page_title: Ammonia fuming
section_title: Process
hierarchical_section_title: Ammonia fuming / Process
caption_attribution_description: Unfumed European white oak. Left side is unfinished, right side is oil finished.
context_page_description: Ammonia fuming is a wood finishing process that darkens wood and brings out the grain pattern. It consists of exposing the wood to fumes from a strong aqueous solution of ammonium hydroxide which reacts with the tannins in the wood. The process works best on white oak because of the high tannin content of this wood. Fumed oak is also called smoked oak. Other species may also be fumed, but usually will not darken as much as white oak. The introduction of the process is usually associated with the American furniture maker Gustav Stickley at the beginning of the 20th century, but fuming was certainly known in Europe before this.
context_section_description: The wood to be fumed is placed in a sealed chamber with all the surfaces to be fumed exposed to freely circulating air.  A large shallow container of ammonium hydroxide solution is placed on the floor of the chamber and the chamber is sealed.  If the chamber is large or the fuming is to be done for a long time, more than one container may be provided, or the ammonia may be replenished during the process.  The fuming time depends on the amount of darkening required, the size of the chamber, and the strength of the ammonia used.  It is usual to oil the wood after fuming to fully bring out the effect.
caption: Unfumed European white oak.  Left side is unfinished, right side is oiled.
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