SILRES? BS 290 is a solventless silicone concentrate  that is based on a mixture of silane and siloxane.  SILRES? BS 290 is dilutable with organic solvents. Dilute solutions of SILRES? BS 290 in organic  solvents serve as high-quality general-purpose water  repellents for impregnating and priming mineral and  highly alkaline substrates. Special features - good depth of penetration - high resistance to alkalis - tack-free drying - effective even on damp substrates - rapid development of water repellency After application to the mineral substrate, SILRES? BS  290 reacts with the atmospheric moisture or pore water  in the substrate, thereby generating the active  ingredient while liberating alcohol. The active  ingredient greatly lowers the water absorbency of the  substrate, which nevertheless retains a very high  degree of water vapour permeability since neither  pores nor capillaries are clogged. Application SILRES? BS 290 is suitable for imparting water  repellency to absorbent, porous, mineral construction  materials, e. g.: - brickwork - all kinds of concrete - aerated concrete - sand-lime brickwork - cement fiberboards - mineral plasters - mineral-based natural and artificial stone - mineral paints SILRES? BS 290 is also suitable as primer for exterior  paints. SILRES? BS 290 is not suitable for rendering gypsum  water repellent. Processing Flooding, preferably not under pressure, is the best  technique for applying SILRES? BS 290, which is  ready to use after dilution. Apply several coats, wet on  wet, until the substrate is saturated. Generally, at least  two applications suffice for all substrates. Do not leave long breaks between coats. Apply the  next when the substrate has absorbed the previous  one and is no longershiny (wet-on-wet working). The  substrate must not have damp spots, i. e., it should  look dry. The requisite quantity of SILRES? BS 290  depends on the adsorbency of the substrate. The  amount of impregnating agent required for a substrate  and the effectiveness of the impregnation should be  determined on site by testing a small area of the  material to be treated. Dilution The solvents best suited for diluting SILRES? BS 290  are aliphatic hydrocarbons (e. g. White Spirit 130/175),  aromatic hydrocarbons (solvent naphtha, e. g. Shellsol  A) or low-odor isoparaffin hydrocarbons (e. g. Isopar  H). The solvent used should have a boiling range of  140-190°C and an evaporation number of 30-90. If the above-mentioned hydrocarbon solvents are  used, SILRES? BS 290 should be diluted in a weight  ratio of 1:11 to 1:15. Anhydrous alcohols, such as  ethanol or 2-propanol, could also be used and are  even indispensable whenever contact of the  impregnating agent with solvent-sensitive materials  (such as expanded polystyrene, bitumen, etc.) cannot  be avoided. The alcohol must be completely  anhydrous. If alcohol is used as a solvent, a dilution  ratio of 1:12pbw is recommended. When impregnating  slightly damp substrates, SILRES? BS 290 will give  better results if diluted with hydrocarbons than with  alcohol. Stir vigorously when adding the diluent to SILRES? BS  290. Since SILRES? BS 290 reacts with humidity,  prolonged contact with air must be avoided. The  containers must be hermetically sealed. Before applying SILRES? BS 290, be sure to cover  

windows and other non-absorbent surfaces properly

because the product cures so quickly that it will be

extremely difficult, if not impossible, to remove after a

few hours. Wipe off any splashes on window panes

immediately, using a solvent if necessary.

For this reason, the figures quoted below are intended

as a guide only:

Storage

The 'Best use before end' date of each batch is shown

on the product label.

Storage beyond the date specified on the label does

not necessarily mean that the product is no longer

usable. In this case however, the properties required

for the intended use must be checked for quality

assurance reasons.

Safety notes

Comprehensive instructions are given in the

corresponding Material Safety Data Sheets. They are

available on request from WACKER subsidiaries or

may be printed via WACKER web site

http://www.wacker.com.