Some liquid adhesives are strong, but thin (low viscosity). When adhesives are thin, they quickly soak into porous papers, reducing efficiency. Adding sodium bentonite or hectorite instantly creates a thickened adhesive that sits on top of porous paper -- the penetration is controlled. Bentonite or hectorite is usually blended directly with a liquid adhesive. Improved gelling is accomplished by premixing these clays with a little fresh water, then adding the clay premix to the adhesive until the right balance of properties is reached.
A small quantity of sodium bentonite, specifically SPV-200, added to each sack of cement increases the plasticity and improves the handling of the mixture, without reducing the set strength. As the amount of clay per sack is increased (up to 20%) more water is required for the cement mixture, making a “fat” mixture for filling large voids. In plasters, bentonite can add significantly to the adhesion properties of the base mix.
Both powdered and granular sodium bentonites are used in the production of common and face brick. As a bonding agent, bentonite assists in the elimination of chipping and deformation. Suitable industrial bentonites also add plasticity, thus reducing the moisture in the formulation. The increased plasticity results in longer die life, and reduces power requirements on the extrusion equipment.
Sodium bentonite powder is an active carrier in the formulation of dust insecticides and biocides. It clings to the plant and is held in place by traces of moisture on the plant, thus reducing loss of toxicant due to blowing and dusting. Sodium bentonites, such as SPV-200, impregnate easily with biocides dissolved in an organic solvent. This toxicant solution is sprayed on SPV-200 and tumbled until the solvent has essentially evaporated. This leaves a film of toxicant impregnated in and on the SPV-200 products.
Small amounts of hectorite and magnesium aluminium silicate added to the suspension type of polishes and liquids, or 5% to 10% for the paste type of polish, keeps the product in uniform suspension over long periods. These clays increase the consistency, makes spreading and removal easier.
Hectorite and sodium bentonites are used in welding rod coatings. Used primarily as a binder to adhere the various fluxing materials to the welding rod, it also acts as a suspending agent in the coating solution.
Linings are used in furnaces to prevent molten metals from destroying them. In general, linings consist of ganisters, silica stone, quartz pebbles, or refractory grog. Most of the linings consist of graded sizes of ganisters in which the voids between large grains are filled with progressively smaller grains creating a firm, yet brittle body. Increasing the plasticity of linings enhances durability and performance. This can be accomplished by adding sodium bentonites, and, for greater performance, adding hectorites.
Bentonites and hectorites are also used as a binder in high temperature furnace cements, mortars, and furnace gun mixtures to provide higher stickiness, reduce cracking at high temperatures, and supply more coverage per volume of cement, qualities not found in other clays.
Small quantities of air-classified bentonite or hectorite impart stabilization of aerosols and cleaning compounds due to the large surface area of bentonites, and even greater surface area of hectorites. Both hectorite and bentonite are compatible with organic gums and associative thickeners, modify the consistency and feel of organic thickeners by reducing tackiness, gumminess and stringiness.
A small amount of sodium bentonite, such as SPV-200, has excellent capacity for thickening latex, producing mixtures which are quite stable, have less coherence and more adherence, and are more readily vulcanizable. With careful handling, dry bentonite can be dispersed directly into pure latex.
In the manufacture of graphite pencils, air-classified grades of sodium bentonite and micronized hectorite are regularly used to bind the graphite compound in pencil lead.