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Product Description

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SI 388 is a one-part, moisture- curing RTV (room temperature vulcanizing) silicone sealant/adhesive that is non-slump and cures to form a tough, permanently flexible rubber. The non-corrosive curing system of ASI 388 makes it ideally suited for protecting, sealing and insulating corrosion-sensitive electronic and electrical materials such as copper, brass, silver, etc. ASI 388 has been specifically formulated for use in electrical/electronic production and assembly because it:

  • has good dielectric properties
  • has high surface resistivity
  • resists electrical tracking
  • repels water to protect electrical properties

ASI 388 is a neutral-cure silicone that emits no objectionable odors during cure and is ideally suited for use in confined areas. However, adequate ventilation should be provided when ASI 388 is used in large-scale production. ASI 388 is a 100% silicone and has excellent resistance to:

  • ozone
  • UV
  • airborne chemicals
  • temperature changes from -57 C to   +204°C (-70°F to +400°F)


ASI 388 is an excellent sealant/adhesive for many electrical and electronic applications where corrosion to metals, particularly copper, brass, silver, etc., is a problem. Such applications include:

  • lead-wire entries
  • conduit terminal boxes
  • component mounting
  • electrical connections
  • conduit ends
  • splices
  • cover plates
  • coaxial cable connectors
  • printed circuit boards
  • conductor entry holes


All surfaces should be clean and dry. It is recommended that bonding surfaces be solvent wiped with oil-free solvents, such as xylol, toluol naphtha or non-flammable chlorinated solvents. Do not wipe with oil-based solvents such as Varsol. Allow surface to dry thoroughly before applying sealant.


ASI 388 is ready to use and requires no mixing or additives. The cure mechanism begins as soon as the sealant comes in contact with the air. At conditions of 25 C (77° F) and 50% relative humidity, the sealant will skin in 15 minutes and fully cure within 48 hours (1/8 bead). Higher humidity accelerates cure. Tooling should be done before skinning takes place. In applications where partial total confinement of sealant is prevalent, the time required for proper cure is lengthened by the degree of confinement.


Priming of ASI 388 is normally not required for application to most substrates. Unprimed adhesion can be readily tested by applying a small trial bead and allowing 7 days for maximum adhesion to occur. If primer is required, contact ASl for technical assistance.


ASI 388 is available in clear and white. Special colors are available upon request. Call for price and availability.


ASI 388 meets the requirements of MIL 46l06 Type 1.


ASI 388 is permitted under regulations of the Food and Drug Administration where incidental food contact might be involved. FDA Regulation number is 177.2600.

To view MSDS and Product Data sheet please visit www.americansealantsinc.com

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Product Reviews

  1. Does what is suppose to. 5 Star Review

    Posted by on 21st Sep 2017

    The silicone is use on electronic rectifiers, bare copper, it adheres properly and no corrosion signs any where. It does what suppose to... isolate, support and protect the electronic connection where is being use.

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