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BOSS® 389+ weatherproofing silicone sealant is a construction-grade sealant that provides unmatched adhesion, weather resistance and can be used on a wide variety of materials. It is a one-part, neutral cure, and low-odour sealant.


  • Compatible with all structural silicone sealant.
  • Good weather and temperature resistance.
  • Medium modulus – with expansion/compression capability up to ± 25% of the original joint width.
  • Neutral cure, with a long open time.
  • Permanently elastic after curing.


  • Ideally suited for weatherproofing, waterproofing, sealing of expansion and control joints, and general-purpose glazing.
  • Other bondable surfaces include anodized aluminium, concrete, cement, wood, ceramics, and painted surfaces.
  • Works well with ACP, glass, glazed surfaces, and galvanized steel.


This product is available in clear, white, black, and grey.


Available in 290 ml cartridges and 600 ml sausages.

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