By Product type

The Unique Properties of Silicones

Heat Resistance

Heat Resistance

Silicone fluid is extremely stable against thermal oxidation. For example, the dimethyl silicone fluid DM-FLUID is virtually unchanged when exposed to temperatures up to 150°C in air. Methylphenyl silicone fluid exhibits even better heat resistance than dimethyl silicone fluid and can be used for long durations in environments reaching 250°C.

Low-Temperature Resistance

Low-Temperature Resistance

Silicone fluid has excellent low-temperature resistance. DM-FLUID remains fluid even at -50°C. Methylphenyl silicone fluid was specially developed for low-temperature applications, so it remains fluid even in environments of -65°C. Since temperature has little effect on viscosity, these products are ideal for applications in cold regions.

Viscosity Stability

Silicone fluid shows little change in viscosity due to changes in temperature. It is thus ideal for use as instrument oil in instruments used in airplanes, automobiles, and trains, and for other applications that make use of silicone fluid's viscous properties. Low-viscosity (10 mm2/s and below) products aside, DM-FLUID offers the advantage of less temperature-dependent viscosity change than common mineral and synthetic oils or other silicone fluids.

Thermal Conductivity

The thermal conductivity of dimethyl silicone fluid is lower than that of common organic compounds (nearly the same as that of benzene and toluene) and is roughly 25% that of water. Although thermal conductivity increases with higher viscosities, it becomes nearly constant at viscosities above 100 mm2/s. The thermal conductivity of DM-FLUID is 2.4-3.5x10-4 cal/cm·sec·°C at viscosities below 20 mm2/s, and roughly 3.7-3.8x10-4 cal/cm·sec·°C at viscosities over 50 mm2/s.

Specific Heat

The specific heat of silicone fluid varies somewhat depending on viscosity, but is generally about one-third that of water. The values are comparable to common organic compounds that have low specific heat. The specific heat of DM-FLUID is 0.39-0.47 cal/g·°C for viscosities below 20 mm2/s, and approximately 0.36 cal/g·°C at viscosities over 100 mm2/s.

Chemical Stability

Silicone fluid is nearly chemically inert and is virtually unaffected by 10% alkaline aqueous solutions or 30% acid aqueous solutions at ambient temperatures. However, viscosity increases and gelation can occur if even trace amounts of acids or alkalis are introduced at high temperatures. Silicone fluid is almost unaffected by the presence of aluminum, stainless steel, and most other metals. However, lead, selenium, and tellurium can cause gelation. Precautions must therefore be taken during handling.


Corrosivity and Effects on Other Materials

Corrosivity and Effects on Other Materials

Silicone fluid has no adverse effect on metals, nor on most other substances. However, it may reduce the volume and weight of some rubber and plastic compounds due to extraction of the plasticizers when subjected to high temperatures. This tendency is especially strong for low-viscosity fluids. Particular care must be exercised when silicone fluid comes into contact with rubber sealing materials.


Surface Tension

Surface Tension

The surface tension of silicone fluid is much lower than that of water or common synthetic oils. Silicone fluids spread easily over the surfaces of various substances, and are thus widely used as release agents, defoamers, and ingredients for cosmetics.

Liquid Surface tension (mN/m)
DM-FLUID 16 to 21
Mineral oil 29.7
Water 72

Releasability and Nonadhesiveness

Releasability and Nonadhesiveness

The application of silicone fluid to mold surfaces prevents the adhesion of other materials, thereby enhancing mold releasability. Silicone fluids are widely used as release agents because they have excellent heat resistance and do not contaminate molds or molded materials.

Defoaming properties

Defoaming properties

Added in small amounts, silicone fluid has excellent defoaming action. Silicone fluid is primarily used as a defoamer for oil-based foaming fluids.

Water Repellency

Water Repellency

Silicone fluid also has excellent water repellency. The degree of water repellency can be represented by water contact angle, which is over 90° for DM-FLUID. An excellent and durable water-repellent coating can be obtained by applying F-9W-9 or DM-FLUID to glass, ceramic, or fiber using a bake-on process. Silicone fluid can also be used to improve the fluidity of powders and prevent coagulation.

Physiological Effects

Generally speaking, silicone fluid is physiologically inert and poses almost no risk to people or animals. Low-viscosity products excepted, DM-FLUID is nearly harmless unless ingested in large quantities. It is thus widely used as an ingredient in cosmetics.


Electrical Properties

The electrical properties of silicone fluid are extremely stable with respect to variations in temperature and frequency. Silicone fluid also withstands dielectric breakdown better than mineral oil. However, as with ordinary insulating oils, moisture absorption affects the electrical insulation properties of silicone fluid, so care must be taken to limit contact with moisture. Steps should be taken to dehydrate silicone fluid before using it as insulating oil in high-voltage transformers.

Resistance to Shear Stress

Silicone fluid has extremely high shear resistance, and it resists shear degradation at high speeds and high loads, meaning it has a long operating life. When synthetic or mineral oils pass through narrow gaps under pressure, shear stress destroys the oil molecules, causing a drop in viscosity. In contrast, with dimethyl silicone fluid of viscosities below 1,000 mm2/s, there is almost no change in viscosity. However, with high-viscosity products there may be an apparent drop in viscosity depending on the shear velocity. Note that this is not due to destruction of the molecules, so the viscosity returns to the initial level when the shear stress is removed. The shear resistance of silicone fluids is over 20 times greater than that of even top-quality petroleum-based oils.



Unlike mineral oil, silicone fluid exhibits extremely high compressibility and does not coagulate when pressurized. Silicone fluid has much higher compressibility than petroleum-based insulating oils or synthetic lubricants, and is thus well-suited for use as damper oil.



Silicone fluid is highly soluble in hydrocarbon solvents such as toluene, xylene, ligroin, and mineral spirits as well as in chlorinated hydrocarbons. However, it is insoluble in ethanol, methanol, and water.
*KF-56 is soluble in ethanol.



Although silicone fluid has many advantageous properties (eg. stable viscosity, high- and low-temperature resistance) that make it ideal for use as a lubricant, its poor boundary lubrication properties on steel-steel interfaces limit its use as a lubricant for such applications. However, silicone fluid does provide good lubrication for steel-bronze, steel-aluminum, steel-zinc, and wood-wood interfaces and for various combinations of plastics.

Radiation Resistance

In terms of radiation resistance, methylphenyl silicone fluid is superior to dimethyl silicone fluid, and the stability of radiation resistance increases proportionately with the amount of phenyl groups present in the molecules. Due to this property and its resistance to high and low temperatures, methylphenyl silicone fluid is widely used in the high-temperature parts of radiological equipment.

Page Top
Material Metal Silicone fluid DM-FLUID-50cs
Change in
Change in
Before heated storage - - - - - -
After heating to 150°C for 1,500 hours,
and before metal is inserted
- - - No change 0 ≥1014
Aluminum No change 0 0
Copper Moderate discoloration
Copper (tinned) Moderate discoloration
SUS 27 No change
Iron Moderate discoloration
Iron (cadmium plated) No change
Iron (nickel plated)
Iron (zinc plated)

Testing conditions: immersion for 1,500 hours at 150°C in sealed conditions.

Contact conditions Change in
appearance of
Silicone fluid DM-FLUID-100cs
Change in
change rate
Contact at room temp. No change No change 0
Contact at 70°C
Contact at 100°C
Contact at 150°C

Testing conditions: immersion for 500 hours at room temperature, 70°C, 100°C, and 150°C.

Material Change in plastic Change in silicone fluid
Weight change rate (%) Volume change rate (%) Appearance
Polyethylene -0.02 -0.09 No change
ABS resin -014 -0.16
Teflon +0.03 +0.15
Hard PVC 0 +0.05
Polystyrene -0.04 0
Phenol resin +0.30 +0.37
Methacrylic resin -0.02 +0.08
Polycarbonate +0.03 0
Acetal resin +0.02 +0.08
Nylon 0 -0.01
Cellulose triacetate +0.01 +0.05

Testing conditions: immersion for 500 hours at 70°C.

Material Contact conditions Volume chage rete (%)
Nitrile rubber 1 105°C / 250 h -6.7
Nitrile rubber 2 -8.5
Nitrile rubber 3 150°C / 200 h -6.0
Butyl rubber 105°C / 250 h -8.3
Styrene butadiene rebber -5.9
Chloroprene rebber -12
Neoprene rebber -12
Ethylene propylene diene polymer 150°C / 200 h -12
Acrylic rebber 150°C / 250 h -4.3
Fluoro-rebber (Viton®) +0.8
Silicone rebber KE-870-U 150°C / 250 h +37
Silicone rebber KE-765-U +41
Silicone rebber KE-951-U +50
Silicone rebber KE-550-U +51
FluoroSilicone rebber FE-271-U +0.5

Silicone fluid has major effects on silicone rubber,
with significant swelling of the rubber.
Lower viscosity fluids have greater effects.
In contrast, there is almost no swelling of fluorosilicone rubber.

Substance Contact angle (°)
Paraffin 108-116
Carnauba wax 107-125.3
DM-FLUID 90-110
Naphthalene 62
Nylon 70
Polyethylene 94
Polyvinyl chloride 87
Polystyrene 91
Polytetrafluoroethylene 108

When DM-FLUID is applied to a surface using a bake-on method,
the hydrophobic methyl groups (CH3-, shown below)
face outward, a state which results in water repellency.

1. Skin patch test

Testing method
Silicone fluid was applied on a patch to the inside of a human subjects' upper arm and the reaction observed with a microscope after 24 hours.

Test results

Grade Determination
DM-FLUIDL-5cs Quasi-negative
DM-FLUIDL-10cs Negative
DM-FLUIDL-100cs Negative

Determination standards

Naked eye
Irritation ranking B irritation
(Sample irritation index)
- (Control irritation index)
C irritation D irritation
Determination standards 0 1-2 3 ≥4 One or more
and assessment
Determination and
Negative Quasi-
Positive Positive Positive

Number of test subjects: 20 (Japanese Society for Cutaneous Health)

2. Eye irritation testing

Test conditions

Animal Japanese white rabbit
Sample DM-FLUID-5cs

Test results
Absolutely no effect on the cornea or iris.
There is slight inflammation of the conjunctiva,
but to a far lower degree than that caused by typical detergents.

3. Acute toxicity test*

Test conditions

Animal rat
Sample DM-FLUID-5cs

Test results
LD50 is over 5,000 mg/kg for both males and females.

*Acute toxicity test
Generally speaking, this test determines the amount of a substance that constitutes
a lethal dose when administered at one time to a test animal.
It is usually expressed as "LD50" (50% Lethal Dose).
Please refer to the following table of degree of toxicity.

Classification based on strength of toxicity

Degree of toxicity* Oral LD50 (rat)
(unit: mg/kg)
Very toxic ≤25
Toxic 25-200
Harmful 200-2000

The arc resistance of silicone fluids is about the same as that of ordinary mineral oil-based insulating oils. Table shows the results of tests conducted to determine the amount of gases emitted and amount of deposits caused by arcing.

Gases emitted during arcing (comparison with other oils)

Material Gas quantity
per 1,000 arcs
Composition of non-oil gas discharges (Vol. %) Gas deposits
(carbon, other)
per 1,000 arcs
H2 CO CO2 CH4 C2H4 C2H2 Except
Silicone fluid 9.9 50.6 2.6 0.5 5.8 0.5 0 0.5 39.5 26
Common insulating oil 6.2 48.8 1.3 0 4.5 0.7 3.3 0.7 40.7 13
Liquid paraffin 7.0 49.4 2.4 0.4 2.4 1.2 2.4 0.6 41.2 14

DC intermittent arc method Applied voltage:
100 V Tungsten electrode (From Degradation of Insulating Oils Due to Arcing, a technical report by the Insulating Oil Division)

F-6W-9 F-9W-9 KF-965 F-5W-0 KF-54 KF-56
DM-FLUID-1,000cs -

: Dissolves transparently at room temperature
: Clouds or separates at room temperature

Solvent Results
Solvent naphtha
Industrial gasoline
Mineral spirits
Diisopropyl ether
Hexyl ether
Ethyl acetate
Butyl acetate
Isopropyl laurate
Isopropyl palmitate
Isopropyl myristate
Methyl ethyl ketone
Methyl isobutyl ketone
Lauryl alcohol
Amyl acetate
Glacial acetic acid
Naphthene-based lubricating oils
Ethylene glycol
Diethylene glycol stearate
Propylene glycol
Liquid paraffin
Paraffin wax
Lubricating oils
Fatty acids
(other than glacial acetic acid)
Animal and vegetable oils
Methyl phthalate

: Dissolves
: Partially dissolves
: Does not dissolve (results at room temperature)