Even within the leather making sector, the preference for hide purchases based on area instead of weight have been the subject of both debate and investigation. However, neither measurement by weight nor area provides a truly accurate yardstick for predicting either yields or costings. So why weight?

Practicalities of hide collection

Where the meat-processing sector is rationalised, then hides, although a waste within a well-managed food processing organisation, can be readily categorised. In this situation, an area assessment of each hide could be made, although they do not lie flat, before proceeding with preservation or passing rapidly into leather manufacture. However, in practice it is easier to weigh a flayed hide, than to open out, feed onto a conveyor for area measurement on an expensive machine and then unload. The measurement option is thus slower, more expensive and requires a greater working area.

In the global hide market, the choice between area and weight determinations is not realistic. At the smaller end of the chain, animal slaughter is local, with hide collection through well-established networks of dealers and traders. Area measurement is too difficult to manage through each transaction, and weight is the long established norm.

However, the information provided by this measurement is far from perfect from the purchaser’s points of view. The goods may be categorised, and the weight of each hide identified. But what does this really mean?

Variations in moisture content

Normally, when a commodity is purchased by weight the moisture content becomes a prime factor in assessing true value. Measurement is easy, with composite samples available for analysis. However, this does not occur in the sale of hides and skins.

Although the moisture content may be relatively uniform when the hide is removed from the animal, this changes. Hides are often washed to reduce the skin temperature or to remove blood, and the hide holds much of this water. However, if the hides are preserved by salting, then this is accompanied by a dewatering. Often the brine runs away from the hide, but if the piles are high, then hides at the bottom of the pile will retain more moisture. 

Examples can even be found where high moisture retention is encouraged, with a maximising of preserved weight. On the other hand, if air movement is high in curing or storage, then extra dewatering can take place. Taking matters a stage further, in hot climates hides are often dried out after salting to reduce the weight and thus the costs of transport, and to provide extra security against putrefaction. In other words the moisture content changes: the weight at slaughter cannot be verified and practices within preservation throw up different values.

Effects of hide and leather characteristics on yields

Yield is a factor that is not fully addressed by either hide weight or area measurement. For example, if an ox hide is compared to a cowhide of the same weight, then the potential yields are very different. The ox hide is comparatively thicker in the parts carrying most muscle and requiring most protection, whereas the cowhide is thinner and more extended in the belly areas.

This means that the potential area of a grain leather is less from an ox hide than a cowhide of the same weight. If the thickness of the final upper leathers were based on the lower substance potential of the cowhide, then the area obtained from the ox hide would be less, but the substance and area of the (lower value) flesh split would be greater. 

However, when hides are sorted, the selection takes both quality and potential substance into account. Ox hides go for higher substance leathers, requiring a greater selling price because of the extra weight of hide per unit of area, whereas cowhides are designated for lower substance leathers of greater area, being theoretically of lesser unit value.

The hide area also affects yield. In practice, splitting and shaving causes damage to the shanks and other peripheral areas, with a greater percentage loss with pieces of smaller area. Similarly, pleating associated with vacuum drying or toggling is proportionately greater with smaller pieces. This is trimmed away to minimise subsequent machine damage, and as part of acceptable customer presentation.

The yield also varies according to customer needs and the processing used by the tanners. As a general rule, softer leathers, because of the relaxation within the leather structure, do not produce such high area yields as an extended, firmer leather.

Hidden factors

Other factors that are not first apparent can also affect the prediction of values based on either hide weight or area assessment. This includes the effects of infestations, poor animal husbandry, pre-slaughter practices and low level putrefaction, as these affect the grain quality. These potential losses in terms of area and value cannot be fully revealed until the hair is removed. 

Moreover, defects due to poor flaying practices, such as flay cuts or gouges, might not be apparent initially, but limits splitting and shaving to low substances. This is to avoid these defects remaining in the flesh side of the grain leather and to provide acceptable cutting coefficients in clicking. Nevertheless, these practices are coupled with a loss in substance potential, hence value. Over and above these issues, the reduced value of the flesh splits need taking into account. They now carry the flesh cuts that have become holes, and gouges identified as areas of low substance.

In addition, fringe grain damage may not be apparent until the wet blue stage, and even not revealed until the dry pre-finished state. In the worst situations, the leathers might be fully finished before the damage is clear, with subsequent rejection or downgrading.

Clearly, the arena of hide classification and quantification, area yield, substance potential and ultimate value are largely determined before commencing leather manufacture, with little chance of verification. However, where linkages have been formed between meat processors, hide merchants and wet blue units, rationalisation is possible. This is particularly so where close attention is given to the value-added chain with integrated responsibilities and incentives.

In this event matters can be better controlled and the hide is no longer ‘unknown’. With wet blue purchases the grain can be seen, quality reasonably assessed, potential substance evaluated and measurement by area readily managed for the first time.

Security from known values

Where the value of raw hides is traditionally based on weight, with purchases from known and trusted sources, the experienced tanner has long converted weight and category into yield and sales value for a known type of leather. Moreover, understanding the market and predicting shifts rather than just following the classic value adding exercise has often generated good profits. 

On the other hand, many tanneries have vanished through poor judgement and bad purchases rather than lack of in-house technique or management abilities. Perhaps the stability offered by the more transparent wet blue state is of longer term benefit to both leather manufacturers and their customers.

Tanners: commodity or niche manufacturers?

The value of raw hides is subject to the pressures of supply and demand. In this event, when demand exceeds supply, the rising values are often coupled with a marked decrease in quality. Nevertheless, much of the value of a raw hide lies in the fact that it offers considerable flexibility to the tanner which is essential when meeting specific customer demands.
However, as the leather industry has evolved, the development of specific leather properties has largely moved from pre-tannage and tannage to dyeing, retanning, softening and mechanical and drying areas. Where chrome tannage prevails, specialised wet blue properties are no longer required. The wet blue simply needs to be versatile and consistent.

1. Tanners processing from the raw to finished state have therefore acquired two conflicting in-house objectives:
   The demands of commodity manufacture. Wet blue is available as a commodity in the external market. Success is therefore based on uniformity of supply and flexibility of use, coupled with high volume throughput to minimise manufacturing costs. Furthermore, the value of a manufactured commodity can only progress from this stage if linked within a genuine adding value structure. This means meat processing/wet blue linkages with associated advantages and incentives.
2. The demands of niche manufacture. Typically, the niche market means highly focused production with fine attention to detail. This is especially so when serving the fashion sector, where textures and colour requirements are subject to rapid change, and production runs are relatively small. In this event margins can be high, but these are only effective if the potential of the raw material is as required and fully utilised. Variable raw hides do not fit easily into this equation; the need is for a closely defined wet blue.

Neither the philosophies of manufacture, nor the optimum plant size, suits these two different objectives and it is very difficult to see how they can fit together in a single production plant. Perhaps this is another reason for a lack of profitability and closures in the raw to finished sector of the tanning industry in the past, especially when supplying the footwear sector. 

CREDIT: ROSESHUTTERSTOCK25

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