Deconstruction: Blocklifting from the Blocklift
The largest soil block, after excavation
Feature 4, after consolidation with Paraloid B72 and Cyclododecane
Feature 4, covered in Clingfilm and enclosed by clay walls, with a small amount of polyurethane foam beginning to set. The foam support was built up in stages.
Feature 4 enclosed in rigid polyurethane support
As mentioned in the previous post, the only way to advance the study of this large blocklift was to take x-rays of the excavated ‘features’, in order to get a better idea of the condition of the archaeological metals, and to see if there were objects beneath the ones excavated. For this to happen, the five features had to be separated and lifted in miniature blocklifts.
As readers can see by the first photograph which shows the whole soil block after the completion of micro-excavation, separating features was a difficult task: whilst feature 1 was a discrete item, easily removed from the rest of the block, I had to make certain executive decisions about breaking up the rest of the block. Where possible, I tried to divide the features from each other using the cracks that were already present in the block, or by cutting over and under overlapping features. Inevitably, some damage did occur to the peripheries of features during the lifting process.
The process of blocklifting was remarkably easy: effectively, I blocklifted these features in the same way that they were lifted on site, except that as I was working in a laboratory, I had the opportunity to use conservation-grade materials in a much more controlled environment.
To begin with, I had to stabilise the artefacts in preparation for a process which would jar them quite a lot. I first consolidated the exposed artefacts using a removable adhesive called Paraloid B72, and then added a layer of melted wax, called Cyclododecane, to provide a more intimate support. Handily, this layer will eventually sublime by itself.
I then wrapped features in Clingfilm, to act as a barrier layer between the archaeology and the rigid material I would use hold the block together. For this, I selected polyurethane foam (readers may have come across this whilst completing DIY projects; it is often used as an insulating filler), as it has a very low density, and will not interfere with the attainment of an image of the mineralized iron plate. Polyurethane is prepared by mixing two liquid components together, and could be poured around the covered feature, reaching all nooks and crannies. Walls of plastic card and clay had been built around the feature to enclose the polyurethane.
Once the polyurethane had hardened, I began to pedestal the feature being lifted, before undercutting it. The separated feature could be turned over, and large amounts of extraneous burial deposit removed, which would have otherwise interfered with x-raying the metal artefacts.
I repeated this process until all the features were lifted, and prepared for X-radiography.
Caerleon Armour: Feature 5 and the Shoulder Plate
Feature 5, with interesting plates outlined
Back of shoulder plate
Back of shoulder plate, and depth of archaeological remains
This blog entry discusses the last area of the large soil block to be micro-excavated; feature ‘5’, located in the middle of the block. The position of the other ‘features’ (F1, F2, F3 and F4) in relation to this central one can be seen in the annotated photograph of feature 5, and plates with two identifiable edges have been outlined in various colours to guide the reader’s interpretation of this area. As with ‘feature 4’, feature 5 encompasses a large cluster of over-lapping iron plate, which have deteriorated significantly. In the centre is what looks like a shoulder plate (judging by the degree of curvature) lying on its side and seen in profile.
The third photograph show the back of the shoulder plate; you can clearly see how neat the corner of this plate is (despite the condition of the metal), and as with a plate in the previous entry, the corner of the plate looks rounded. Excitingly, a copper alloy rivets rests at the plate’s edge. Readers will have noticed that few copper artefacts or armour components have been recovered from the soil block assemblage overall- the armour (at least that which has been partially excavated) was efficiently stripped of copper fittings and pieces prior to deposition.
The fourth photograph illustrates the depth of the archaeology. Additionally, behind the main shoulder plate (outlined in yellow), is what I think is a second plate from the shoulder area of the cuirass (outlined in green). These plates were probably connected to each other in antiquity by the internal leather strapping, and it looks like their relationship has been preserved in the soil. Detecting the shorter edges of the second plate is difficult, as the heavily corroded plate has disappeared into a mass of blended of soil and iron corrosion products.
Beneath the first shoulder plate lies a distinctive plate with a good, clean edge (last photograph- as before, the shoulder plate is outlined using a dashed yellow line). This plate bears lumps of brighter orange corrosion products and given their relative size and positioning, I believe that these protuberances are all that remains of the interior fittings which would have held the leather attachments.
This entry marks the end of the micro-excavation stage of this conservation project: however, a huge amount of work remains to be completed before the contents of this soil block can be fully understood. As I have repeatedly mentioned, only x-rays will be able to provide us with a clearer idea of the exact condition of the iron artefacts, and of unseen objects beneath those excavated. The next stage will be to deconstruct the block into smaller blocks, of a size that will fit in the x-ray machine camber. The easiest way to complete this will be to essentially block lift the separate ‘features’ from the large soil block.
Micro-excavation of Caerleon Armour: Overlapping Plates and Curved Corners
Photograph of 'Feature 4'
Feature '4', boundaries outlined.
Profile of feature '4'
Plate labelled as '1' on overall photograph
This is a very short entry today, introducing feature ‘4’ of the block- a mass of overlapping plate. It has been difficult in this area to detect the edges of separate plates, and few diagnostic features have appeared. The first two photographs show the ‘feature’ overall (remember that the boundaries of this area are arbitrary constructions), and as in the previous post, I have included annotated and unannotated photographs.
The ‘profile’ of feature 4 can be made out in the third photograph. You can clearly see the burial deposit the lorica is resting on here- a real rubbish layer of soil, stones, bone and tile. This room was clearly neglected long before the dumping of the military items.
The fourth and fifth photographs show areas labelled as ‘1’ and ‘2’ on the overall annotated photograph. These plates are slightly more distinguishable than most in this cluster, and are recognizably plates of a lorica segmentata cuirass. These plates have straight edges, and in the case of plate ‘2’, two parallel edges, which can be measured (this plate is 7.5 cm in width) - these are important dimensions for curators, who can compare these measurements with those of lorica plates from other Roman sites, and work out where on the cuirass they might have come from.
Finally, one of the most interesting artefacts to come out of this feature is the plate shown in the sixth photograph, labelled as ‘3’ on the overall shot. It measures 7 cm in width and has a curved corner- this is great to find, as the corners of lorica plates were slightly rounded for comfort’s sake. Thus far, this is the only plate uncovered in this whole assemblage with this trait.
Continued Excavation of Roman Armour: Problems with Corrosion
Third area to be excavated in large soil block, without annotations.
Annotated photograph of 'Feature 3'.
Photograph of the edge of 'Feature 3'
Overlapping plates, with what is most likely remains of rivets used to attach leather straps to lorica plates.
This blog entry discusses the third section of the large soil block to be excavated: for ease of identification and documentation I have called this area ‘Feature 3’. This label will be important in the future, after I have deconstructed the block and need to be able to keep track of the position of groups of artefacts within this large assemblage. This instalment discusses a relatively small area of the block, with the main focus resting not so much on the lorica plates present, but on the corroded remains of fittings attached to them.
As here we are chiefly looking at vague shapes, I felt that it was important for this entry to include both annotated and un-annotated versions of photographs, so readers can come to conclusions without my interference. The first photograph is an image of this third part overall, and the second photograph includes arrows and boxes indicating particular areas of interest examined in this entry. The third photograph has been included to give the reader an idea of the depth of the archaeological artefacts, the thickness of the iron plate, and an impression of the poor condition of the remains.
In order to introduce the ‘fittings’, a short note on the corrosion processes that have taken place in these blocks is most definitely necessary. The more I excavate and study this block the more I realise that the different components of the lorica segmentata have corroded in dissimilar ways. The exposed plate has a firm, dark magnetite surface, on top of which are localised areas of powdery, orange corrosion. I believe this second, more disruptive type of corrosion product (an iron oxide), are the remains of iron rivets and fittings.
I think there are two reasons for the fittings to have corroded in a different way to the iron plate: firstly, as a result of being in contact with the leather strap which would have run vertically the length of the inside of the cuirass- the release of acetic acid by the leather could have jumpstarted corrosion. Secondly, the fittings could have corroded more quickly than iron plate, given the greater amount of working and energy required to create there more complicated shapes. The fourth photograph I think illustrates my theory quite clearly: here we are looking at rivets, belonging to two overlapping plates (which could well be in this position because they were neighbouring plates on the cuirass when in use, and at the time of deposition), that have corroded more drastically than the plate. I believe, given their shape and positioning these were rivets and washers holding the leather straps, and we are looking at the interior side of the plate.
Working on the above theory, the fifth photograph shows a detail photograph of the area enclosed within the dashed red box and marked with a ‘1’ on the main annotated overview. I believe this lumpy feature, clearly different in colour and texture to the plate underneath, is again the remains of rivets and washers holding the internal leather straps in place. You can see here how an iron component can corrode in such a way as to increase in physical size: the resulting ‘object’ is larger than the item really was in antiquity.
The sixth and seventh photographs show another area of plate with corroded fittings (and in the corner, a copper alloy rivet).Here we can see a rectangular feature (outlined in the seventh photograph), which I believe is essentially iron corrosion, holding the shape of a now non-existent leather strap.
An x-ray will hopefully provide more information about these ephemeral features, though detecting areas of corroded and degraded material (which will have a low density) on a background of denser archaeological artefacts and burial deposit, could be difficult.
Continued excavation and investigation of blocklifted lorica segmentata
Overall annotated photograph of second area of soil block to be micro-excavated. Red arrows point to corroded iron features, and a couple of fragments of copper alloy scale.
Gap between the two long plates- note the ragged and broken edges.
Fragment of plate with rolled edge.
Potential hinge (extremely corroded!)
Just a short blog entry today, describing the completed excavation of another area of the soil block, and some of the interesting features that have cropped up.
This section of the block is composed of what appears to be two flat lorica plates, one lying at a 45 degree angle to the other. Note the length of the straight edge of plate; I believe that this plate will be one of the large plates that came across the middle of the cuirass. I have included annotations indicating small areas of potential importance, such as the corroded remains of fittings (see red arrows), which stand proud to the surface of the plates. The gap between the plates, which shows how damaged and broken the edges of the lorica set really are, can be seen in the second picture.
I have found another fragment of plate with a rolled edge (see third photograph), though the roll itself is much narrower in comparison with that exposed within the girth hoop (refer to previous blog entry). The fragment itself is also a little too small to detect any curvature or to easily extrapolate a larger shape, but could this fragment be part of a plate (the breast or backplate) that would have been in contact with the wearer’s neck? All comments and opinions regarding this little hypothesis are welcome.
I have included a macro shot of a small cylindrical item: whilst this may be physically unimpressive, I believe that this could be the iron pin that would have been drawn through a lobate hinge, holding the shoulder plates together.
As mentioned above, obvious fittings that are immediately identifiable still haven’t been found, and careful excavation has only managed to produce vague shapes of what is essentially metal corrosion. I have included in the last photograph a view of an area of probable lorica attachments and fittings, though only a very good quality x-ray will be able to make any sense of these lumpy features.
As a last aside, I thought I should provide a brief explanation for the condition of the buried lorica segmentata. Readers may have noticed how exposed finds lack the thick crusts of rust and voluminous corrosion products typical of a lot of archaeological iron objects: this is most likely because the thin iron plates corroded extremely quickly, with the iron leeching into the soil. Whilst this does mean that I will not have to spend hours removing powdery iron corrosion in order to reach a more certain surface on the iron, it also indicates that the remaining ‘object’ is more of a pseudomorph lying on top of the soil: this is why the ‘plate’ most often does not respond to the pull of a magnet. This level of deterioration will have implications for the eventual conservation treatment of the armour, as I may be unable to extract the iron plates (which have very little physical integrity), from the soil.
Excavating a Girth Hoop
Girth hoop with copper alloy tie ring after excavation, and awaiting lifting.
Lorica plate in-situ, with rolled edge.
Back of girth hoop, after excavation.
Excavated depth of interior of girth hoop.
To the right is an image of the lorica segmentata girth hoop, complete with a copper alloy tie ring, after excavation in the conservation laboratory. The general shape of the hoop, which is lying on its side, can be discerned, and it is obvious that the plate is broken in several places. I had hoped to be able to see how the solid tie ring interacted with the girth hoop, but unfortunately too little of the iron plate remains in a stable enough state to remove enough of the obscuring soil currently supporting it. An x-ray of this area of the block will show the complete shape of the tie ring, and hopefully how it is attached to the plate.
To reiterate, I am excavating the artefacts in this soil block in the same way that archaeologists do in the field, and am coming across the same extraneous stones, silty-soil and common artefacts such as ceramic building material and animal bone contained within the burial deposit that are found on the average archaeological site. As the stones, tile, etc, do underlie so much of the fragile iron plate, I will not remove them at this stage, though I am aware they could be covering more artefacts.
Within the hoop further broken plates can be seen, most notably a flat plate with a rolled edge: this is one of the few plates that can at this early stage be attributed to a specific area of the cuirass; the only plates with rolled edges were the lowest girth hoop above the hip, and the breast and back plates. Given the flat nature of this plate, it is most likely the lowest girth hoop.
To give readers an idea of the depth of the archaeological remains in the soil block, I have included photographs of the back of the girth hoop, as well as a photograph showing the interior. Of interest in the third photograph is part of a plate held to the back of the girth hoop by corrosion and burial products, and how thin the lorica plate with a rolled edge is in the fourth.
Not all artefacts excavated in this area of the soil block can be as easily identified as the plate with the rolled edge; some of the iron has suffered greatly, and only vague shapes in the soil can be distinguished. Removing soil from the surfaces of these mineralized objects has been challenging, as I have to be careful not to take away any burial deposit that might contain corrosion that may be part or all that is left of the archaeological object.
I have not recovered as many fittings, such as buckles, rivets, washers and studs as those found on cuirasses from other Roman sites, and it will be these attachments, and their position on the body armour, that will be very important when trying to work out which plates were breastplates, backplates, shoulderguards, etc. As expected, I have not found many of the valuable copper alloy fittings which could have been removed for re-use during and after the occupation of the fortress by military forces, although I have found possible iron components, harder to spot given the corroded nature of the metal. For example, in the last photograph, the red arrows are pointing towards vague rectangular shapes slightly proud of what is an extremely fragmentary lorica plate; these might be the remains of fittings. Again, only high quality x-radiography will provide us with an image which might allow curators to make an identification of what these deteriorated artefacts are.
The hoop and other items will remain in place until the rest of the block has been excavated, when deconstruction will take place.
Block Blog: Primary Investigations
Annotated photograph of the first area of the block to be excavated in the archaeological conservation laboratory.
Flat iron plate with rivets.
Detail of cracked iron plate, typical of the lorica segmentata remains block-lifted last September.
Corroded copper sheet apparently wrapped around iron, here seen in broken fragments in-situ.
At this juncture in the investigation of this block-lift, I am making every effort to outline the relationships (if any) between artefacts. As can be see in the first photograph, plenty of small pieces of iron plate, often with no telling association with larger plates, emerge as soil is scraped away. Aside from photographing their position for future reference, and examining them for signs of the remains of fittings, impressions of textile or leather, there is not much that can be done with these anonymous fragments. Moreover, these fragments often overlie more interesting and coherent features, and so I am generally removing these: I will most likely x-ray these in large batches at a later date. As you can tell by the annotations, I’ve begun to get a good idea of the fragile nature of the fragmentary, corroded copper and iron artefacts mixed in the burial deposit, and have begun to grasp how difficult lifting the larger pieces of lorica will be.
So far I have had limited success at recovering any ‘true edges’ of the iron armour, as most of the vulnerable thin plate has been broken. Finding edges greatly improves our chances of identifying plates, and where two edges have been found, dimensions such as the width of the plate can give us an idea of which part of the lorica cuirass the plate comes from. It also helps us to make educated comparisons with examples of Roman armour found from other sites. For instance, the iron plate recovered in the second photograph has a width of 6.5 cm across, dimensions similar to those recorded for the armour fragments found amongst the Corbridge Hoard, and from the Austrian site, Carnuntum. It also has the very corroded remains of two copper alloy rivets, which improves our understanding of how the cuirass was constructed and held together.
As I work I am keeping the surface of the soil block wet, by spraying it with deionised water. This prevents the soil from drying out too much, separating, and breaking the iron remains as it falls into chunks. As most of the iron is in such a poor condition, consolidation with a removable acrylic adhesive, such as Paraloid B72 (ethyl methacrylate copolymer) is a must (which is why in some photographs the iron surface appears to have a dark sheen to it).
Whilst excavating an area of the block to the left of the photograph, I came across an exciting, (and sadly, very degraded) find: copper alloy wrapped around a thin iron plate. It can be seen in-situ in the photograph to the right, and after excavation in the photograph below. Sadly, as not much of the object has been recovered, a firm identification of this piece hasn’t been reached yet, though further excavation might yield more clues.
Readers may have noticed that I have begun to clean the outside of what is most likely a girth hoop. The exposed iron plate is 1mm in thickness, and the hoop is broken in several places, that I can see from the surface. When focusing on this feature, I will have to be careful to remove enough soil and other burial debris to reveal the curved plate’s shape, whilst maintaining the earthy support until I am ready to remove the that section of armour from the soil block. The next blog entry will focus on describing the results of excavations in this area, which includes a copper-alloy tie loop, still associated with the iron plate.
Discovered in Time, at Hay
Finally, only a year or so later, we launch fab new archaeology book Discovered in Time. We had a lovely event on the Hay Festival programme - pretty small in scale, but all the more enjoyable for it.
I knew the author, Mark Redknap, was a bit nervous and I felt suitably guilty. But I also knew he'd be great. He's articulate, knowledgeable, engaging and can throw in a soupcon of humour - ideal speaker material.
We'd pitched the event as a discussion on issues like who are we (museums) to decide what's 'treasure', or are we the natural authors of the national 'story', or de we hand over the 'voice' to communities (yes we do), and how do we relate to amateur archaeologists - all stuff I think is fascinating. Mark talked about those issues and illustrated them with some gems of stories related to various objects featured in the book. However the audience were also clearly drawn by the archaeology, and wanted some good old-fashioned archaeologists 'in the field' stories.
BBC journalist Sian Lloyd was our host for the event and she brought a fresh face and a sound journalistic approach, keeping the whole event expertly on track. The Q&A at the end included questions ranging from 'what was your Howard Carter moment?', which Mark gently explained can happen many times either with discovering a new find or with a new discovery about an old find, as we keep studying the collections and applying new technology, to the role of science in archaeology - see point about new technology. (And, is archaeology itself a science? Hmmm...).
I was really pleased that the audience comprised a healthy mixture of men and women, and all ages. What they had in common was that enduring fascination, which perhaps we all have, with the light objects that survive from antiquity can shed on our shared human past. And that, I hope, is just what our new book conveys.
Taking Stock of the Block
Cracks extending through the large block lift of Roman armour from Caerleon
Cyclododecane (the white, waxy substance in this photograph) holding fragile areas of armour togehter
Copper alloy scale armour- notice how the different pieces overlap and are linked together using copper wire through pierced holes
[image: Copper alloy stud, seen in-situ on surface of block. The white flakes are bits of plaster left from the lifting process]
Copper alloy stud, seen in-situ on surface of block. The white flakes are bits of plaster left from the lifting process
After documentation, the next step was to take stock of the overall condition of the block, and to make a preliminary inventory of the types of archaeological materials I could see.
As can be seen in the birds-eye-view photograph, there are some large cracks running across the block: these most likely occurred during lifting and transportation from the site to the museum. Unfortunately, these extend through some of the exposed armour, and areas of thin, mineralized iron plate have broken. This kind of damage, whilst regrettable, couldn’t have been avoided.
I wanted to keep the broken pieces in place for as long as possible, as the positioning of the remains is important to our interpretation of the events taking place in these two rooms of the warehouse. In order to ensure that fragments stayed together (at least for the interim) I used a wax-like substance called Cyclododecane, which I melted and brushed onto the artefacts. The Cyclododecane will eventually sublime altogether, and so I will not have to remove it later.
In addition to the iron plates, there are also a range of other interesting artefacts visible on the surface of the block. There appears to be a scattering of copper alloy scale armour (see photograph for an example), which would also have been worn by a soldier.
At the edge of the block is a large copper alloy stud, its use in antiquity currently unknown: it is not an artefact which has been associated with lorica segmentata. As the photograph shows, the copper has corroded considerably and is very thin.
Scattered amongst these exciting finds are the usual types of artefacts found during archaeological excavations: pieces of red ceramic tile, fragments of pottery, bits of animal bone, and crumbly lumps of white plaster (from the building itself).
Excavating the block will be both time consuming and challenging: I have selected a number of small tools to use. I am unable to place a microscope over the block, and so will be using an optimizer (a visor with magnification lenses) instead- I do not want to miss any small artefacts or details during the excavation.
Conservation of Roman Armour- Opening the Block
The block in the conservation lab. The white and black pole lying across the block is a metre in length- just to remind you how large the block really is!
[image: The Clingfilm layer which had been protected the iron underneath from the Plaster of Paris bandages. The sides of the block had been carefully re-bandaged to ensure that the soil block held together. ]
The Clingfilm layer which had been protected the iron underneath from the Plaster of Paris bandages. The sides of the block had been carefully re-bandaged to ensure that the soil block held together.
[image: The block revealed! As the block is so large, in order to take a 'bird's-eye-view' photograph from above, climbing to the top of a step-ladder was required. ]
The block revealed! As the block is so large, in order to take a 'bird's-eye-view' photograph from above, climbing to the top of a step-ladder was required.
[image: String was used to section the block and make drawing easier. ]
String was used to section the block and make drawing easier.
After wheeling the large block into the archaeological conservation laboratory, I began the task of removing the plaster bandages covering the top of the block.
This proved a simple and satisfying job- the bandages were easily torn off in layers, revealing the Clingfilm barrier underneath. In order to reinforce the sides of the block, yet more bandages were wetted and wrapped around it.
The next step in opening up the block was to peel back the Clingfilm. This had to be done very carefully, as I didn't want dust from the plaster covering the archaeological artefacts beneath. Pegs and bulldog clips were very useful in holding back the plastic layers neatly.
After much anticipation, the armour was revealed. As I had not been present during removal of the armour from the fort, this was the first time I was able to see the lorica, and I was very impressed by the corroded remains.
As I excavate the armour contained within this soil block, I have to document every individual feature, and the physical relationships between all the artefacts. This provides invaluable information for the archaeologists working on the project, who want to tell the story of Isca.
This documentation process involves taking many photographs and making copious notes day by day; before I even begin to excavate the block using small hand tools, I drew a plan of the whole block, at a 1:2 scale. It was easiest to do this by laying string across the top of the block, and drawing it in sections.
After all this preparation, I cannot wait to get started excavating the soil overlying the armour and other artefacts- though this will take a very long time.