Manufacturers treat wood for use in construction. There are many different ways they treat wood timbers based on their purposes. The treatment may be to make them weatherproof, insect proof or saltwater proof. Copper-based treatments are popular because of their low costs and more harmless side effects compared to other synthetic treatment options.
Copper sulfate solutions for wood treatment consist of a stable copper compound mixed with a soluble liquid. The goal is allow the copper to penetrate deep into the wood fibers and stay there. Copper oxides, copper sulfates, copper hydroxide, copper carbonate and many other compounds are used, sometimes in combination. The manufacturer soaks the wood in these solutions for an extended period of time.
Copper is a natural fungicide: in other words, it makes it very difficult for fungus and mold to grow on the wood. If any spores try to grow, they are poisoned by the copper elements and die. This makes copper treatment common for timbers that are meant to be used outdoors. Boards hidden by siding are rarely treated with copper solutions, since they will be insulated, but those used to make columns or decks often undergo such treatments.
Copper is toxic to mold and fungi, but is naturally harmless to most mammals, except in very high doses. This makes it very environmentally safe compared to the other options. This also makes the regulation of copper treatments easier and makes copper solutions much more affordable. Some organizations actively advocate replacing other types of wood treatment with the copper method.
Copper sulfate treatments, while effective at penetrating wood and protecting against mold and, to some extent, weather wear, are not the most efficient protective solutions available. Wood timbers used in saltwater must typically be fully coated in a copper sheath to repel the corrosive water, while other treatments exist that offer better protection and longevity at a higher price. Wood treated with copper also takes longer to decompose than other wood.
In addition to the many copper solution treatments, other minerals and ion treatments are available to treat wood. However, the most popular treatment remains petroleum-based oils and solvents that seep into the wood and replace the water there. These treatments, while the least healthy for the environment, provide necessary protection against saltwater and harsh weather conditions.