Tall oil is a dark yellow substance derived from the chemical pulping of pine woods. It is composed of a mixture of rosins, fatty acids, sterols, alcohols, and some other non-acid materials. The viscosity of this oily raw material can vary greatly. It can be used in its raw form or processed and used to produce numerous products such as soap, inks, and chemicals.
Chemical pulping usually involves cooking wood chips in a chemical mixture known as liquor. Doing this produces a type of soapy material that consists of rosins and fatty acids, among other things. When this process is complete, the liquor is normally black and must be separated from the pulp. This soapy material can then be mechanically separated from the black liquor. When sulfuric acid and heat are added to the material, it becomes crude tall oil.
Processing this substance can lead to the production of numerous products. There are four that are common. When the crude oil is distilled and the rosin content is above 10 percent, it is often referred to as tall oil rosin. This substance is used to make rubber, inks, and adhesives.
When the crude oil is refined and the rosin content is 10 percent and less the resulting product is known as tall oil fatty acid. This fatty acid is used in paints, cleaners, and linoleum. This type of fatty acid is often considered better than those derived from animal and vegetable oils. One advantage is that end products produced with this substance tend to have improved coloring and viscosity.
Distilled tall oil and tall oil pitch are also produced from the crude product. The distilled product is used for oil field chemicals, fuel additives, and coatings. Pitch is used as a cement emulsifier and to make products such as chemicals and biofuels.
Tall oil also has been marketed by some as an alternative fuel. There are claims that it is biodegradable and produced from renewable resources so it is better for the environment than fossil fuels. Claims have also been made that this substance can be used in conjunction with fossil fuels and biofuels or it can be used to completely replace them in fuel-burning systems.
Some pulping facilities do not sell this product. This is often regarded as an unwisely ignored revenue stream. Removing the material that makes tall oil can positively affect profits and it can also enhance machinery performance.