Extender

An extender in coating materials is an additive that is used to increase the amount of coating material without significantly affecting the basic properties such as adhesion or protection. Extenders are often used to increase the yield of a coating material, control viscosity and reduce the cost of manufacture. They are usually inorganic fillers that can affect the physical properties of the coating such as hiding power, texture and drying properties.

Commonly used extenders include substances such as talc, kaolin, calcium carbonate or silicates, which give the coating additional bulk. These fillers are relatively inexpensive and can reduce the cost of the coating by increasing the ratio of more expensive active ingredients (such as binders and pigments) to less costly extenders. Another advantage of extenders is that they can help improve the processing properties of the coating material by stabilizing viscosity or optimizing flow properties.

While extenders can improve the yield and physical properties of a coating material, they must be chosen carefully as they can affect the performance of the product in excessive quantities. In particular, they can reduce the opacity of the paint or reduce the gloss level and resistance to environmental influences. Therefore, the use of extenders in the formulation of coating materials is always adjusted so that the desired properties of the final coating are maintained.