensional change. Its density is 1.28 and the tonal quality excellent.

This is certainly the best of the substitute materials by far and, for those areas in which extremes of relative humidity occur, it is ideally suited, especially for spall pipes, in the manufacture of which no technical difficulties are encountered, although machining problems may arise in the manufacture of Highland pipes.

 

This paper, The Characteristics and Availability of Suitable Timber Species in relation to the Past, Present and Future Manufacture of Several Forms of Scottish Bagpipes, is based on a talk given to the Piobaireachd Society Conference at Bridge of Earn in 1991, and later at North Hero, Vermont.