DOWSIL 748
Harmonization Code : 3919.10.80 | Other self-adhesive plastic rolls not exceeding 20 cm wide.
Main features
- Non-Corrosive Application Formulation
- 15-Minute Tack-Free Time
- 55 to 177 deg C Service Range
Product Description
DOWSIL™ 748 Non-Corrosive Sealant is a one-component, ready-to-use, non-slump silicone adhesive and sealant that moisture-cures at room temperature to form a tough, rubbery solid. Its alkoxy cure mechanism produces no corrosive by-products, supporting bonding and sealing around copper, electrical equipment, printed circuit board assemblies, and other corrosion-sensitive components. The off-white material develops a skin in approximately 15 minutes and becomes tack-free in less than 30 minutes at 25°C and 50% relative humidity. Once cured, it provides a Shore A hardness of 35, 350% elongation, electrical-insulation properties, and service capability from -55 to 177°C for extended periods, with shorter exposure up to 204°C.
Key features
- Non-corrosive alkoxy cure: Produces no corrosive cure by-products and is suitable for use around copper and other corrosion-sensitive metals.
- One-component, non-slump paste: Ready to apply without mixing, heating, or solvent-handling steps.
- Electrical properties: Typical dielectric strength of 475 V/mil and volume resistivity of 7.7 × 1014 ohm·cm after cure.
- Broad service-temperature capability: Suitable for extended exposure from -55 to 177°C and shorter exposure up to 204°C.
- Environmental resistance: Cured silicone resists moisture, ozone, corona, and weathering.
- Documented regulatory status: UL recognized and compliant with 21 CFR 177.2600 requirements when fully cured, washed, and used within applicable extractives limitations.
Applications / Suitable for
- Bonding and sealing electrical equipment and printed circuit board system assemblies
- Power and control connections, motors, junction boxes, control panels, and instrument assemblies
- General-purpose industrial bonding and sealing where low odor and non-corrosive cure are required
- Food-processing equipment applications requiring an appropriately cured and washed silicone material
TDS, SDS & Technical Documents
Technical Specifications
Physical Properties
General Properties
Mechanical Properties
Electrical Properties
Additional Information
DOWSIL™ 748 Non-Corrosive Sealant
A one-component, non-slump alkoxy silicone adhesive and sealant for general industrial and corrosion-sensitive electrical assemblies. The material cures with atmospheric moisture to form a tough rubber and combines non-corrosive cure chemistry with documented electrical properties, environmental resistance, and broad service-temperature capability.
As-supplied properties
Typical values measured at 25°C and 50% relative humidity unless otherwise stated. These values are not intended for specification writing.
| Property | Value | Unit | Method or condition |
|---|---|---|---|
| Consistency | Non-slump paste | — | As supplied |
| Extrusion rate | 150 | g/min | 1/8-inch nozzle at 90 psi |
| Skin-over time | 15 | min | At 25°C and 50% relative humidity |
| Tack-free time | 30 | min | At 25°C and 50% relative humidity |
| Cure time | 36 | hours | 1/8-inch section at 25°C and 50% relative humidity |
| Full cure | 7 | days | 1/8-inch section at 25°C and 50% relative humidity |
| Corrosion properties | Non-corrosive | — | Alkoxy cure mechanism produces no corrosive cure by-products |
Application and moisture cure
Apply the sealant to clean, prepared surfaces in a uniform layer. Cure progresses inward from surfaces exposed to atmospheric moisture, so joint thickness, exposed area, humidity, and substrate permeability affect the time required to reach the final cured state.
Store at or below 32°C in tightly sealed containers. Shelf life is 24 months from the date of manufacture when stored under the stated conditions. Because the material reacts with atmospheric moisture, reseal opened containers promptly. A cured plug may form in a tube tip during storage and can be removed without affecting the remaining material.
Cured physical and electrical properties
Typical cured values after seven days at 25°C and 50% relative humidity unless otherwise stated. Values are not intended for specification writing.
| Property | Value | Unit | Method or condition |
|---|---|---|---|
| Physical form | Tough, rubbery solid | — | After cure |
| Color | Off-white | — | Cured material |
| Specific gravity | 1.33 | — | At 25°C |
| Peel strength | 25 (4.4) | ppi (kN/m) | 1/4-inch steel strip bonded to aluminum |
| Durometer hardness | 35 | Shore A | ASTM D2240 |
| Tensile strength | 275 | psi | ASTM D412 |
| Elongation | 350 | % | ASTM D412 tensile specimen property |
| Dielectric strength | 475 | V/mil | ASTM D149 |
| Volume resistivity | 7.7 × 1014 | ohm·cm | ASTM D257 |
| Dielectric constant | 3.30 at 100 Hz 3.21 at 10 kHz |
— | ASTM D150 at 25°C |
| Dissipation factor | 8.7 × 10-3 at 100 Hz 2.8 × 10-3 at 10 kHz |
— | ASTM D150 at 25°C |
| Service temperature | -55 to 177 extended Up to 204 shorter exposure |
°C | Actual suitability depends on the specific application environment |
| UL status | Recognized to 105°C where elongation is not essential; UL 94 HB | — | UL File E40195 (N) |
| FDA status | Meets 21 CFR 177.2600 requirements when fully cured and washed | — | Subject to end-user compliance with applicable total extractives limitations |
Product resources
Evaluate DOWSIL™ 748 for your sealing application
Contact Krayden to discuss substrate preparation, bondline geometry, moisture-cure conditions, electrical requirements, regulatory considerations, packaging availability, or sample needs for DOWSIL™ 748 Non-Corrosive Sealant.
