DOWSIL™ 3140 RTV Coating

Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others

DOWSIL™ 3140 RTV Coating

Main features

  • One-part silicone coating for room-temperature curing
  • Resistant to moisture, chemicals, and UV
  • Low viscosity for uniform coating and complete coverage

Product Description

DOWSIL™ 3140 RTV Coating is a one-part, room-temperature vulcanizing silicone coating designed to provide durable environmental and electrical protection for electronic components and assemblies. It features low viscosity for easy application, strong adhesion, and excellent dielectric performance. Upon curing, it forms a flexible, protective coating resistant to moisture, chemicals, and temperature extremes.

Product Key Features

  • One-part silicone coating for room-temperature curing
  • Low viscosity for uniform coating and complete coverage
  • Excellent dielectric strength and electrical insulation
  • Flexible, durable protective layer
  • Resistant to moisture, chemicals, and UV
  • Operating temperature range: -55°C to 200°C
  • Good adhesion to various substrates
  • Non-flammable and UL recognized for electrical applications

Applications

  • Coating of printed circuit boards (PCBs)
  • Encapsulation of sensors and electronic modules
  • Protection of connectors, relays, and transformers
  • Industrial and automotive electronics
  • Moisture and corrosion protection for sensitive electronics
  • General electrical insulation and protective coating 
Product Family

DOWSIL 3140

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TDS, SDS & Technical Documents

Technical Specifications

General Properties
Color
The color
Clear to slightly hazy smooth viscous liquid
Specific Gravity
Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume. For liquids, the reference substance is almost always water (1), while for gases, it is air (1.18) at room temperature. Specific gravity is unitless.
1.05
Physical Properties
Viscosity
Viscosity is a measurement of a fluid’s resistance to flow. Viscosity is commonly measured in centiPoise (cP). One cP is defined as the viscosity of water and all other viscosities are derived from this base. MPa is another common unit with a 1:1 conversion to cP. A product like honey would have a much higher viscosity -around 10,000 cPs- compared to water. As a result, honey would flow much slower out of a tipped glass than water would. The viscosity of a material can be decreased with an increase in temperature in order to better suit an application
34400 mPa.s
Mechanical Properties
Elongation
Elongation is the process of lengthening something. It is a percentage that measures the initial, unstressed, length compared to the length of the material right before it breaks. It is commonly referred to as Ultimate Elongation or Tensile Elongation at break.
419 %
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.
15 kV/mm
Thermal Properties
UL 94 Rating
Flammability rating classification. It determines how fast a material burns or extinguishes once it is ignited. HB: slow burning on a horizontal specimen; burning rate less than 76 mm/min for thickness less than 3 mm or burning stops before 100 mm V-2: burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed. V-1: burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed. V-0: burning stops within 10 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed. 5VB: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole. 5VA: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole
V-1

Additional Information

Frequently Asked Questions About DOWSIL™ 3140 RTV Coating

What are typical applications for DOWSIL™ 3140?

DOWSIL™ 3140 is used for protective coating and encapsulation of electronics, including:

  • Coating PCBs and power modules
  • Encapsulation of sensors and instrumentation
  • Protection of connectors, relays, and transformers
  • Moisture and corrosion prevention in electronics

Why choose DOWSIL™ 3140?

This RTV coating offers excellent flowability, long-term flexibility, and strong adhesion. Its protective properties make it ideal for electronics operating in harsh environments or exposed to moisture and contaminants.

How does it cure?

DOWSIL™ 3140 cures at room temperature upon exposure to atmospheric moisture, forming a flexible, durable silicone layer. Typical cure times vary with coating thickness and humidity.

What application methods are supported?

The material can be applied by brushing, dipping, spraying, or automated dispensing to provide uniform protective coatings.

What surface preparation is required?

Ensure substrates are clean, dry, and free from oils, dust, or flux residues for optimal adhesion and performance.

Is the coating repairable?

Yes, cured coatings can be carefully removed or cut for repair. Additional RTV can then be applied to restore protection.

Learn More About DOWSIL™ 3140

DOWSIL™ 3140 RTV Coating is engineered to provide durable protection for electronic systems exposed to moisture, chemicals, and extreme temperatures. This one-part silicone coating delivers reliable electrical insulation, long-term flexibility, and strong adhesion across a variety of industrial and electronics applications.


Main Advantages of DOWSIL 3140

easy application

Low viscosity allows uniform coating over complex geometries and fine features.

moisture & chemical resistance

Provides durable protection against water, chemicals, and environmental stress.

thermal stability

Stable performance over a wide temperature range for harsh environments.

insulating performance

High dielectric strength ensures reliable electrical insulation.

How to Choose a Coating

  • ✔ Cure requirements and processing method
  • ✔ Electrical insulation needs
  • ✔ Environmental exposure and stress
  • ✔ Application method (brush, dip, spray)
  • ✔ Thermal and chemical resistance requirements

Compliance You Can Trust ✅

  • UL recognized for electrical insulation
  • RoHS / REACH Compliant
  • Durable protection for sensitive electronics

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