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A Closer Look: Saw-Toothed Enameled Brooch

In this post we will be examining a single enameled brooch (SF 0532) excavated from Cardiff Castle. This is one of a handful of enameled brooches of the 51 recovered from the excavations. We will take an in-depth look of this object to provide a sense of the amount of work that can go into a conservation related examination.

Slide1

The object is a copper alloy T-shaped brooch that was covered in thick deposits of soil and copper corrosion. Most of the deposits were removed through mechanical and chemical cleaning to reveal 3 fragments: 2 pins fragments and the brooch body. The pin fragments were small and highly corroded.

The technology of the body consists of a bow that partially wraps around the wings (arms) at the head. The wings are a single hollow tube with a notch cut out on the reverse for the central pin. Cleaning of the wings revealed iron corrosion products within the pin notch and on both ends of the wings. This indicates an iron axis bar to which the copper alloy pin was connected. The bow has a broad flat raised center with 4 diamond-shaped lozenges used to hold the enamel. The edges of the bow are serrated to form a saw-tooth effect.  The lower bow is slightly tapered ending in the rounded foot with a dark blue glass bead embedded in the center. The reverse of the bow is generally flat except for an incomplete pin catch-plate which extends from the lower bow reverse.

Slide2

Humans are wonderful at pattern recognition. This can be useful but also misleading as sometimes we see something that may not actually exist. The four lozenges on the bow are similar in size, spacing and orientation. Below the fourth lozenges towards the foot is an area of deeper green of a similar size, spacing and orientation to the existing lozenges. Could this be a fifth lozenge? It could, however, the texture is similar to the copper corrosion products on the surface of the brooch. More investigation is required to determine if the fifth lozenge exists.

Slide3

An x-ray was taken to further elucidate the mystery. The x-ray was developed, scanned and digitally enhanced. The brighter areas represent denser areas on the brooch. We can see that the wing tube is, indeed, hollow. We can see the stub of the pin at the head of the brooch. It is slightly off-centered indicating that the brooch was at a slightly oblique angle during the x-raying process. We can see a more clearly defined section of the saw tooth edge on the bow. We can see the pin catch-plate on the lower bow (brighter area near the bottom) and we can see the semi-rounded notch that holds the glass bead at the foot. We can also see four lozenges used to hold the enameling along the bow. The fourth lozenge is slightly obscured by the catch-plate and any evidence of a fifth lozenge is completely obscured.

Slide4

So, does any enameling remain and what colour would it have been? Microscopic examination reveals the possibility of a pale green enamel remaining in at least two of the four lozenges. McIntosh (2007) writes that typical first century AD Romano-British enameled brooches consist of red enameling with blue and yellow used less frequently. The colour palette was expanded in the second century to include green, orange, black and white. Blue was the most dominate colour and would often be used in conjunction with red. By the third and fourth centuries blue and white were commonly used.

Now, the colour of the remaining enamel could, in fact, be a pale green just as it looks in the photographs. However, I know through my experience with Egyptian faience glazes that copper-based blue glaze colour can be reduced to a pale green if exposed to water which can leach elements (e.g. sodium) from these materials. The colour of the enamel remains mysterious… or pale green just as we see it.

Slide5

While under the microscope I decided to further examine the potential fifth lozenge site. What I saw were two overlapping possibilities in its placement. Knowing human nature, these two overlapping potential placements may just be evidence that, as a human, I am forcing the existence of the fifth lozenge whose existence seems much clearer when viewed from further away but upon closer examination becomes mottled. I am not so sure this lozenge actually exists.

Slide6

What I do know is that there is clearly a blue glass bead on the foot of the brooch. Maybe further examination of this glass bead can help solve the mystery of the enamel colour in the bow lozenges. Relying on the previous experience with Egyptian faience I was expecting the colourant of this bead to be cobalt. A quick qualitative analysis using portable x-ray fluorescence (pXRF) will clearly identify the cobalt. Now, in full disclosure, the pXRF analysis was covering the whole foot of the brooch, not just the bead. But even so, the cobalt present in the bead should still be obvious. Only, it wasn’t.

Slide7

I compared two pXRF spectra: one from the beaded foot (green spectrum and hard to see behind the red spectrum) and one from the back of the bow with no enameling (red spectrum). The spectra comparison from the pXRF analysis showed the same elements although there was disparity in the photon counts (the heights of the peaks) that could easily be explained by air attenuation, or the blocking of photons due to air molecules between the brooch foot and the pXRF. In other words, the back of the brooch bow made greater contact between the brooch and the pXRF than the brooch foot. Regardless, there was no cobalt. Use of the pXRF was extremely easy but to use additional methods, such as the scanning electron microscope, would require research into enameling so that I knew what to expect.

McIntosh (2007) and work conducted by Bateson and Hedges (1975) on the analysis of Romano-British enameled brooches indicated that copper can be used as a colourant for reds, blues and greens, and although previous research (Harden (1956) and Forbes (1957)) said that cobalt wasn’t used in Roman glass, Bateson and Hedges (1975) identified it in nearly all the blue enamel they analyzed. I needed to take a closer look at the blue glass bead using the scanning electron microscope (SEM).

Slide8

The SEM I had access to has three detectors: secondary electron imagery (SE), energy dispersive spectroscopy (EDS) and Backscattered Electron imagery (BSE). SE imagery produces the 3D images we are familiar with concerning SEM. This includes those 3D images of bees and fly eyes and other similar subjects that can easily be found in the internet. This would not be helpful to me.  The other two methods would be helpful. BSE produces a 2D black and white image (slide 8). It will show contrast in heavier and lighter elements and can show the difference in density of materials imaged with higher density showing up as more white and lower density as more black. This method would help in determining areas of glass from areas of copper alloy and/or copper corrosion. In other words, this would help me in finding suitable areas to analyze using EDS. EDS will show me all the elements that are present in the sample site being analyzed and, in this way, is very similar to pXRF analysis. SEM-EDS, however, allows me to analyze a much smaller area than pXRF.

Slide9

The four lozenges and the existing blue bead were imaged using BSE. The bead appears dark in comparison to the surrounding material. This is to be expected as glass is less dense than copper alloy. Additionally we see some higher density material on the bead surface. This is most likely deposited copper alloy corrosion material from the body of the brooch. BSE images of the four lozenges alternate between bright and dark. The darker images (with brighter areas along the edge) could represent an existing glaze similar to how the glass bead showed up darker in the previous image. The other two lozenges show a brighter area surrounded by slightly less dense material. This probably represent deteriorated glass where elements have been leached from the glass leaving an artificially elevated amount of lead than what is usually encountered with enamel. Lead is commonly found in all Roman enamel as its characteristic affect melting, colouring and its adherence to the metal substrate (the brooch). The brighter areas in these images can be a result of nearly all of the glass having dissolved and been carried away by moisture in the burial surroundings, lead being particularly stubborn to dissolution.

Slide10

EDS provides us with a spectra showing the elemental peaks. Many of the peaks are labelled but great care should be taken as automatic peak identification is can commonly mislabel peaks. Slide 10 shows spectra 1-2 (glass bead), 4-5 (brooch body) corresponding to the spectra in slide 9. There is no indication of cobalt in this blue glass bead. This indicates that copper is responsible for the blue colour. This also indicates that cobalt cannot be used in a qualitative mode to determine the colour of an enamel simply because it is not present.

Slide11

This slide shows a BSE image similar to slide 9 where five locations have been analyzed using EDS. The EDS result in the brighter glaze areas of the first and third lozenge (from the head) does reveal higher levels of lead suggesting, as previously hypothesized, that the enamel has deteriorated leaving an artificially high level of lead.

So, we have an enameled brooch with four definite lozenges and the possibility of a fifth. The blue colour of the glass bead is due to copper. Its darker colour may be due to the thickness of the bead. The alternating bright and dark lozenges in the BSE images could be evidence of alternating colours (and an alternating propensity to dissolution) or a differentiation in deposition moisture levels/flow across a small area that resulted in differentiated dissolution of the enamels.

Copper, used for green, blue and red, is the only colourant identified and is consistent in all the enamels. Unfortunately it is also present in the copper alloy brooch and the copper alloy corrosion overlying everything. In this case our tenacity has resulted in little demystifying of the enameled brooch. It has shown, however, the amount of work that can go into an object. There can be a lot of chasing down leads that lead to nowhere, determine what something can’t be, and/or determine what it actually is.

Slide12

This final picture shows the brooch with two potential enamel colour patterns. I have also included the fifth lozenge which may not have existed. The first image shows the brooch as we see it. We have a pale green enamel in the lozenges with a blue bead at the foot. The second image shows the pattern with blue inlays similar to the foot bead colour. The colour could have been red but my argument against this is that we have red existing on another brooch (to be discussed in another post) and it seems that it would be just as resilient on this brooch. A similar argument can be made against the lozenge enamels being blue. The deep blue (where is the cobalt?) of the glass foot bead doesn’t appear to have diminished so why would the potential blue enamel along the bow? The only answer is that the blue bead was protected from moisture and certainly water flow for over 2000 years while the bow enamel wasn’t. Possible but unlikely. Ultimately the colour determination remains unconfirmed.

We will examine another enameled brooch in the next post. The thumbnails below can be clicked upon to bring up a larger higher resolution image. Be safe!!!

References Cited:

Bateson, J. D. and Hedges, R.E.M (1975) The Scientific Analysis of a Group of Roman-Age Enamelled Brooches. Archaeometry 17 (2) pp. 177-190

Forbes, R. J. (1957) Glass. Studies in Ancient Technology 5, pp. 110-231

Harden, D. B. (1956) Glass and Glazes. A History of Technology, ed. Singer et al., Oxford, pp. 311-346

McIntosh F. (2009) A Study into Romano-British Enamelling with a Particular Focus on Brooches. The School of Historical Studies postgraduate Forum E-Journal Edition 7, Newcastle University, pp. 1-18

 

 

 

 

 

Cardiff Castle: Recently Excavated Roman Brooches

Introduction

This post will examine a sampling of 7 brooches recently excavated from Cardiff Castle. A total of 51 brooches and fragments were brought into the laboratory to be cleaned and conserved. Many of these are fragmented remains and/or highly corroded. The 7 selected brooches are nearly complete and represent a cross-section of the general Cardiff Castle brooch assemblage. The names of the brooches are provided by the archaeologists prior to cleaning and all brooches are presented at the same scale. The photographs are presented as thumbnails at the bottom of the page. Clicking on the thumbnail will present the reader with a higher resolution image.

All of the objects were covered in loose surface soil deposits from the burial matrix and required mechanical cleaning combined with alcohol impregnated cotton wool swabbing. The work was conducted using a microscope. Additional work, if any, will be provided within the description of the brooch.

The Brooches

SF 0072 Hinged Bow Brooch

The brooch is hinged with a pin inserted into a hollow tube. The pin was most likely composed of a copper alloy as there are no iron corrosion products around the hinge. A hatched line runs along a slight ridge down the bow to the foot of the brooch. The catch-plate appears to be openwork based on the remnants. The brooch has a patinated surface with minor pitting.  It is structurally intact and stable. It is in good condition.

Slide1

SF 0132 Trumpet Brooch

The brooch has the typical trumpet head oval in shape. Behind the head is a single vertical lug for the spring. The spring is missing. Above the head is a plate with a round ring attached. The bow exhibits a central knop with petals above and below. The knops do not extend to the back of the bow which is generally flat. The lower bow has a slight central ridge which ends with a foot-knob. There is minor pitting on a dark green patinated surface. It is structurally intact and stable. The object is in good condition.

Slide2

SF 0153 Light Polden Derivative Brooch

The brooch is mostly intact but a portion of the catch-plate is missing. The pin is intact and complete. The spring contains 18 coils including the final pin coil. The wings are decorated with two lines each with hatching to the outside of each line. The bow may have contained a similar line decoration but this in quickly lost on the surface with the best evidence on the bow head. The brooch exhibits a nice green patinated surface with minor warting and pitting. The brooch is stable and intact. It is in good condition although the pin may be considered fragile and easily snapped.

Slide3

SF 0554 Bow Brooch ??Hod Hill Variant??

The brooch has a tube rolled forward with a slot cut for a hinged pin. The axis bar appears to have been iron based on iron corrosion products inside the tube and around the hinge. The pin is partially intact and is missing approximately half of its length based on the catch-plate. The bow is vertically ribbed and ends with a foot-knob. The brooch exhibits a green patinated surface. Some corrosion material remains on the surface but does not obscure the decoration. The object is in moderate condition based on the fragile state of the pin.

Slide4

SF 0892 Hinged T-Shaped Brooch, similarities with Light Polden Derivative Brooch

The brooch head is heavily decorated with vertical ridges with varying trough depths. The axis bar is housed in an enclosed tube. The pin is hinged. Most of the pin is missing. The wings of the brooch have two area each of hatching demarcated by moulded lines. These do not extend to the back which is plain. The bow is undecorated except near the head where there is an extension of the vertical ridges which end with a single transverse line and knop. The object is in good condition. There are minor surface warts and minor pitting. There is a dark green hard patinated surface

Slide5

SF 0944 Hod Hill Brooch

The brooch was introduced into the lab with a broken pin that had to be re-adhered. The wings form a forward rolled tube to hold the axis bar. A slot has been cut to allow the pin to hinge on the axis bar. The axis bar may have been composed of iron. There are minor areas of iron corrosion on the edges of the winds and within the cut slot. The pin is partially intact. The head and wings of the pin are undecorated. The upper bow exhibits a broad central ridge with hatch marks. The lower bow is triangular in shape with circular moulded impressions grouped in 3s and 5s and look reminiscent if not so similar to grape bunches (the photomicrographs show these in greater detail). The lower bow ends in a foot-knob. The brooch was tinned with tinning remnants located along the central ridge and the edges of the upper bow and across the entirety of the lower bow and foot-knob. The brooch is in good condition. There is substantial core metal and no active corrosion. There is little warting and a dark green hard patina with areas of extruded cuprite most notable on the lower bow.

Slide6

SF 0959 Bow Brooch

This brooch exhibits characteristics of a Hod Hill Brooch. The axis bar is housed in a forward rolled head. Iron corrosion around the axis bar suggests the bar was composed of iron (also typical in Hod Hill Brooches). The pin is missing but the presence of an axis bar indicates it was hinged. The upper bow is decorated by three vertical ridges with hashing. The lower bow is decorated with transverse ridges. The bow ends at a foot-knob. Remnants of the catch-plate remain. The brooch exhibits a green patinated surface with minor warting. The brooch is in good condition.

Slide7

One of the most interesting classes of Roman artefacts is the brooch. It is an object which represents form, function and art. Examining these objects provided an opportunity to see beyond the technical and into Roman perceptions of aesthetically appealing clothing accessories. Of course, brooches are a little more than just accessories as they are required for one to remain clothed. The next post will examine enameled brooches.

 

Thumbnails for higher resolution photographs…

 

Cardiff Castle Archaeological Conservation: Roman Jewelry – Other Objects of Personal Adornment

Originally this post was going to present all the copper alloy jewelry recovered and conserved from the Cardiff Castle excavations. It was quickly realized that this would be a huge task based on the number of finds. As a result I have split the original post into three smaller posts, each looking at specific object types:  bracelets, rings and other objects. This post covers mostly pendants as identified by archaeologists prior to conservation.

The conservation goal for these objects is simply to clean for identification and preservation, and report on any discoveries. The cleaning was conducted under a binocular microscope using a fresh scalpel blade to remove soil and copper corrosion, such as malachite (a copper carbonate) and extruded cuprite (a copper oxide), to reveal the ‘original’ surface of the object. Ethanol impregnated cotton swabs were used to remove loose material from the surface. The objects were coated with two coats of 10% (v/v) Incralac in toluene after cleaning.

It should be noted that the simple acts of using a scalpel blade and cotton swabs on the archaeological materials is grounded on a foundation of understanding regarding the technology, chemistry and corrosion processes of, in this case, copper alloys. Please do not use any information contained within these blog posts as a guide on how to clean archaeological objects unless the user has a similar level of understanding, training and experience.

Objects SF 0064, SF 0285 and SF 0412 were all identified as either a pendant (or fragment thereof) or as a possible pendant. All of the objects were covered in a mixture of soil and corrosion materials. These were removed to reveal as much of the original surface as possible. In post treatment objects SF 0064 and 0412 have a similar surface composed of a friable patinated surface underlain by a thin green corrosion crust which overlays the core metal. Object SF 0064 has less patinated surface remaining then SF 0412.

Slide1Cslide3c

Object SF 0285 was cleaned to reveal a heavily warted surface and the presence of three holes as evident in the photographs. There was some question as to whether this actually represents a pendant and it is quite possible that it may be an attachment plate due to the presence of holes and the size of the object. The warts were retained as removal could result in a heavily pitted surface or even a fragmented object.

Slide2C

The final object in this blog entry object assemblage is a copper alloy pin (SF 0289). This pin actually should not be placed into this particular post as it would have had function beyond simple adornment. However I have included it here because it probably was worn on the person, serves as a segue for the next post and, finally, it had to be presented somewhere. This pin is special to me as I did not realize until I was nearly finished cleaning it that the head is actually a dollop of greenish-blue glass about the size of the small marble (I assumed it was all copper alloy). The moment of discovery was an influx of strong emotion with the initial instinct to tell someone followed by the realization that I would have to acknowledge that I did not identify it prior to cleaning (a point made moot now by presenting this to the world). The photograph of the cleaned object shows it in reflected light (as are most of the objects in this blog series) and transmitted light. The transmitted light photograph was produced by placing the object on top of a light table. One can see the under-glass extension of the copper-alloy pin into the glass by the refracted silhouette in the transmitted light photograph. The silhouette of which I refer is the dark blob in the glass slightly off-centered of the pin shaft. The long narrow shadow next to it is actually cleavage between two lobes in the glass surface. This may represent where the glass was starting to overlap itself as it was applied.

Slide4C

We delve into the mass of brooches in the next few blog posts. Below are thumbnails of the photographs provided in this post. Clicking on them will take the reader to a higher resolution image. Finally, be safe and use critical thinking during the Covid-19 lock-down.

 

Cardiff Castle Archaeological Conservation: Roman Jewelry – Finger Rings

Originally this post was going to present all the copper alloy jewelry recovered and conserved from the Cardiff Castle excavations. It was quickly realized that this would be a huge task based on the number of finds. As a result I have split the original post into three smaller posts, each looking at specific object types: bracelets, rings and other objects. This post covers finger rings which were identified as rings or finger rings by archaeologists prior to conservation. Most if not all of these are probably finger rings with the possible exceptions of SF 0348 (see below).

The finger rings recovered from excavations and conserved can fit into four broad categories based on style and object condition. It should be noted that these styles were constructed for the purpose of this blog and are not a reflection of convention in archaeology. I include object condition as a criterion for the simple reason that an incomplete finger ring may preclude it from a category that it might well fit into if complete.

The conservation goal for these objects is simply to clean for identification and preservation, and report on any discoveries. The cleaning was conducted under a binocular microscope using a fresh scalpel blade to remove soil and copper corrosion, such as malachite (a copper carbonate) and extruded cuprite (a copper oxide), to reveal the ‘original’ surface of the object. Ethanol impregnated cotton swabs were used to remove loose material from the surface. The objects were coated with two coats of 10% (v/v) Incralac in toluene after cleaning.

It should be noted that the simple acts of using a scalpel blade and cotton swabs on the archaeological materials is grounded on a foundation of understanding regarding the technology, chemistry and corrosion processes of, in this case, copper alloys. Please do not use any information contained within these blog posts as a guide on how to clean archaeological objects unless the user has a similar level of understanding, training and experience.

 

The Objects

 

Round Cross-Section Finger Rings

SF 0061, SF 0348, SF 0538, SF 0576, SF 0974

Five finger rings, either complete or fragmented (SF 0061 and SF 0348), fit into this category. All of the rings were covered in loose soil with some minor quantities of harder concreted soil and all exhibited some form of corrosion deposits on the surface. Upon cleaning, ring SF 0348 exhibited a dark green patinated surface with some pitting. The inner diameter of the ring is 30 mm (my wedding band is 19 mm inner diameter). This makes for the biggest ring in those presented here. It could be a large finger ring or possibly a harness ring. Ring is SF 0538 had similar patination and pitting to SF 0348. The surface of SF 0576 revealed similar pitting but lighter green colour. SF 0061 was similar to this but the colour is more buff. The surface of SF 0974 showed some areas of a green patinated surface but a lighter powdery textured surface underlying it was more extensive. This is not powder on the surface but rather a powdery or silty textured surface. This surface was noted on some of the bracelets mentioned in the previous post. It is not suspected of being ‘bronze disease’ as no additional ‘powder’ was produced during the several months that it was in our care. The object will be monitored to ensure that the object is not actively corroding.

Slide1C

Penannular Finger Rings

SF 0217, SF 0335

Two rings fit into the penannular (meaning the form of a ring with a small break in the circumference) category. These rings were covered in loose soil from the burial matrix. Ring SF 0217 contained a plug of dirt within the ring. This incited a slight feeling of apprehension as it gave the appearance that the plug of soil was supporting the entire structure of the ring. The condition of the uncleaned ring also fed into this fear as it was mottled light and dark green mixed with the soil on the surface. As it turns out, this was completely misleading as the ring was structurally sound (meaning it was not about to collapse) when the soil was removed. The surface consisted of a dark green patina broken by corrosion warts. The warts were retained as removal would most likely reveal pitting below. The ring is a highly eccentric ellipse in cross-section. Highfalutin words meaning generally rectangular with convex surfaces. Cleaning of Ring SF 0335 revealed a greenish-brown patinated surface with some warts. The ring is generally round in cross-section but were tapered to a point at the termini.

Slide2C

Strap Finger Ring

SF 0600

The ring had fragmented into three pieces. Each fragment was covered in soil from the burial matrix. One of the fragments also exhibited thick copper corrosion deposits. Cleaning revealed that two of the fragments could be joined. These were adhered using 40% (w/v) Paraloid B-72 in acetone. The surface is pitted with corrosion warts. The warts were retained due to the fragile nature of the ring body out of fear that the ring could fragment more. The ring is rectangular in cross-section with convex surfaces. This ring is similar to SF 0217 discussed above but was relegated to its own category due to it lacking termini.

Slide3C

Coil Finger Ring

SF 0155

This ring was covered in a layer of thick soil. Cleaning the surface revealed a coil ring composed of a single copper alloy wire coiled into a ring (as the name suggests). The surface appears to be copper carbonates overlying the copper alloy core metal. This has the same texture as mentioned above and in the last post regarding the ‘powdery-textured’ surface. This is not suspected of being ‘bronze disease’.

Slide4C

The following thumbnails are linked to higher resolution photographs.

The next post will cover other copper alloy materials possibly identified as personal adornment that were recovered from the Cardiff Castle excavations.

Cardiff Castle Excavations Archaeological Conservation: Roman Jewelry – Bracelets

Originally this post was going to present all the copper alloy jewelry recovered and conserved from the Cardiff Castle excavations. It was quickly realized that this would be a huge task based on the number of finds. As a result I have split the original post into three smaller posts, each looking at specific object types: bracelets, rings and other objects. This post covers bracelets which were identified as such by archaeologists prior to conservation.

The bracelets recovered from excavations and conserved can fit into six broad categories based on style and object condition. It should be noted that these styles were constructed for the purpose of this blog and are not a reflection of convention in archaeology. I include object condition as a criterion for the simple reason that a fragment of a bracelet may preclude it from a category that it might well fit into if complete. One work around is to just include it into said category but this would be based on an assumption made on the part of this conservator. Such assumptions in archaeology in the past have taken years to correct after they were taken as fact. It seems a better solution to report on the existing characteristics of an object without relying on assumptions which may well prove false.

The conservation goal for these objects is simply to clean for identification and preservation, and report on any discoveries. The cleaning was conducted under a binocular microscope using a fresh scalpel blade to remove soil and copper corrosion, such as malachite (a copper carbonate) and extruded cuprite (a copper oxide), to reveal the ‘original’ surface of the object. Ethanol impregnated cotton swabs were used to remove loose material from the surface. The objects were coated with two coats of 10% (v/v) Incralac in toluene after cleaning.

It should be noted that the simple acts of using a scalpel blade and cotton swabs on the archaeological materials is grounded on a foundation of understanding regarding the technology, chemistry and corrosion processes of, in this case, copper alloys. Please do not use any information contained within these blog posts as a guide on how to clean archaeological objects unless the user has a similar level of understanding, training and experience.

The Objects

Side-Notched Penannular Bracelet

SF 0316

The bracelet was recovered from excavations in two pieces and was coated in loose soil and a harder concreted soil. Removal of the surface dirt revealed small localized areas of copper corrosion and large expanses of ‘original’ surface. Some dense corrosion material was retained as removal could have further damaged the object. The bracelet fragments were adhered together using a quick curing epoxy. Removal of most of the corrosion and soil material revealed a penannular (meaning the form of a ring with a small break in the circumference) bracelet with notches along the sides. The bracelet is oviod in cross-section with the longer convex surface on the exterior (top).

Slide1 cropped

Top-Hatched Penannular Bracelet Fragment

SF 0415

This bracelet fragment was covered in loose surface soil and some small localized areas of dense copper corrosion. Removal of this material revealed a sub-rectangular cross-section with rounded edges. One terminus flattened out into a pancake-like feature. The other terminus represents a break-point in the bracelet. The top of the bracelet exhibits parallel hatching.

Slide2

Side-Notched Bracelet Fragment

SF 0202

The bracelet remains had fragmented into five pieces. Each fragment was covered in a thick layer of soil from the burial matrix. Several of the fragments also exhibited thick copper corrosion deposits. Removal of these layers revealed a nice bronze coloured surface. The surface also revealed several pits. Removal of most of the thick copper corrosion products could have easily caused the bronze coloured surface to fragment and separate from the main body. The corrosion products were retained in these areas. Examination of the surface revealed notches along the side edges of the bracelet.

Slide3

Top-Notched Bracelet Fragment

SF 0193

This is a small (< 2cm) bracelet fragment covered in loose soil material. The soil was removed to reveal the ‘original’ surface. The bracelet is ovoid in cross-section with the long curve on the exterior/top. The top is notched with broad ‘V’ cuts producing a series of facets along the upper surface. The bracelet is sub-rectangular in cross-section.

Some of the surface had fragmented while in deposition revealing a lighter green almost powdery textured surface. This ‘powder’ was not noted on the patinated surface. The ‘powder’ MAY be the first indication that the object is actively corroding. However, the lack of ‘powder’ on the surface does not support the presence of the feared ‘bronze disease’ which can completely reduce a copper alloy object to powder in a short period of time if the conditions are right. Only time and observation will reveal if the object is actually actively corroding.

Slide4 cropped

Cable-Style Bracelets

SF 1037; SF 0265; SF 0118; SF 0102

Cable-style bracelets are produced by twisting copper alloy wires into a band or cable. The individual wires are relatively weak but the cable as a whole imparts a strength to the entire structure. From a conservation point-of-view these bracelets are relatively weaker than other bracelet types based on the wiring. This served as a guide while working on the objects.

The bracelets were covered in loose soil and light green copper corrosion products where the patinated surface was missing (similar to SF 0193 discussed above). Two of the fragments reveal structures that could represent termini. Bracelet SF 0265 reveals a copper alloy wire that bends outward and over the bracelet body. This could represent a terminus or a torsion break. Bracelet SF 0118 appears to have two wire bands that encircle the bracelet (in effect tying it off) and more probably represent a terminus of a penannular bracelet. Bracelet SF 0102 represents a bracelet fragment that has been partially bent over on itself.

Slide5

Strap-Bracelet

SF 0984

This bracelet fragment was coated in loose surface soil and dense copper corrosion products. Cleaning revealed continued dense copper corrosion products, warts and pitting in the ‘original’ surface. The bracelet is sub-rectangular in cross-section with a short lobe on each upper edge of the bracelet exterior/top (see the figure). Much of the dense corrosion on the surface was retained as removal could have further damaged the object.

Slide6 cropped

 

Thumbnails are provided here. Clicking on them will open a larger resolution image for closer inspection.

The next post will cover the copper alloy rings recovered from the Cardiff Castle excavations.