Dear Ruth,
Your problem is not ridiculous but interesting and one which I too have
encountered during 30 years of preparing animal skeletons.
Here is some advice about grease and protein depletion of modern reference
bones:
My suspicion is that your over-boiling of the carcass has led to protein
depletion of the bones causing their brittleness. This may be more acute in
the case of the "flatter" bones like scapulae, ribs and parts of the skull.
The endochondral (e.g. limb) bones tend to be more resistant to boiling. I
would doubt whether grease has much effect on the strength of bone tissue.
I also fear that grease left in bones is detrimental due to long-term
bacterial decay leading to lowering of the pH. I am unsure whether the acids
are bacterial metabolites or simply fatty acids derived from the fat
itself - perhaps both. Either way, the lowered pH leads, over the years, to
softening of the bone. For this reason (as well as smell and health
considerations) I always advise complete degreasing of bones (you may find
it easiest and most efficient to use acetone).
So, rather than returning grease to your now brittle bones, you might think
in terms of returning protein or some hardener to the bone. In the past I
have re-inforced brittle bone with an acetone solution of poly-methyl
methacrylate (perspex) - a substance also known in the French world of
conservation as "Rhodopas". It comes in crystal form, and, if I remember
correctly, it is not expensive. You should be able to purchase it from any
of the large chemical firms like ICI. Alternatively (I have never done this)
you could try returning the protein to your brittle bones by immersing them
in a hot aqueous solution of "carpenters glue" (this is of course the
protein extracted from animal bones). It too comes in crystal form and needs
to be dissolved in hot water. Warning: it stinks! If you try this option I
would be most interested in knowing if and how well it works.
Our preparation method is now described in several publications:
the penultimate ICAZ newsletter,
Circaea 8,2 (1992),
The Rubber Band Society Gazette 1,1 (2001) and
in Spanish in Archaeofauna 12 (2003).
If you cannot gain access to these publications I can send you electronic
versions of the first and third.
Good luck and let me know how you get on if you try the "glue" method,
simon davis
Instituto Português de Arqueologia
Avenida da Índia 136
P-1300-300 Lisboa
Portugal
----- Original Message -----
From: "Ruth Carden" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, January 22, 2004 4:59 AM
Subject: [ZOOARCH] re putting grease back into bones!
> Hello all and happy new year!
> I hope this message finds ye all well and enjoying life.
>
> A quick question for ye people of bones.......
>
> Does anyone know of a method/way of putting back some grease/fat into
> bones? These bones have been 'overdone' during a simmering procedure in
> the recent past and basically need some grease put back to decrease the
> brittleness factor. (Its of a deer from my own personal collection, due
> to sickness on my part, the ribs and thoracic vertebrae have been over
> done).
>
>
> Thanks and hopefully someone has had past experience and can share.
> Otherwise I will set of my own set of 'grease-experiments'.
>
> Looking forward to any response and forgive me if the question sounds
> ridiculous.
>
> Kind regards
> Ruth
>
> --------------------------------------
> Ruth F. Carden B.Sc.
> Zoology Department
> National University of Ireland, Dublin
> Belfield, Dublin 4
> Ireland
> Tel: (+)353-1-7162261
> www.ucd.ie/zoology
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