American Polywater® FST™ Foam Duct Sealant

Protect Your Cable Runs with Closed-Cell Foam

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What's special about this foam duct sealant?

  • Made to keep water, sewer gases, and rodents out of conduit for safe cable runs
  • Compatible with all types of cables and conduit, great application flexibility
  • Designed for harsh environments and permanent or semi-permanent applications
  • Holds 15 ft water-head pressure for an extended period of time while keeping your cables safe
  • Click for More Features
Made in USA

Running cable run in a hostile environment is no easy task. Sometimes conduit, no matter how rigid, is simply not enough protection for your cables. Water, gas, and even rodents can get into the conduit and damage your wires if the conduit is not properly sealed. FST Foam Duct Sealant plays a key role in such applications by completely sealing conduit, equipping it to handle events that most open-cell canned foams can't protect against.


AP-FST-250 FST Duct Sealant 8.5 oz Caulking Tube Style 
AP-FST-250KIT1 FST Duct Sealant 8.5 oz Caulking Tube Style - KIT
AP-FST-DAM 24" Foam Damming Strip
AP-HP-P158ID Conduit Pre-Treating Cleaning Wipe
  • Great adhesion to metals, plastics and, PVC, for a firm grip and tight seal
  • Easy to remove in case the need for a new cable run arises
  • 8.5 oz tube works with a regular caulking gun for easy application
  • Foam tolerates cable movement, allowing for removals if necessary
  • Quickly expands and cures even in the presence of water, reducing application time
  • Once cured, foam is strong, resilient and chemically resistant
  • Made in the USA USA


FST-250KIT1 includes:

  • (1) 8.5-oz Two-Part Foam Sealant, caulking tube style (FST-250)
  • (4) 24" Foam Damming Strips (FST-DAM)
  • 3 Mixing Nozzles
  • 1 Pair Disposable Gloves
  • 1 Positioning Rod for foam dam
  • 1 Pre-Treating Wipe (HP-P158ID)
  • 1 Resealing Cap
  • 1 Instruction Sheet


Foam Duct Sealant Specifications (PDF) PDF


Cured Properties
Appearance Light yellow color with small, even cells
Closed Cell Percentage 98%
Density 6 lbs/cubic ft.
Compressive Strength (ASTM D1691) 330 psi
Tensile Strength (ASTM 1623) 270 psi
Flexural Strength (ASTM D790) 460 psi
Seal Strength Water 40 feet intermittent - 15 feet continuous
Seal Strength Air >5 psi


CURE RATE - Reaction Time (minutes)

MATERIAL 40° F (4° C)  70° F (21° C)
Foaming, Expansion Complete 8 - 9 minutes 4 - 5 minutes
Hard, Non-Sticky Skin Formation 15 - 18 minutes 7 - 9 minutes






Cable Removal AidAmerican Polywater™ CableFree™ Cable Removal Aid
CableFree™ is designed to help you with the process of removing cables from conduit. Time and insufficient maintenance can create adhesive agents around your cable run and all around the inside of the conduit, making it difficult to remove wires without damaging them or being forced to cut the conduit.

Cable LubricantPolywater SPY Cable Lubricant
Offers excellent cling and continues to work even after it has dried, because the residue of the spray is a thin, slippery film that retains lubricity for many months. Ideal to use in industrial electrical, communications, construction and maintenance projects.


Conduit AdhesiveBonDuit™ Conduit Adhesive
Bonduit® conduit glue keeps your conduit fittings securely attached while creating a complete seal. The easy to apply formula goes on in just seconds, and sets in minutes to save installation time and overall labor costs.

Fish TapeIDEAL Tuff-Grip™ Steel Fish Tape
Manufactured from carbon-blued steel. The 1/8" wide tape has a tensile strength of 2100 lbs and the 1/4" has 4200 lbs of tensile strength.

Q:Polywater FST 250

I have three 3" pipes to seal with cables. Will one FST-250Kit1 be sufficient? Do I also need the Tool-250 or do I use a caulking gun?

Asked by Anonymous user on


  • - Thank you for your question. One kit should be enough and yes you can use a regular caulking gun.

    Fernando M. on

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