WACKER® RTV-S 691 A/B is a self levelling, two-part addition curing silicone rubber which can be vulcanised at room temperature. Due to its low outgassing rate and low temperature flexibility it is recommended especially for space applications.

It has been designed and is used as adhesive for solar cells on solar generators for space applications such as satellites.


  • resistant to low temperatures
  • glass transition temperature: < -100 °C / -148 °F
  • particularly low volatile contents
  • admitted for aerospace applications by ESTEC (European Space Research and technology Centre) according to specification ECSS-Q-70-02A (corresponds to former ESA PSS-01-701)

Specific features of WACKER® RTV-S 691 A/B

  • Heat resistant
  • Low volatile
  • Low-temperature flexible
  • UV stable

Mixing ratio is 9:1 p.b.w Before taking component A out of the container or adding the catalyst, stir the material thoroughly. Components A and B can be mixed by hand or with metering equipment. The material must be evacuated before application to remove enclosed the bubbles. For detailed information refer to our leaflet "Wacker RTV-2 Silicone Rubber Processing". Important: The platinum catalyst is contained in component A. Caution! Only components A and B that have the same lot numer may be processed together! Mixing of the components It is ablolutely imperative that any equipment, such as mixing vessels, spatulas and stirres, that is used to process Component A (which contains the platinum catalyst) or the mixture of both components does not come into contact with Component B (which contains the crosslinker). Therefore, all equipment should be clearly labeled.

WACKER® RTV-S 691 A/B is used as silicone adhesive with minimum outgassing behaviour for space projects, e. g. bonding for solar cells in satellites.

RTV-S691 can be applied by silk screen printing or by dispensing equipment. In order to make the rubber adhere to other materials (e. g. glass, aluminium, silver, epoxy resin, polyester resin), it is necessary to pretreat the surface with Primer G 790.


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.

Sales and support

Wacker Chemical Corporation
3301 Sutton Road
Adrian, MI 49221-9397
United States
+1  888  922-5374 (Phone)

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