VOC-Free Additive makes gypsum dry-mix mortar water repellent.

Press Release Summary:

Used to render gypsum-based dry-mix mortars hydrophobic, SILRES® BS POWDER S consists of methyl siliconate produced as colorless, free-flowing powder. Water repellency develops as soon as construction material has set, and gypsum dry-mix mortars formulated with this agent can be mixed with water quickly and without generating any dust. Requiring 0.2% by weight for effective use, product can be used with all types of gypsum, irrespective of pH, and in indoor environments.

Original Press Release:

WACKER Develops Highly Efficient Water-Repellent Agent for Gypsum Dry-Mix Mortars

Munich – Munich-based chemical Group WACKER has developed a novel additive for rendering gypsum-based drymix mortars hydrophobic, i.e. water-repellent. Sold under the name SILRES® BS POWDER S, the powder is highly efficient and free of volatile organic compounds. The water repellency develops as soon as the construction material has set.

Furthermore, gypsum dry-mix mortars formulated with SILRES® BS POWDER S can be mixed with water very quickly without generating any dust.

Moisture can do irreparable damage to gypsum building materials. To prevent this and to protect the set gypsum mortar against moisture, powder-form water-repellent agents are admixed with the dry-mix mortar. This requires the use of carrier or encapsulation materials as a way of converting the conventional liquid active ingredients into a powder. These auxiliary materials delay the onset of the hydrophobic effect of the liquid water-repellent until the gypsum mortar has been mixed with water and has set. However, conventional powder-form water repellent agents have the disadvantage that they are composed almost entirely of carrier material. The actual active ingredient makes up only a few percent of the total weight. This is not very efficient from the perspective of both weight and costs.

The solution here is to use SILRES® BS POWDER S. The new additive for dry-mix mortars does not require any auxiliary materials, consists entirely of a novel active ingredient in powder form and, as such, is extraordinarily efficient. Just 0.2 weight percent of SILRES® BS POWDER S is enough to render gypsum construction materials water-repellent. Gypsum containing the new additive absorbs as much as 90 percent less water when set and so can be employed in bathrooms, kitchens, stairwells and garages. Gypsum-based wall plasters, joint fillers, top-coat materials, floor screeds, and adhesives that have been formulated with SILRES® BS POWDER S are thus suitable for use throughout house interiors.

SILRES® BS POWDER S consists of a methyl siliconate which is produced as a colorless, free-flowing powder by a special process. The active ingredient is inherently soluble in water, a property which confers excellent mixing properties when the mortar is being prepared. Nonetheless, the gypsum mortar turns water-repellent as soon as it sets. SILRES® BS POWDER S can be used with all types of gypsum, irrespective of the pH. It eliminates the pre-reaction times which are often needed by conventional powder-form water-repellent agents. Moreover, it can be used indoors, since it is environmentally friendly and releases neither alcohol nor volatile organic compounds (VOCs).

About SILRES® Masonry Protection Products

WACKER sells numerous silicone-based masonry protection agents under the name SILRES® BS. The raw materials and active ingredients are based on water-repellent silanes, silicone fluids, silicone resins and aqueous silicone emulsions. All products are primarily designed to make construction materials water-repellent, as a way of protecting them from moisture and thus from long-term damage.

Silicones form a strong bond to mineral surfaces, where they build up an extremely stable, long-lasting silicone network that is waterrepellent, yet still permeable to water vapor. Silicones protect numerous mineral construction materials, ranging from facades, masonry, terracotta bricks and roof tiles, to thermal insulation materials, concrete, and gypsum products. Modern silicone resin emulsion paints also utilize the hydrophobic or water-repellent properties of silicone resins.

For further information, please contact:

Wacker Chemie AG

Media Relations and Information

Florian Degenhart

Tel. +49 89 6279-1601

Fax +49 89 6279-2877


The company in brief:

WACKER is a globally active chemical company with some 16,300 employees and annual sales of around Euros4.63 billion (2012). WACKER has a global network of 24 production sites, 22 technical competence centers and 53 sales offices. WACKER SILICONES Silicone fluids, emulsions, rubber and resins; silanes; pyrogenic silicas; thermoplastic silicone elastomers WACKER POLYMERS Polyvinyl acetate and vinyl acetate copolymers in the form of dispersible polymer powders, dispersions, solid resins and solutions used as binders for construction chemicals, paints and coatings, adhesives, plasters, textiles and nonwovens, as well as for polymeric materials based on renewable resources WACKER BIOSOLUTIONS Biotech products such as cyclodextrins, cysteine and biologics, as well as fine chemicals and PVAc solid resins WACKER POLYSILICON Polysilicon for the semiconductor and photovoltaics industries Siltronic Hyperpure silicon wafers and monocrystals for semiconductor components

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