Talc is used in paint to improve its physical properties, which include wet scrub resistance, optical properties, weathering protection and more.
Floated Finntalc from Mondo Minerals does not vary in colour, and its tight L,a,b-window is strictly monitored. It thus ensures that the selected paint colour can be accurately reproduced, making it the best choice for highly demanding applications like tinting systems.
The property that most greatly influences the durability of decorative interior paints is their wet scrub resistance. Our pure, hydrophobic talc improves this property considerably. The weather re-sistance of outdoor paints is also improved. Using the right talc is extremely important here. For example, talc that contains chlorite (Mg-Al sili-cate) is not hydrophobic. Simply choosing the right product can make the difference between a paint that meets the criteria for wet scrub resistance class 1 (according to ISO 11998) and class 2. Your optimum choice here is Finntalc with its particularly hydrophobic, macrocrystalline structure.
When a paint film forms, tension can cause cracks in the dispersion paint. This can vary greatly. It can only be prevented completely by using a reinforcing extender. Pure and platy talc particles act as bridges between the binder agglomerates to strengthen the paint film. The greater the aspect ratio and the particle size of the talc, the better the crack resistance. Pure, macrocrystalline Finntalc M20SL with its laminar structure is ideal, because it effectively reduces shrinkage of binders during drying.
Macrocrystalline Finntalc has a viscosity profile that is in great demand for decorative paints. Talc increases the pseudoplasticity and reduces sagging and splattering. Settling is also reduced, extending the shelf life of the paint.
Talc platelets reduce the permeability to oxygen and water and protect the binder against UV radia-tion. This improves the weather resistance of outdoor paints.
The optical properties – hiding power, whiteness and gloss – are extremely important, particularly for decorative paints.
Talc gives paints and coatings a satiny look. In particular, dispersion paints for indoor areas should have as little gloss as possible. Because the glossier they are, the more noticeable irregularities such as brush strokes become.
For paints and coatings with sub-critical pigment-volume concentrations (i.e. in which the pigments are completely covered by the binder), fine talc reduces gloss just by absorbing excess binder through its large surface area.
Paints with high pigment-volume concentrations, on the other hand, are efficiently matted using coarse, laminar-structured talc particles. The matting efficiency of talc can be increased by selecting a narrow spectrum of coarse talc plates. 3 - 5% of a coarse, double air classified, de-dusted talc (Finntalc M40) can be sufficient to achieve a dead matt interior paint.
Finding the right balance of properties is a great challenge, as opacity and whiteness also work against each other. The darker the paint film, the higher the opacity, and vice versa.
Paints that contain Finntalc M20SL, for instance, demonstrate an excellent combination of optical properties, such as optimum balance opacity and whiteness at low gloss values.
Also, very fine talc with a laminar structure (high aspect ratio) helps to distribute titanium oxide (spacing effect). This improves coverage while reducing formulation costs.