Soluble oil

An oil that has had special chemicals (emulsifiers) added to allow it to form a mixture with water, called an emulsion, to produce a fluid with a mixture of their properties.

Soluble oil combines the lubricating properties of oil with the cooling ability of the water. It will not catch fire and is also relatively cheap, owing to the high water content – usually 80/90%.

It is used to cool components after tempering and gives a black, adherent oxide finish which is both attractive and corrosion-resistant.

Emulsions are liquids containing small particles of oil suspended in water which do not separate out. Normally, oil and water mixtures will rapidly separate, forming a layer of oil on the surface of the water.