Dow Corning® 817 High Modulus Adhesive

High modulus neutral silicone sealant


  • Non-corrosive, odorless, ready to use gun grade sealant which reacts with air moisture
  • Excellent unprimed adhesion on most glasses, metals and mirror coatings
  • Outstanding resistance to heat and humidity
  • Resistant to ozone, ultra-violet radiation and temperature extremes 

High modulus neutral silicone sealant


Dow Corning® 817 High Modulus Adhesive is a one-part silicone sealant for internal fixation of mirrors, coated glass or metal panels onto various substrates and for bonding of glass and back plate in solar thermal panels


Specification Writers: These values are not intended for use in preparing specifications. Please contact your local Dow Corning sales office or your Global Dow Corning Connection before writing specifications on this product.

Test method*



Property Unit

Cure system
Application temperature °C



Service temperature range °C
°F -58 to +212

Working time minutes
Specific gravity g/ml
Slump mm
12*12*50mm size T.A. joint (ISO 8339)
Hardness (Shore A) 38 Y oung modulus MPa 1.2

* CTM: Corporate Test Method, copies of CTMs are available on request.

Surface preparation
Ensure that surfaces to be sealed are clean, dry, sound and free from grease, dust and other contaminants which could impair adhesion. Surfaces can be cleaned and degreased by wiping with a suitable solvent such as
Dow Corning® R40 Universal Cleaner on a clean oil and lint-free cloth before application of sealant. Check to ensure that the mirror has been evenly coated, is protected by lacquer and is free of scratches.

Note: When using any solvent, always provide adequate ventilation. Avoid heat, sparks and open flames. Use solvent resistant gloves. Observe and follow all precautions listed on solvent container label.


For specific advice, please refer to the Dow Corning® Primers’ Guide or contact one of Dow Corning’s Regional Service Centers for technical assistance.

Sealant application

The sealant is ready to use. Apply 10mm wide strips vertically on the back of the mirror in 100mm intervals. Then press the mirror onto the surface, preserving a constant bead thickness of 2mm for optimum cure and mechanical grab. Support the mirror for a minimum of 24 hours using adhesive tapes. This will ensure good contact and a minimum of displacement. Air should be allowed to circulate freely around the edges of the mirror thereby allowing the sealant to cure.