Grease is made from a liquid lubricant with what added to it to make it semi-solid?

Grease is primarily characterized as a semi-solid lubricant, and its consistency is achieved by the addition of thickeners to a liquid lubricant, such as mineral oil. Thickeners are typically made from various materials, including soaps or other polymeric substances, which increase the viscosity of the liquid, transforming it into a semi-solid state. This semi-solid nature allows grease to adhere better to surfaces and provides effective lubrication over a wider range of temperatures and conditions compared to liquid lubricants alone.

While other substances like oils, solvents, and emulsifiers play significant roles in lubrication and compound formulations, they do not serve the primary function of converting a liquid lubricant into a semi-solid form. Oils are the base for grease, solvents are often used for dilution or cleaning, and emulsifiers help stabilize mixtures but are not responsible for achieving the thick consistency that defines grease.