At its most basic an extender pigment is a naturally occurring chemical substance (usually having a white colour) that is added to a paint or coating to improve its properties such as durability, cost, and resistance to corrosion or wear.
Fillers and extenders also improve the performance and handling of the paint while being applied.
Most fillers and pigment extenders are white or colourless powders. They are generally naturally occurring minerals which are processed to remove impurities. Others are synthetic to produce a product ready for paint formulation.
Two separate extenders can often be mixed to generate a unique degree or form of pigment packing that can be modified to suit several applications. Any additional pigment introduction does not compromise the mechanical durability of the paint.
Other benefits include:
· Increased ease of paint application
· Increased adhesive properties.
· Improved film roughness
· Improved paint bulking
· Increased paint film hardness
Here is a list of the most common extenders:
Calcium Carbonate
Calcium Carbonate (whiting, chalk, drop chalk, or limestone) is a white powdery substance. It is a simple compound of the element calcium bonded to carbonate. It occurs naturally as marble and natural chalk. It is mostly made synthetic since it’s very inexpensive to precipitate a calcium chloride solution with a sodium carbonate solution.
Talc
Talc is a naturally occurring mineral composed of magnesium silicate. It is often refined to a bright white powder and is used as a thickener, lubricant, and as a filler in paint. In paint, talc adds texture and body to the paint. Also, talc is often used to make universal tints and pigment dispersions. Its unique structure can aid in the dispersion of organic pigments.
Kaolinite Calcined
Kaolin clay is a white clay that is used to make porcelain, chinaware, and even toilets. It can also be ground with organic pigments to make inexpensive paint colorants that are easier to disperse in water-based media.
Barium Sulfate
Barium sulfate, also referred by its natural mineral form barite, is a dense white powder. It is mainly used as a pigment in coatings. In oil-based paint it is nearly transparent and used as a filler and extender and to modify consistency.
Aluminum Stearate
Aluminum stearate is a white powdery compound that is a metal salt of a fatty acid. It's often referred to as an aluminum soap. Aluminum stearate is added to oil paints to stabilise the dispersion of pigments and to give the paint body as well.
For more information on extenders and advice on which is best for your requirements visit Chemgrit Coatings or contact athol@chemgritsa.co.za.
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