page_title: Tanning (leather)
section_title: Unhairing and scudding
hierarchical_section_title: Tanning (leather) / Beamhouse operations / Unhairing and scudding
caption_attribution_description: English: Drawing of peeling bark for the tannery in Prattsville, New York during the 1840s, when it was the largest in the world. Text below the image read "Peeling, and piling hemlock bark, for Prattsville Tannery." It was partially obscured with the top half of the letters cut off, but I think that's what it said (piling could be wrong). Français&#160;: Gravure représentant la coupe et l'écorcage d'arbres (Pruches dont l'écorce est particulièrement riche en tanins) pour en utiliser ce tain (tanin) pour la tannerie de Prattsville, dans les années 1840, quand elle a été la plus grande du monde. Le texte de la légende sous l'image est partiellement tronqué, mais il pourrait être "Ecorçage et empilage d'écorce de pruche, pour la tannerie de Prattsville"
context_page_description: Tanning is the process of treating skins and hides of animals to produce leather. A tannery is the place where the skins are processed.
  Tanning hide into leather involves a process which permanently alters the protein structure of skin, making it more durable and less susceptible to decomposition, and also possibly coloring it.
  Before tanning, the skins are dehaired, degreased, desalted and soaked in water over a period of six hours to two days. Historically this process was considered a noxious or "odoriferous trade" and relegated to the outskirts of town.
  Traditionally, tanning used tannin, an acidic chemical compound from which the tanning process draws its name. The use of a chromium (III) solution was adopted by tanners during the Industrial Revolution.
context_section_description: Unhairing agents used at this time include sodium sulfide, sodium hydroxide, sodium hydrosulfite,  calcium hydrosulfide, dimethyl amine, and sodium sulfhydrate. The majority of hair is then removed mechanically, initially with a machine and then by hand using a dull knife, a process known as scudding.
caption: Peeling hemlock bark for the tannery in Prattsville, New York, during the 1840s, when it was the largest in the world
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