Silica in Wood

Silica content in wood is occasionally mentioned in discussions about the best type of wood to use for producing quality cutting boards, chopping blocks and countertops.

Silica is composed of the most common elements on earth, silicon (Si) and oxygen (O2). It’s also the most abundant compound in the earth’s crust, where it makes up 59% of the total composition. In many parts of the world, silica is the major constituent of sand.

There are very few species of trees that have silica content in the wood itself that may – but not necessarily – be unfavourable to cutting utensils. More than 0.5% silica in wood is harmful to cutting tools but this is usually only a problem for the equipment used during the harvesting and milling processes.

Hardwood trees from tropical areas (teak for example) tend to have a higher silica content in the wood. Silica is rarely present in more than trace amounts in the wood of temperate tree species and softwoods are generally much lower in inherent silica than hardwoods.

The highest silica levels in any tree is typically found in the bark and these higher levels commonly come from contamination through wind and during harvesting and transporting. Since tree bark is not part of a finished cutting board surface and most woods have very low silica levels, you can feel comfortable knowing that just about any wooden cutting boardchopping block or countertop will be knife friendly.

There are more important factors that determine the quality of a professional cutting board, chopping block or countertop – kiln drying, orientation of the wood grain and other characteristics of the wood itself.

Featured image taken by Dr Roger Heady. Used with permission from the Centre for Advanced Microscopy at the Australian National University and Microscopy Australia (formerly the AMMRF).