When Tony Robinson was demonstrating the tanning process, with
the aid of a jolly, consenting lady, it was evident that this
was one of the "Worst Jobs in the World". Chemically,
something must happen to render these short term odiferous
problems permanent. Ammonia would not fill the bill but, as you
suggest, it must concern chemical/enzymatic reactions between
urine and the proteins in the cowhide, with the sulphurous
products causing the lingering smells.
Curator, Centre for Human Bioarchaeology
Museum of London
150 London Wall
London. EC2Y 5HN
Tel: +44 (0) 20 7814 5649
Fax: 020 7600 1058
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From: British archaeology discussion list
[mailto:[log in to unmask]]On Behalf Of kevin wooldridge
Sent: 27 July 2006 17:00
To: [log in to unmask]
Subject: Re: [BRITARCH] Stone-lined tanning pits ....or not!!
Regarding the odour. It seems to have something to do with the clay lining of the tanning pit which often exhibits as a yellowish or white substance on the inside of the pit darkening to normal London Clay brown/grey/blue on the outer side.
My own guess ('O' level Chemistry only I'm afraid) is that the yellowing of the clay is caused by the presence of selenite (Calcium Sulphate) in the London Clay and perhaps other sulpharous compounds leaching from the 'tanning formula' and somehow being 'fixed' through contact with the clay. Does that sound feasible and could that account for the longevity of the odour?