[dsfranca]

Hi guys,
I would like to know if any of you knows a method to determine the time it takes for a given substance to decompose. I would really like to perform such experiment, but I was not able to find anything, and I am sure this method exists, as everyone has already seen a table like this one: http://www.qldlitter.com/pdfs/wastea3.pdf .
I would need to perform the experiment for Alimunium, wood and iron.
It would already help if you could tell me if I am using the right terminology (degradation/decomposition) or the name of this field of study, as in this way I could refine my search.
Thank you in advance!

[dsfranca]

I just realized that Aluminium and Iron are pure elements and dont decompose,
but I am still not sure about the wood. I mean, I could just leave the wood in a environment that is ideal for bacterial growth and then measure the mass (or should I measure something else, such as volume?) of the piece of wood as time passes and then infer when the wood will be totally decomposed. As I am only interested in one specific piece of wood, it only matters how much time it takes for this piece to decompose, so this eliminates lots of variables.
But my problem is that, as there is varnish on this specific piece, it will not normally decompose. How could I measure how much time it would take for the varnish to loose its effect?
Thanks for helping me out!