<div dir="ltr">Dear David and Sonia,<div><br></div><div>the rivets were bronze so the green colouration could well be coming from the rivets' oxidation. However this staining was limited to the surface (surface of the cortical bone) and not in sub-surface layers. Therefore we assume that the colouration was done deliberately. </div>
<div>Based on our data, a relationship with a certain recipe wasn't possible but we think it was a copper based product (so called <i>verdigris</i>, basic copper acetate<font face="arial, helvetica, sans-serif">, Cu(OH)<font size="1">2</font> · (CH<font size="1">3</font>COO)<font size="1">2</font> · 5 H<font size="1">2</font>O). </font></div>
<div><br></div><div>You also mention the use of urine, which was frequently used for producing metal salt based pigments. The urine itself induces the corrosion on the copper sample. After it is corroded, one can scratch of the crystals, grind them to the desired particle size, add a medium (e.g. oil, wax) et voilà, a green pigment. See these two pictures from an experiment I have done in 2003. </div>
<div><img src="cid:ii_1456fa2d02209f8b" alt="Inline images 2" width="343" height="407" style="margin-right: 0px;"> <img src="cid:ii_1456fa2cc57b1a1d" alt="Inline images 1" width="403" height="403" style="margin-right: 0px;"></div>
<div>On the first picture you can see small slabs of copper hanging above vinegar (I could have well replaced the vinegar with urine). There should be no contact between the copper slabs and the fluid. The vapours of the fluid induces the corrosion process. On the second picture you can see the actual scrapings of the copper acetate crystals, which are ready to use. One often read in historical recipes that the jar should be buried in horse dong. The bacterial activity in the latter produces heat (sometimes +70° Celcius) and therefore it significantly increases the corrosion process and reduces the production time. <br>
</div><div><br></div><div><br></div><div>Sonia: </div><div>the object you have mailed also has the same green colouration as I would expect from an object coloured with a basic copper acetate based pigment. What draws my attention is the brownish decolouration on both sides of that object. Copper acetate is quite unstable and when exposed to light and a 'high degree of humidity' it turns into the more stable molecule copper oxide, which is brown to black.</div>
<div><br></div><div><br></div><div>Yours,</div><div>Vincent Cattersel</div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On 17 April 2014 13:36, SA O'Connor <span dir="ltr"><<a href="mailto:S.Oconnor@bradford.ac.uk" target="_blank">S.Oconnor@bradford.ac.uk</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear David,<br>
<br>
Back in the 1980s, when I was at the York Archaeological Trust we were involved in providing green stained objects for an undergraduate dissertation by a University of Bradford, Archaeological Sciences, student (surname of Edwards, I think) to look at exactly this question. Some objects seemed to be accidentally stained (often very patchy) whilst others were intensely and evenly stained and were considered to be deliberately coloured. All were analysed by XRF and copper/bronze proved to be the basis of all the staining solutions used.<br>
<br>
In my more recent work I have documented historical pieces, such selected elements of bone and antler in box and gun inlays and bone and ivory cutlery handles(and working waste from cutlers) that are undeniably deliberately stained.<br>
<br>
I attach a low resolution image an archaeological example, a buckle at the Yorkshire Museum that I am convinced is deliberately stained in this way.<br>
<br>
All the best,<br>
<br>
Sonia<br>
<br>
Quoting David Constantine <<a href="mailto:dkconstantine@btinternet.com" target="_blank">dkconstantine@btinternet.com</a>><u></u>:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
I am aware that copper (or alloys) is often cited as a green dye for (such as in MacGregor 1985), but I believe there is also recipes from the Mappae Clavicula that use weld, urine and "lulax" to dye bone green, so I was curious to see if any chemical analysis has been performed to determine how the green has been achieved.<br>
<br>
Looking at the zoomed images, I believe the rivets are iron.<br>
<br>
Regards, <br>
<br>
David Constantine <br>
<br>
<br>
______________________________<u></u>__<br>
From: Kordula Gostencnik <<a href="mailto:kgosten@gmail.com" target="_blank">kgosten@gmail.com</a>><br>
To: "Mailing list for archaeologists of the research group for the study of object and waste of bone, antler. ivory and horn." <<a href="mailto:bonetools@listserv.niif.hu" target="_blank">bonetools@listserv.niif.hu</a>><br>
Sent: Wednesday, 16 April 2014, 20:21<br>
Subject: Re: [Bonetools] Colouring bone<br>
<br>
<br>
<br>
Green stains are normally caused by bronze objects or copper alloy scrap associated with worked bones in the soil. Are the rivets all made from iron or also from bronze?<br>
<br>
Kordula<br>
<br>
<br>
<br>
2014-04-16 17:15 GMT+02:00 Dave Constantine <<a href="mailto:dkconstantine@btinternet.com" target="_blank">dkconstantine@btinternet.com</a>><u></u>:<br>
<br>
Thank you all for your replies.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Vincent, the green stained comb you linked is rather interesting. Do you<br>
</blockquote>
know what the green pigment is? Also, looking at the images, it seems that it is<br>
no more than a surface colourant with little penetration, is this correct?<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Thank you for your suggestion of minium, I was at a loss about what it<br>
</blockquote>
could be. It is not a fresh find, it was originally discovered in the 1960s (or<br>
possibly 1970s) and mounted on a card for display. To the best of my knowledge<br>
though, the colouring is original, though it is possible that the surface was<br>
also coloured and this has simply failed to survive.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
I have Arthur MacGregor’s book, and very useful it is too on the matter of<br>
</blockquote>
colouring.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Regards,<br>
<br>
David Constantine<br>
<br>
<br>
<br>
From: Vincent Cattersel<br>
Sent: Wednesday, April 16, 2014 2:03 PM<br>
To: Mailing list for archaeologists of the<br>
</blockquote>
research group for the study of object and waste of bone, antler. ivory and<br>
horn.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Subject: Re: [Bonetools] Colouring bone<br>
Dear all,<br>
<br>
this is a first where I might be able to contribute to this group, but I'm<br>
</blockquote>
happy to do so:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
In 2008 I have conserved and restored 8 bone/antler combs from the<br>
</blockquote>
Merovingian period at the Royal Institute for Cultural Heritage (Brussels,<br>
Belgium). These combs are currently preserved at the Royal Museums of Art and<br>
History in Brussels, Belgium.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Here you can find pictures of a few of them (click on the pictures to get a<br>
</blockquote>
zoomable high resolution image):<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<a href="http://balat.kikirpa.be/photo.php?path=X026849&objnr=20042741" target="_blank">http://balat.kikirpa.be/photo.<u></u>php?path=X026849&objnr=<u></u>20042741</a><br>
<br>
<a href="http://balat.kikirpa.be/photo.php?path=X035781&objnr=20052916" target="_blank">http://balat.kikirpa.be/photo.<u></u>php?path=X035781&objnr=<u></u>20052916</a><br>
</blockquote>
(green staining on the surface, carbon black in the circular<br>
motives)<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
<a href="http://balat.kikirpa.be/photo.php?path=X026845&objnr=20052917" target="_blank">http://balat.kikirpa.be/photo.<u></u>php?path=X026845&objnr=<u></u>20052917</a><br>
<br>
<a href="http://balat.kikirpa.be/photo.php?path=X038388&objnr=20052919" target="_blank">http://balat.kikirpa.be/photo.<u></u>php?path=X038388&objnr=<u></u>20052919</a><br>
<br>
<a href="http://balat.kikirpa.be/photo.php?path=X035783&objnr=20052922" target="_blank">http://balat.kikirpa.be/photo.<u></u>php?path=X035783&objnr=<u></u>20052922</a><br>
<br>
<br>
Some of these where coloured and stained with green and carbon black. We<br>
</blockquote>
used µ-XRF, µ-RAMAN and SEM(-EDX) to analyse the stains and the carbon black<br>
particles.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
So staining and colouring isn't that uncommon, as you probably already<br>
</blockquote>
know.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
When I look at the picture, I can see that the red is slightly orange,<br>
</blockquote>
which makes me think about the pigment lead red (also called 'minium' or lead<br>
tetra-oxide, Pb3O4). This isn't a<br>
surprise since it is one of the oldest known vivid red pigments (except for some<br>
iron oxide pigments derived from hematite and red earth or cinnabar (HgS),<br>
however they all are true 'reddish' in colour and lack the hint of orange).<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
<br>
<br>
Some simple identification techniques for minium are:<br></div></div>
* Ultraviolet fluorescence (if minium, it minium it should show a dark red colouration);<br>
<br>
* Infrared False Color which should gives the observed minium a yellow-brown colour. Analytical techniques:<div class=""><br>
In case you have the oppurtunity to<br>
</div></blockquote><div class="">
analyse it with RAMAN, you can find a reference spectrum here.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
For<br>
</blockquote>
a reference spectrum of minium using XRF: here.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
<br>
<br>
Another thing is the question whether this die was excavated and brought<br>
</blockquote>
directly to your collection or was it once part of a (private)collection and<br>
excavated a long time ago.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
This is an important question since it could provide an answer to whether<br>
</blockquote>
or not this colouration is original.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I know from my experiences with the conservation of precious ivory objects<br>
</blockquote>
that they are often repainted (repolychromed) throughout time, even though their<br>
iconography or typology gives us reasons to believe that they originally weren't<br>
polychromed or not polychromed in such manner as they are today.<br>
</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="">
<br>
To get back on the minium pigment, more information can be found in:<br></div>
* Eastaugh, N., Walsh, V., Chaplin, T., & Siddall, R. (2008). Pigment Compendium - A Dictionary and Optical Microscopy of Historical Pigments. Oxford: Butterworth-Heinemann.<br>
<br>
* Feller, R. L., Gettens, R. J., & Chase, W. T. (1993). Vermilion and Cinnabar. In R. Ashok, Artists' Pigments - A Handbook of Their History and Characteristics. (Vol. II, pp. 159-182). Washington-London: National Gallery of Art.<div>
<div class="h5"><br>
<br>
Another book I can recommend on staining and colouring bone materials is:<br>
</div></div></blockquote><div><div class="h5">
McGregor. A. (1985) Bone, Antler, Ivory & Horn: The Technology of Skeletal<br>
Materials Since the Roman Period.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I don't have it here with me for the moment, but as you wish, I can always<br>
</blockquote>
go through it to find more information on red staining or colouring.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Yours,<br>
<br>
Vincent Cattersel<br>
<br>
Drs.<br>
</blockquote>
VINCENT CATTERSEL<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Doctoral researcher<br>
Universiteit<br>
</blockquote>
Antwerpen / University of Antwerp<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Faculteit<br>
</blockquote>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Opleiding<br>
</blockquote>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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</blockquote>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<br>
On 15 April 2014 09:06, David Constantine <<a href="mailto:dkconstantine@btinternet.com" target="_blank">dkconstantine@btinternet.com</a>> wrote:<br>
<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hello All,<br>
<br>
Attached is an image of a (probably) Saxon bone/antler die. As can be seen, there is reddish pigmentation in the decoration. I have looked around for similar colouring and with the exception of a "lucet" from London I cannot seem to find anything similar, just totally stained objects e.g. the belt buckle from York. Does anyone here know of any Early Medieval dated bone artefacts that are either entirely stained/dyed or have coloured decoration such as this?<br>
<br>
Regards,<br>
<br>
David<br>
</blockquote></blockquote>
Constantine<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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