One part, low outgassing silicone for bonding, sealing, coating & encapsulation

Key Features

  • Meets NASA ASTM E595
  • Neutral type cure
  • Flowable consistency
  • Good bond strength to many substrates

Product Description

MasterSil 921-LO is a very special, high performance RTV silicone for bonding, sealing, coating and potting. It is a neutral curing, non-corrosive type system that passes NASA low outgassing test requirements. It is an excellent electrical insulator that spreads evenly and smoothly. The system is well suited for smaller potting and encapsulation situations. It bonds well to a wide variety of substrates, including metals, composites, ceramics, glass as well as many rubbers and plastics. Not surprisingly, it can withstand rigorous thermal cycling and shock. The lower durometer of MasterSil 921-LO facilitates its usage in conjunction with sensitive components, particularly electronic and optical ones. Similar to other single part silicones, the curing mechanism is based on humidity; the higher it is, the faster the cure. Also thinner sections cure more quickly than thicker ones. When cured in thicker sections, it is translucent. However in thinner sections, such as when bonding glass to itself, it has marvelous transparency and light transmission. Significantly, it has a wide service temperature range of -175°F to +500°F, surpassing many conventional RTVs. This versatile system can be used in aerospace, electronic, optical, specialty OEM and other types of applications, where a low outgassing, flowable silicone is required. It should be noted, in order to achieve the low outgassing properties, a seven day cure at room temperature is recommended.

Industrial Certifications

ASTM E595 Compliant

Meets EU Directive 2015/863



MasterSil 921-LO is available is various sizes and units to accommodate customer's needs.

Request Information