DOWSIL 3-6548

Harmonization Code : 38159000 | Unspecified reaction initiators, accelerators, and catalytic preparations

DOWSIL 3-6548

Main features

  • Fire-Resistant RTV Silicone Foam
  • 2x to 4x Liquid-Volume Expansion
  • Flexible Medium-Density Ozone/UV-Resistant Foam

Product Description

DOWSIL™ 3-6548 RTV Foam Kit is a two-part, room-temperature-vulcanizing silicone foam primarily used in fire-resistant penetration-seal and linear-joint systems. It expands to approximately two to four times its liquid volume and cures into a flexible, medium-density elastomeric foam, allowing it to fill irregular openings and difficult-to-reach spaces. The product is formulated to withstand high temperatures and confine smoke, flames, and gases in supported building-system configurations. Its expanding, electrically insulating silicone foam structure also supports use in electronics applications where flexible filling, cushioning, insulation, or environmental protection is required. Part A and Part B are mixed at a 1:1 ratio by weight or volume.

Key features

  • Fire-resistant sealing: Primarily positioned for specified penetration-seal and linear-joint systems that restrict the passage of smoke, flames, and gases.
  • Expanding RTV foam: Expands to approximately two to four times its liquid volume and cures at room temperature to fill complex or difficult-to-access spaces.
  • Flexible insulating foam: Forms a medium-density silicone foam with approximately 50% closed cells and documented dielectric properties for building and electronics applications.

Applications / Suitable for

  • Fire-resistant penetration-seal systems
  • Linear floor and floor-to-wall joints
  • Sealing irregular openings against smoke, flames, gases, and contaminants
  • Electronics applications requiring flexible filling, cushioning, insulation, or environmental protection
Product Family

DOWSIL 3-6548

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TDS, SDS & Technical Documents

Technical Specifications

General Properties
Compression Pressure
0.71 Kg/cm2
Density
Volumetric mass per unit
300 kg/m3
Thermal Properties
Thermal Conductivity
Thermal conductivity describes the ability of a material to conduct heat. It is required by power packages in order to dissipate heat and maintain stable electrical performance. Thermal conductivity units are [W/(m K)] in the SI system and [Btu/(hr ft °F)] in the Imperial system.
0.075 W/m.K
Electrical Properties
Dielectric Strength
Dielectric strength is measured in kV per mm and is calculated by the Breakdown voltage divided by the thickness of the tested material. Those two properties go hand in hand and while Breakdown voltage is always thickness dependent, dielectric strength is a general material property. As an example, the dielectric strength of Polyimide is 236 kV/mm. If we place 1mm of Polyimide between two electrodes, it will act as an insulator until the voltage between the electrodes reaches 236 kV. At this point it will start acting as a good conductor, causing sparks, potential punctures and current flow.
6.6 kV/mm
Volume Resistivity
Volume resistivity, also called volume resistance, bulk resistance or bulk resistivity is a thickness dependent measurement of the resistivity of a material perpendicular to the plane of the surface.
2.25E15 Ohms⋅cm

Additional Information

Technical properties

As-supplied / before-processing properties

Typical values for the separate liquid components and properly mixed material. These values are not intended for preparing specifications.

Property Value Unit Method / condition
Appearance — Part A Black liquid — CTM 0176
Appearance — Part B Off-white liquid — CTM 0176
Specific gravity — Parts A and B 1.05–1.11 — CTM 0097; 25°C (77°F)
Viscosity — Part A 40–60 poise CTM 0050; Brookfield HAF, spindle No. 3 at 10 rpm
Viscosity — Part B 50–75 poise CTM 0050; Brookfield HAF, spindle No. 3 at 10 rpm
Mix ratio 1:1 — Part A to Part B, by weight or volume
Snap time / working time 1–2 minutes Properly mixed material at 25°C (77°F); time to non-pour condition and beginning of foam rise

After-processing / final-state properties

Typical properties after mixing one part A with one part B and curing at 25°C (77°F) for 24 hours, unless otherwise stated. Results may vary with cured foam density.

Property Value Unit Method / condition
Appearance Dark gray-black elastomeric foam — CTM 0176
Free-foam density 0.22–0.32 g/cm³ CTM 0812; power mixed for 30 seconds and cured unconfined
Closed-cell content 50 % CTM 0826; breathability method
Tensile strength 2.28 × 105 N/m² ASTM D 3574; equivalent to 33.0 psi
Compression deflection at 40% compression 6.96 × 104 N/m² CTM 0525; equivalent to 10.1 psi
Thermal conductivity 0.1338 W/(m·K) ASTM C 518; 2.54 cm-thick foam sample, density reported as 0.27 g/cm³
Linear coefficient of thermal expansion 3.2 × 10−4 cm/cm·°C CTM 0585; −25 to 150°C
Dielectric strength 165 V/mil CTM 0114; cured foam sample thickness 0.317 cm (0.125 inch)

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