For Your Information

Remodelled !? manufactured from old pulverised clay terra cotta?
Bonding agent - resins suspected/detected in terra cotta, what does this
mean?
Varying clay, varying clay colours, what does this tell us about the object
made of fired clay? Belonging of varying parts e.g. head to body, have original
parts being joined, or not ?

These questions which have been occupying and influencing the Asian and
African art market intensively, require urgent clarification and remedying. The
thermoluminescence test "T L" can detect the age of fired clay, for the other
points and questions, scientific, neutral analysis procedures are of assistance.

I will be issuing shortly an extensive article which I have prepared together
with Prof. Dr. Klein of the University of Koblenz "Höhr-Grenzhausen"- faculty
"Ceramic and Glass" on this subject and the entire complex of questions
mentioned above and below.

To merely claim "Varying clay and varying colours were determined", does
not prove from a ceramic/technical point of view that an object must have
been manufactured from varying parts.

The fact that parts of an object "belong" to the entire object can largely be
clarified by the procedure which I will now briefly describe.

The claim or proof that resin bonding agents are in the structure of terra
cotta, do not prove that an object was manufactured from old pulverised terra
cotta.

Reliable proof can be provided with the following method of examination in
the course of an overall test report:

Structural analysis using a light microscopy and scanning electron
microscopy REM, chemical analysis with energy-dispersive X-ray analysis,
thermal gravimetric analysis and differential thermal analysis - TG + DTA
and heating microscopy.

A list of the procedures and representations of measurements are enclosed
in the annex.

The following statements can be made:

A. This is a fired ceramic structure = terra cotta

B. This is not a fired structure of pulverised substances!

C. This is a ceramic structure with portions of bonding stabilising agents !
As far as C is concerned, this may be a case of supplementary measures
which are absolutely necessary, e.g. to prevent terra cotta which was fired
at too low a heat from disintegrating (risk of ground/air transport) or it is a
conservation measure to maintain/supplement the surface.

Should you have any questions, suggestions or wish to exchange views,
obtain further information or are just interested in the publication which I
will be issuing in Cupertino with the University of Koblenz, please do not
hesitate to contact me.

Kind regards,
Your Ralf Kotalla