Editing Tannin (section)

=== Other methods ===
The hide-powder method is used in tannin analysis for [[leather]] tannin and the Stiasny method for [[wood adhesive]]s.<ref>"Tannin analysis of Acacia mearnsii bark – a comparison of the hide-powder and Stiasny methods". Zheng G.C., Lin Y.L. and Yazaki Y., ''ACIAR Proceedings Series'', 1991, No. 35, pp. 128–131 ([http://www.cabdirect.org/abstracts/19920657723.html;jsessionid=F49F74287B59E2847142A9BFED7349DC abstract] {{webarchive|url=https://web.archive.org/web/20140709035011/http://www.cabdirect.org/abstracts/19920657723.html;jsessionid=F49F74287B59E2847142A9BFED7349DC |date=9 July 2014 }})</ref><ref>Study on Fast Determination Content of Condensed Tannin Using Stiasny Method. Chen Xiangming, Chen Heru and Li Weibin, Guangdong Chemical Industry, 2006–07 ([http://en.cnki.com.cn/Article_en/CJFDTOTAL-GDHG200607012.htm abstract] {{webarchive|url=https://web.archive.org/web/20150402162931/http://en.cnki.com.cn/Article_en/CJFDTOTAL-GDHG200607012.htm |date=2 April 2015 }})</ref> Statistical analysis reveals that there is no significant relationship between the results from the hide-powder and the Stiasny methods.<ref>{{cite journal | last1 = Guangcheng | first1 = Zheng | last2 = Yunlu | first2 = Lin | last3 = Yazaki | first3 = Y. | year = 1991 | title = Bark tannin contents of Acacia mearnsii provenances and the relationship between the hide-powder and the Stiasny methods of estimation | journal = Australian Forestry | volume = 54 | issue = 4| pages = 209–211 | doi = 10.1080/00049158.1991.10674579 | bibcode = 1991AuFor..54..209G }}</ref><ref>''Leather Chemists' Pocket-Book: A Short Compendium of Analytical Methods''. [[Henry Richardson Procter]], Edmund Stiasny and Harold Brumwel, E. & F.N. Spon, Limited, 1912–223 pages ([https://archive.org/details/leatherchemists00brumgoog book at Internet Archive] {{webarchive|url=https://web.archive.org/web/20161216075444/https://books.google.com/books?id=BrtJAAAAIAAJ&oe=UTF-8 |date=16 December 2016 }})</ref>

;Hide-powder method
400&nbsp;mg of sample tannins are dissolved in 100&nbsp;ml of distilled water. 3&nbsp;g of slightly chromated hide-powder previously dried in vacuum for 24h over CaCl<sub>2</sub> are added and the mixture stirred for 1 h at ambient temperature. The suspension is filtered without vacuum through a sintered glass filter. The weight gain of the hide-powder expressed as a percentage of the weight of the starting material is equated to the percentage of tannin in the sample.

;Stiasny's method
100&nbsp;mg of sample tannins are dissolved in 10&nbsp;ml distilled water. 1&nbsp;ml of 10M HCl and 2&nbsp;ml of 37% [[formaldehyde]] are added and the mixture heated under reflux for 30 min. The reaction mixture is filtered while hot through a sintered glass filter. The precipitate is washed with hot water (5× 10&nbsp;ml) and dried over CaCl<sub>2</sub>. The yield of tannin is expressed as a percentage of the weight of the starting material.