Red rot

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Red rot (also redrot) is a degradation process found in vegetable-tanned leather.^[1]

Red rot is also a term used to describe a late stage of wood decomposition. Red rot is composed of small chunks of decomposing wood (usually from a fallen tree) which have turned red in colour, and later break down to a fine red mush that will clump together if squeezed.

Red rot is also a term commonly used to refer to any reddish patch of corrosion on a copper-based alloy, such as brass. However, this loose usage covers two distinct but related conditions, surface corrosion and deterioration of the alloy due to de-zincification.

[edit] Causes of red rot

Red rot (for leather) is caused by prolonged storage or exposure to high relative humidity, environmental pollution, and high temperature. In particular, red rot occurs at pH values of 4.2 to 4.5. Sulfur dioxide converts to sulfuric acid which forms hydrogen peroxide. The peroxide combines with residual tannins in the leather to oxidize proteins, creating ammonium sulfate and ammonium bisulfate^[2]

Red rot (in brass musical instruments^[3]) is from the loss of the zinc alloyed with the copper. It results from the chemical reaction of acidic compounds left from the breath of the musician. Carbon Dioxide is a natural part of our breath and when it comes in contact with water it forms carbonic acid. Drinking carbonated beverages such as sodas can increase the level of the acid inside the instrument. Also some metal cleaning compounds have acid in them and can attack the zinc in the brass. Also, moisture left inside the instrument can encourage the growth of bacteria that produce acids. The effect can be minor and only cosmetic or it can become severe enough that the metal actually leaks air through sponge like holes. Eventually the copper becomes so soft that it can be crushed with very little effort. Cleaning the instrument after each use can usually keep red rot from ever affecting the instrument. ^[4]

[edit] Effects on leather

The disease manifests as a characteristic powdering of the leather's surface, along with structural weakness through loss, delamination, and a felt-like consistency. The damage caused by red rot is irreversible.

[edit] References

1. ^ Applebaum, Barabara. Guide to Environmental Protection of Collections p. 185. Sound View Press, 1991
2. ^ Stambolov, Todor. Environmental influences on the weathering of leather. From International leather and parchment symposium, vol 8. May 1989. Deutsches Ledermuseum/Deutsches Schuhmuseum (1989), pp. 1-5, [English + German]
3. ^ http://en.wikipedia.org/wiki/Brass_instruments
4. ^ About Red Rot