Editing Chestnut (section)

===Leather===
Chestnut wood is a useful source of natural tannin and was used for tanning leather before the introduction of synthetic tannins.<ref name=edlin/> On a 10% [[moisture basis]], the bark contains 6.8% tannin and the wood 13.4%.<ref name=Rottsieper>Rottsieper, E. H. W. ''Vegetable Tannins''. The Forestal Land, Timber and Railways Co. Ltd. 1946. Cited in ''Plants for a Future''.</ref> The bark imparts a dark color to the tannin, and has a higher sugar content, which increases the percentage of soluble non-tans, or impurities, in the extract; so it was not employed in this use.<ref name=palimpsest>[http://palimpsest.stanford.edu/don/dt/dt0668.html Chestnut] in Search Conservation OnLine.</ref> Chestnut tannin is obtained by hot-water extraction of chipped wood. It is an ellagic tannin and its main constituents are identified by [[castalagin]] (14.2%) and vescalagin (16.2%).<ref name=hydrolyzable>{{cite journal|doi=10.1002/app.30377|volume=113|issue=6|title=Polymer structure of commercial hydrolyzable tannins by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry|year=2009|journal=Journal of Applied Polymer Science|pages=3847–3859|last1=Pizzi|first1=A.}}</ref><ref name=ellagitannins>{{cite journal|doi=10.1002/app.10618|volume=85|issue=2|title=Considerations on the macromolecular structure of chestnut ellagitannins by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry|year=2002|journal=Journal of Applied Polymer Science|pages=429–437|last1=Pasch|first1=H.}}</ref><br>It has a naturally low pH value, relatively low salts content, and high acids content. This determines its astringency and its capability to fix raw hides. These properties make chestnut extract especially suitable for the tanning of heavy hides and to produce leather soles for high-quality shoes in particular. It is possible to obtain a leather with high yield in weight, which is compact, firm, flexible, and waterproof. Chestnut-tanned leathers are elastic, lightfast, resistant to traction and abrasion, and have warm color.<ref name=Wilson >Wilson, J. A. (1929)''The chemistry of leather manufacture.'' . American Chemical Society, Vol. I and II, second edition.</ref><ref name=McLaughlin >McLaughlin, G. D. and E. R. Theis (1945). ''The chemistry of leather manufacture''. American Chemical Society.</ref>
Chestnut tannin is one of the pyrogallol class of tannins (also known as [[hydrolysable tannin]]). As it tends to give a brownish tone to the [[leather]], it is most often used in combination with [[Quebracho tannin|quebracho]], [[mimosa]], [[Caesalpinia spinosa|tara]], myrabolans, and [[Valonia oak|valonia]].<ref name=palimpsest/> <br> The wood seems to reach its highest tannin content after the trees reach 30 years old. The southern European chestnut wood usually contains at least 10 to 13% more tannin than chestnut trees in northern climates.