Processing the raw material: from hides to leather

Vegetable tanning technology was not known in pre-Roman Britain, so the hides exported to Rome before the conquest (Strabo’s Geographica IV, 5) must have been preserved in some other way (above) to allow for transportation over long distances without decay. Despite the taxes incurred, it is possible that the export of partially processed hides may have continued throughout the Roman period, without tanneries ever having being established. However, the establishment of industrial-scale production facilities, both military and non-military, was not uncommon in Roman Britain. Continual exportation of untanned hides and importation of tanned hides throughout the 350 years of Roman occupation seems unlikely. The lack of excavated evidence for tanneries in Roman Britain is perplexing and suggests we may be failing to identify the relevant evidence.

Catterick, Binchester and Vindolanda have in the past been named as having yielded evidence for Roman period tanneries, although further analysis has indicated otherwise (Binchester International Field School interim report 2011-12, 8; Hooley 2002, 321-23; van Driel-Murray 2011, 69; Birley, R. 2009, 72-73). By considering the tanning process in discrete stages and identifying the infrastructure, supplies, structures and tools required, and the physical remains and by-products generated, van Driel-Murray has shown that the material evidence required to prove that tanning was taking place extends beyond some leather finds, one or two pits and insect evidence suggestive of a dirty environment. She asserts that the only confirmed example of a Roman tannery anywhere in the empire is at Pompeii, with a second possible tannery at Vitudurum, Switzerland (van Driel-Murray 2011, 71-80). Groenman van-Waateringe suggests two more: at the town of Saepinum, Italy, and at the site of the Gerasa hippodrome, Jordan (2009, 212). Evidence from Castleford suggests that leather might have been sourced over long distances: tanned goat hides arrived with the heads already removed, which might be interpreted as a move to minimise volume and weight, perhaps indicative of long-distance supply. In contrast, at Vindonissa, Switzerland, the heads were left attached, suggesting local supply (van Driel-Murray 1998, 329-31). The tanneries at Pompeii, Vitudurum, Saepinum and Gerasa certainly could not have fulfilled the Roman empire’s entire leather requirements. This leaves us with a considerable gap in our understanding of how the Roman imperial economy operated: we still have very little idea of where and how one of the empire’s most crucial resources was processed and supplied.

One of the Vindolanda Tablets is often cited in reference to the trade in hides in the Roman north:

“The hides which you write are at Cataractonium - write that they be given to me and the wagon about which you write. And write to me what is with that wagon. I would have already been to collect them except that I did not care to injure the animals while the roads are bad… Know that I have completed the 170 hides… A messmate of our friend Frontius has been here. He was wanting me to allocate (?) him hides and that being so, was ready to give cash. I told him I would give him the hides by 1 March. He decided that he would come on 13 January. He did not turn up nor did he take any

trouble to obtain them since he had hides. If he had given the cash, I would have given him them.” (Tab. Vindol. II, 343)

Octavius, probably a civilian entrepreneur, writes hastily to Candidus, perhaps an optio or centurion, at Vindolanda about the supply of goods including grain, sinew and hides (Bowman and Thomas 1994, 322; Evers 2011, 16-17).

The reference to ‘completing’ the 170 hides is often interpreted as meaning that the tanning process had been finished, and given as supporting evidence for the belief that there had been a tannery at Catterick. This theory is no longer supported for various reasons including the lack of excavated evidence (above), but the notion persists (e.g. Evers notes “what appears to be firm evidence of large-scale tanning activity” at Catterick (2011, 16)). Furthermore, the Latin word ‘exple’ that is translated as ‘completed’ refers to the “supplementation of the number of hides” rather than the finishing of any process such as tanning (Groenman-van Waateringe 2009, 213). Octavius simply indicates that he has the required number of hides to hand.

It is notable that there is a dearth of leather finds in Britain from the immediately post-Roman period (Cameron 2011, 86). Early historic leather finds are few. These include footwear (mostly fragmentary), leatherworking waste, a purse and a book satchel, and date to the mid/late sixth century at the earliest (Groenman-van Waateringe 1981; 2000, 128-33; 2001, 391; Crone and Campbell 2005; Alcock et al. 1989; DES 2013). Evidence for tanning is similarly scanty, and it may be that pseudo leather or rawhide was more commonly used (Cameron 2011, 91). Economic contraction in Britain in the fifth century saw the loss of a range of industries (bricks, tile, cement, wheel-thrown pottery) (Wilson 2006,232-34), and the lack of leather finds suggests that, even if tanneries were established in Roman Britain, tanning technology was not retained.

3.5.2 Arguments and evidence in favour of the establishment of tanneries in Roman Britain

The structures/facilities required for a tannery – pits, tanks/vats, drying frames, workshop space (van Driel-Murray 2011, 75) – are not particularly unusual or difficult to create, and on excavation such features might easily be misinterpreted as relating to some other occupation.

However, tanning is in itself a lengthy process: it might take two years, from flaying to finishing, to turn cattle hides to leather. Therefore tanning was “a capital intensive, large scale industry, requiring considerable long-term investment in raw materials, structure and space” (van Driel-Murray 2001c, 61). Indeed, far from being an artisan craft or cottage industry, van Driel-Murray suggests that our failure thus far to identify the archaeological evidence of tanning in Roman Britain might in fact stem from an underestimation of the scale of the industry (ibid.).

The Roman presence north of Hadrian’s Wall was intermittent, and the northern frontier supported significantly less Roman industry than central and southern England. This is aptly demonstrated by the relative scarcity of industrial sites such as pottery kilns. Nonetheless, significant industrial activity was undertaken on the northern frontiers: pottery kilns are known close to Hadrian’s Wall at Brampton and Scalesceugh (Bellhouse 1971) and further north at Newstead, Elginhaugh, Bearsden, Bar Hill and perhaps Croy Hill (Breeze 1986; Hunter and Carruthers 2012b, 48-49). However, the lengthiness of the tanning process may reduce the likelihood of tanneries having been established in northern Britain, where the Roman presence was discontinuous and less secure than further south: any partially tanned hides would be lost, should the military have cause to retreat south.

Tanning is a smelly and unpleasant industry, and we might argue that our failure to identify Roman tanneries stems from a focus on excavation of urban and military sites, when perhaps tanneries were placed in more remote locations. For example, the fifteenth century tannery at The Green, Northampton, was established in an all but abandoned part of town (Shaw 2011, 120)) however, in the medieval period, tanneries were more commonly located in urban areas (Burns 2012. Indeed, the tannery at Pompeii is located on the southern fringes of the city (van Driel-Murray 2011, 71) – on the periphery, perhaps, but still within the city limits. It is likely that tanneries in Roman Britain would also have been established in urban locations.

It seems highly improbable that all untanned hides were exported from Britain and tanned elsewhere, and tanned hides imported. This would have been neither time- nor cost-effective. Tanning requires little in the way of construction/installation and can be carried out almost anywhere provided that there is sufficient space and time. The tannery in Pompeii, which is the only example to convince the most eminent expert on the subject, Carol van Driel- Murray, was not even in a purpose-built structure. Rather, it was established in what had previously been a house. This serves only to highlight our failure thus far to recognise any ‘true’ tanneries set up from scratch. The physical clues of tanning – numerous pits/vats, covered sheds/frames, knives, paired post-holes indicative of drying racks etc (see van Driel- Murray’s comprehensive table (2011, 75, Table 1)) – might be fairly easily identifiable if viewed collectively, but could certainly be misinterpreted if only one or two elements were identified. The fact that a substantial structure or workshop is not necessarily required can only make identification of tanneries all the more problematic. It seems likely that tanning

was taking place in Roman Britain. We are simply not recognising its signatures in the

archaeological evidence.