dating the age of wood

Dear all,
In this forum I often find the question about the age of pieces. This question is of course very hard to answer - esp. for someone like me who loves tribal art but is far away from being an expert.To get answers on questions like 'how' old or 'is it authentic' I sometimes take a sample of wood of a piece of mine and send it to the MUSEO D'ARTE E SCIENZA (http://www.museoartescienza.com/). They there make an IR SPECTROSCOPY, a method to date the age of the wood by means of Molecular Spectroscopy.
However there seems to be two problems with this method: First it is not so clear how exact the measurement is. And second they measure the age of the wood but it could be that someone has made a new piece of art by using old wood. To avoid the second point, the MUSEO D'ARTE E SCIENZA does two measurements comparing the spectroscopic results of the outer layer of the wood with those of wood taken from inside the object. I personally take always only one sample.
The reason for my post now is to start a discussion about this measurement. For example:
1. You can find some of my pieces here which they have tested for me. The age of the pieces according to the MUSEO D'ARTE E SCIENZA are (plus/minus 5 to 8 years):


Yoruba pot: 1908


Bulul (Ifugao): Before 1920


IBO: 1932


Baule: 1942


Dan: 1956

Could that be? Do the pieces or some of them fit to the age or are there any discrepancies? What is your opinion?
2. Do you have any experiences with this method which you can share? Maybe you can even show some pieces of your own which you have tested?

Thanks to all
Ingo

Hi Ingo

Thanks for the very interesting post. I own a copy of that museum's handbook on identifying fakes, but I'm not familiar with spectroscopic dating of wood. I'll try to find time to chase down some information on that tomorrow.

Regards

Steve Price

Hi Ingo

I did a little search for information about IR spectroscopic dating of wood. Here's a link to the best source that I found.

With certain limitations, mostly related to the type of wood, the method is said to be remarkably accurate. To get the age of a piece of sculpture, though, you really should use two sample: one from the surface and one from deeper within the piece. In some pieces, the ages derived from spectroscopy and the opinions of recognized experts were compared, and were said to always be very close.

I do have a serious reservation about the method, which is that every report on it that I found was by the inventor of the method, who also holds the patents that give him exclusive rights to use it. I found no independent confirmation that it works as claimed. The reports that expert opinion and IR spectroscopy gave results that were in agreement didn't have enough detail to persuade me that they are reliable, and I don't think the laboratory that holds exclusive rights to use and market testing by this method are sufficiently free of conflict of interest for their claims to be accepted uncritically.

I'm also a bit bothered by the fact that no mention is made of moisture content (or, if it's mentioned, I missed it). IR spectroscopy is made nearly impossible by the presence of even traces of water in samples.

That's my initial take on it. I'll try to dig deeper.

Regards

Steve Price

Hi Steve,
Thank you for your reply. I can totally follow your reservation about the method. When I asked people about it I got 3 reactions:
1. I believe them
2. Of 5 measurements only 4 are okay
3. I don't trust them.
But no one really had any proves for his opinion - neither a positive nor a negative one.
Therefore I'm very curious about the contributions in this Forum.
Ingo