[Bonetools] Colouring bone
Vincent Cattersel
vincent.cattersel at gmail.com
Tue Apr 22 11:54:25 CEST 2014
Dear all,
Dear Sonia,
what you are writing is indeed very interesting:
*On the bone and ivory objects I have examined in detail the green
colouration is definitely a staining and not the application of a
particulate pigment in a medium. Perhaps copper acetate is involved at
some stage in the process of corroding the copper but once the copper is in
solution it has to combines with the mineral component of the bone to
produce a permanent staining. The result is a stain that seems to have more
the colour and stability of malacite (or at least something chemically
similar to this) than copper acetate. *(Sonia O'Connor, April 17 2014)
I've restored and conserved several medieval ivory objects throughout the
years and I have observed this phenomenon up close. Please check the
following objects I have studies and conserved in 2009-2010:
- Ivory and bone polyptique, Sint-Jans Hospitaal Museum, Bruges (B):
http://balat.kikirpa.be/photo.php?path=X028145&objnr=109084#related
- Virgin and Child, Royal Museum of Art and History, Brussels (B):
http://balat.kikirpa.be/photo.php?path=X040908&objnr=20054149#related
A green staining is often the result of the migration of copper-ions
towards the ivory. In both cases I have referred to above, this staining is
related to the use of the pigment azurite (a basic copper carbonate). On
the given examples you can see that in those areas where the azurite
pigment has disappeared, a greenish/yellowish staining of the ivory remains
(e.g. inner side of the mantle or the cloak). There are some articles on
this matter, if one is interested I can send the references this evening.
It might not be very vivid or intense green(ish) but the staining is there
and I assume similar effects are possible when the support is made of bone.
Of course I'm comparing two objects that were never buried with ones who
were buried so I can imagine that the migration of ions and so the result
of the staining might even be more intense when buried for hundreds of
years.
As for the case of the two Merovingian combs I think that those green
surfaces did not remain completely green as the result of copper-ion
migration towards the bone material. This because we have clearly
identify copper-based particles on the bone's surface (SEM(-EDX)).
Therefore indicating the use of a pigment (such as copper acetate) and a
medium. So for the latter two the staining of the bone due to ion-migration
might have been a side-effect but unfortunately I am not able to confirm
this.
Regards,
Vincent Cattersel
On 22 April 2014 10:24, François Poplin <poplin at mnhn.fr> wrote:
> We have had allready such a "conference" a coupkle of years go. I
> recall you :
>
> *cuivre (conservation au) *: 167 (cuirs), 179 (épingles corne), 228, 246
>
>
> 167 POPLIN, F., 1992 - Des cuirs de l'Age du Bronze conservés par le
> cuivre. *Autour du cuir, Rencontres archéologiques de Guiry 1991* (1992),
> Musée archéol. dép. du Val d'Oise, 97-102, 2 figs.
>
> 179 POPLIN F., 1993 - La corne des épingles,* in* : *Le trésor
> d’Eauze*, sous la dir. de D. Schaad, Toulouse, A.P.A.M.P., 359-361, 3 figs
> .
>
> 228 POPLIN F., 1999 - La main verte, *Trésors méconnus du Musée de
> l'Homme*, Paris, Cherche-Midi, 141.
>
> 246 POPLIN F., 2001 - De Lebeuf à Buffon : la main verte de
> Merry-sur-Yonne, *Bull. Soc. nat. des Antiquaires de France*, 1997
> (2001), 282-288, 1 fig.
>
>
> You can see "verdigrised" ivory knife handles in the Eauze treasury
> typing "trésor eauze" on Google. The best in that case is* 2 preserved
> horn pins (I mean : made of horn of cattle, keratin).*
>
>
>
> * ostrich eggs : *202, 239 *(with "batik" technic, using etching)*
>
>
> 202 POPLIN F., 1995 - Sur le polissage des oeufs d'autruche en
> archéologie, *Archaeozoology of the Near East, II, *126-139, 5 fig.
>
>
> 239 POPLIN F., 2000 - Œufs d'autruche décorés grecs et étrusques :
> technique et diffusion, *in *: *L'artisanat en Grèce ancienne. Les
> productions, les diffusions, Coll. EFA-MOM, Lyon, 10-11 déc. 1998*,
> Lille, Univ. Lille 3, 127-143, 14 fig.
>
> No pdf, soory ; but I can send papers...
>
>
>
> Le 17/04/2014 20:10, Kordula Gostencnik a écrit :
>
> ... and the easiest way to dye textiles green is to put sour milk into a
> copper vessel along with the textile - I think the effect is also due to
> the chemical reaction which produces verdigris, but I am completely
> unfamiliar with this science. This is one of the rare methods of direct
> dyeing where no mordant is necessary for the textiles. We tried it out with
> cloth and it is astonishing how it works. John Peter Wild refers to it in
> his book "Textile produciton in the north-western Roman provinces" - sorry
> I can't give the full reference. Might this also work with bones?
>
> Sincerly
> Kordula
>
>
> 2014-04-17 17:07 GMT+02:00 SA O'Connor <S.Oconnor at bradford.ac.uk>:
>
>> Dear All,
>>
>> I agree this is a fascinating topic and we aught to also consider traces
>> of gilding and adhesives, and dressings such as waxes and oils.
>>
>> I am familiar with copper acetate discolouration in paintings and works
>> of art on paper and this goes very brown with time. I don't think this is
>> the case on this bone buckle. If the colour were due to the deterioration
>> over time of copper acetate then I would have expected the changes to be
>> seen generally over the surface of the object and not restricted to
>> specific features. The brown appears to be due to the underlying colour
>> variation in the bone - the stripe on the back, for instance, is an area of
>> unworked endosteal surface of the longbone from which the buckle is cut.
>> Perhaps the colour differences are due to the staining reacting with
>> variable amounts of fatty material in the surface of the worked and
>> unworked bone? I would be interested to hear anyone's thoughts on this.
>>
>> On the bone and ivory objects I have examined in detail the green
>> colouration is definitely a staining and not the application of a
>> particulate pigment in a medium. Perhaps copper acetate is involved at
>> some stage in the process of corroding the copper but once the copper is in
>> solution it has to combines with the mineral component of the bone to
>> produce a permanent staining. The result is a stain that seems to have more
>> the colour and stability of malacite (or at least something chemically
>> similar to this) than copper acetate.
>>
>> I do not know what luck I will have in chasing the thesis I mentioned but
>> I will try to do this after Easter. I do also have some copies of recent
>> historic publications that detail bone staining processes that I have
>> always meant to read and I will try to find time to look at these too, but
>> probably not until mid May.
>>
>> Are you aware of the work that has been going on at the British Museum to
>> look for traces of colour on the Lewis Chessmen? I am not sure how far
>> they have got with this but I do know some of the people involved.
>>
>> All the best,
>>
>> Sonia
>>
>> Quoting Vincent Cattersel <vincent.cattersel at gmail.com>:
>>
>> Dear David and Sonia,
>>>
>>> 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.
>>> Based on our data, a relationship with a certain recipe wasn't possible
>>> but
>>> we think it was a copper based product (so called *verdigris*, basic
>>> copper
>>>
>>> acetate, Cu(OH)2 · (CH3COO)2 · 5 H2O).
>>>
>>> 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.
>>> [image: Inline images 2] [image: Inline images 1]
>>> 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.
>>>
>>>
>>> Sonia:
>>> 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.
>>>
>>>
>>> Yours,
>>> Vincent Cattersel
>>>
>>>
>>>
>>> On 17 April 2014 13:36, SA O'Connor <S.Oconnor at bradford.ac.uk> wrote:
>>>
>>> Dear David,
>>>>
>>>> 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.
>>>>
>>>> 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.
>>>>
>>>> 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.
>>>>
>>>> All the best,
>>>>
>>>> Sonia
>>>>
>>>> Quoting David Constantine <dkconstantine at btinternet.com>:
>>>>
>>>> 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.
>>>>>
>>>>> Looking at the zoomed images, I believe the rivets are iron.
>>>>>
>>>>> Regards,
>>>>>
>>>>> David Constantine
>>>>>
>>>>>
>>>>> ________________________________
>>>>> From: Kordula Gostencnik <kgosten at gmail.com>
>>>>> To: "Mailing list for archaeologists of the research group for the
>>>>> study
>>>>> of object and waste of bone, antler. ivory and horn." <
>>>>> bonetools at listserv.niif.hu>
>>>>> Sent: Wednesday, 16 April 2014, 20:21
>>>>> Subject: Re: [Bonetools] Colouring bone
>>>>>
>>>>>
>>>>>
>>>>> 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?
>>>>>
>>>>> Kordula
>>>>>
>>>>>
>>>>>
>>>>> 2014-04-16 17:15 GMT+02:00 Dave Constantine <
>>>>> dkconstantine at btinternet.com
>>>>> >:
>>>>>
>>>>> Thank you all for your replies.
>>>>>
>>>>>
>>>>>> Vincent, the green stained comb you linked is rather interesting. Do
>>>>>> you
>>>>>>
>>>>>> know what the green pigment is? Also, looking at the images, it seems
>>>>> that it is
>>>>> no more than a surface colourant with little penetration, is this
>>>>> correct?
>>>>>
>>>>>
>>>>>> Thank you for your suggestion of minium, I was at a loss about what it
>>>>>>
>>>>>> could be. It is not a fresh find, it was originally discovered in the
>>>>> 1960s (or
>>>>> possibly 1970s) and mounted on a card for display. To the best of my
>>>>> knowledge
>>>>> though, the colouring is original, though it is possible that the
>>>>> surface
>>>>> was
>>>>> also coloured and this has simply failed to survive.
>>>>>
>>>>>
>>>>>> I have Arthur MacGregor’s book, and very useful it is too on the
>>>>>> matter
>>>>>> of
>>>>>>
>>>>>> colouring.
>>>>>
>>>>>
>>>>>> Regards,
>>>>>>
>>>>>> David Constantine
>>>>>>
>>>>>>
>>>>>>
>>>>>> From: Vincent Cattersel
>>>>>> Sent: Wednesday, April 16, 2014 2:03 PM
>>>>>> To: Mailing list for archaeologists of the
>>>>>>
>>>>>> research group for the study of object and waste of bone, antler.
>>>>> ivory
>>>>> and
>>>>> horn.
>>>>>
>>>>> Subject: Re: [Bonetools] Colouring bone
>>>>>> Dear all,
>>>>>>
>>>>>> this is a first where I might be able to contribute to this group, but
>>>>>> I'm
>>>>>>
>>>>>> happy to do so:
>>>>>
>>>>>
>>>>>> In 2008 I have conserved and restored 8 bone/antler combs from the
>>>>>>
>>>>>> Merovingian period at the Royal Institute for Cultural Heritage
>>>>> (Brussels,
>>>>> Belgium). These combs are currently preserved at the Royal Museums of
>>>>> Art
>>>>> and
>>>>> History in Brussels, Belgium.
>>>>>
>>>>> Here you can find pictures of a few of them (click on the pictures to
>>>>>> get a
>>>>>>
>>>>>> zoomable high resolution image):
>>>>>
>>>>> http://balat.kikirpa.be/photo.php?path=X026849&objnr=20042741
>>>>>>
>>>>>> http://balat.kikirpa.be/photo.php?path=X035781&objnr=20052916
>>>>>>
>>>>>> (green staining on the surface, carbon black in the circular
>>>>> motives)
>>>>>
>>>>>
>>>>>> http://balat.kikirpa.be/photo.php?path=X026845&objnr=20052917
>>>>>>
>>>>>> http://balat.kikirpa.be/photo.php?path=X038388&objnr=20052919
>>>>>>
>>>>>> http://balat.kikirpa.be/photo.php?path=X035783&objnr=20052922
>>>>>>
>>>>>>
>>>>>> Some of these where coloured and stained with green and carbon black.
>>>>>> We
>>>>>>
>>>>>> used µ-XRF, µ-RAMAN and SEM(-EDX) to analyse the stains and the
>>>>> carbon
>>>>> black
>>>>> particles.
>>>>>
>>>>>
>>>>>> So staining and colouring isn't that uncommon, as you probably already
>>>>>>
>>>>>> know.
>>>>>
>>>>>
>>>>>> When I look at the picture, I can see that the red is slightly orange,
>>>>>>
>>>>>> which makes me think about the pigment lead red (also called
>>>>> 'minium' or
>>>>> lead
>>>>> tetra-oxide, Pb3O4). This isn't a
>>>>> surprise since it is one of the oldest known vivid red pigments (except
>>>>> for some
>>>>> iron oxide pigments derived from hematite and red earth or cinnabar
>>>>> (HgS),
>>>>> however they all are true 'reddish' in colour and lack the hint of
>>>>> orange).
>>>>>
>>>>>
>>>>>>
>>>>>> Some simple identification techniques for minium are:
>>>>>> * Ultraviolet fluorescence (if minium, it minium it should
>>>>>> show
>>>>>> a dark red colouration);
>>>>>>
>>>>>> * Infrared False Color which should gives the observed minium
>>>>>> a
>>>>>> yellow-brown colour. Analytical techniques:
>>>>>>
>>>>>> In case you have the oppurtunity to
>>>>>>
>>>>>> analyse it with RAMAN, you can find a reference spectrum here.
>>>>>
>>>>> For
>>>>>>
>>>>>> a reference spectrum of minium using XRF: here.
>>>>>
>>>>>
>>>>>>
>>>>>>
>>>>>> Another thing is the question whether this die was excavated and
>>>>>> brought
>>>>>>
>>>>>> directly to your collection or was it once part of a
>>>>> (private)collection
>>>>> and
>>>>> excavated a long time ago.
>>>>>
>>>>> This is an important question since it could provide an answer to
>>>>>> whether
>>>>>>
>>>>>> or not this colouration is original.
>>>>>
>>>>> I know from my experiences with the conservation of precious ivory
>>>>>> objects
>>>>>>
>>>>>> that they are often repainted (repolychromed) throughout time, even
>>>>> though their
>>>>> iconography or typology gives us reasons to believe that they
>>>>> originally
>>>>> weren't
>>>>> polychromed or not polychromed in such manner as they are today.
>>>>>
>>>>>
>>>>>> To get back on the minium pigment, more information can be found in:
>>>>>> * Eastaugh, N., Walsh, V., Chaplin, T., & Siddall, R. (2008).
>>>>>> Pigment Compendium - A Dictionary and Optical Microscopy of
>>>>>> Historical
>>>>>> Pigments. Oxford: Butterworth-Heinemann.
>>>>>>
>>>>>> * 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.
>>>>>>
>>>>>>
>>>>>> Another book I can recommend on staining and colouring bone materials
>>>>>> is:
>>>>>>
>>>>>> McGregor. A. (1985) Bone, Antler, Ivory & Horn: The Technology of
>>>>> Skeletal
>>>>> Materials Since the Roman Period.
>>>>>
>>>>> I don't have it here with me for the moment, but as you wish, I can
>>>>>> always
>>>>>>
>>>>>> go through it to find more information on red staining or colouring.
>>>>>
>>>>>
>>>>>> Yours,
>>>>>>
>>>>>> Vincent Cattersel
>>>>>>
>>>>>> Drs.
>>>>>>
>>>>>> VINCENT CATTERSEL
>>>>>
>>>>> Doctoral researcher
>>>>>> Universiteit
>>>>>>
>>>>>> Antwerpen / University of Antwerp
>>>>>
>>>>> Faculteit
>>>>>>
>>>>>> Ontwerpwetenschappen / Faculty of Design Sciences
>>>>>
>>>>> Opleiding
>>>>>>
>>>>>> conservatie-restauratie / Conservation Studies
>>>>>
>>>>> Blindestraat
>>>>>>
>>>>>> 9
>>>>>
>>>>> B-2000
>>>>>>
>>>>>> Antwerpen
>>>>>
>>>>> T +32 3 213 71
>>>>>>
>>>>>> 34 | F +32 3 213 71 35 <%2B32%203%20213%2071%2035>
>>>>>
>>>>> vincent.cattersel at uantwerpen.be
>>>>>> www.uantwerpen.be
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 15 April 2014 09:06, David Constantine <
>>>>>> dkconstantine at btinternet.com>
>>>>>> wrote:
>>>>>>
>>>>>>
>>>>>> Hello All,
>>>>>>
>>>>>>>
>>>>>>> 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?
>>>>>>>
>>>>>>> Regards,
>>>>>>>
>>>>>>> David
>>>>>>>
>>>>>>> Constantine
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>>>
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>>>>>>>
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>>>>>>
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>>>>>>>
>>>>>>>
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>
> --
> François POPLIN
>
> Directeur honoraire de l’UMR 7209 Archéozoologie, Archébotanique : sociétés, pratiques et environnements
>
> Responsable du Séminaire d'Anthropozoologie
>
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