LOCTITE SI 593
Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others

Main features
- Non-Slumping Sealant Formulation
- Adhesion and Flexibility
- Seals Out Moisture and Contaminants
Product Description
LOCTITE® SI 593™ BLACK is a one-component, room-temperature vulcanizing (RTV) acetoxy silicone sealant designed to provide durable sealing and bonding for a wide variety of mechanical assemblies. Upon exposure to atmospheric moisture, it cures to form a tough, flexible silicone rubber seal that resists aging, weathering, UV exposure, ozone, and thermal cycling without hardening, shrinking, or cracking. The product offers superior adhesion and flexibility and is suitable for electrical insulation, trim bonding, and sealing of ducts, vents, flues, doors, and windows.
Key Features & Benefits
- One-component RTV acetoxy silicone sealant.
- Non-slumping thixotropic formulation.
- Superior adhesion and flexibility.
- Seals out moisture and contaminants.
- Fills large cracks and seams.
- Resists UV, ozone, weathering and thermal cycling.
- Non-flammable and non-toxic.
- UL 94HB classified at 1.9 mm cross section.
Recommended Applications
- Electrical insulation.
- Protection of leads from mechanical shock.
- Trim bonding applications.
- Sealing ducts, vents and flues.
- Sealing doors and windows.
- General-purpose mechanical assembly sealing.
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Additional Information
As-Supplied / Before-Processing Properties
| Property | Value | Unit | Condition |
|---|---|---|---|
| Technology | Silicone | — | RTV sealant |
| Chemical Type | Acetoxy Silicone | — | Moisture-curing silicone |
| Appearance | Black | — | Uncured material |
| Components | One Component | — | No mixing required |
| Viscosity | Thixotropic Paste | — | Non-slumping |
| Odor | Acetic Acid | — | Characteristic cure odor |
| Specific Gravity | 1.01 | — | 25°C |
| Extrusion Rate | ≥250 | g/min | Typical |
| Tack-Free Time | ≤60 | minutes | Surface cure |
After-Processing / Final-State Properties
| Property | Value | Unit | Condition / Method |
|---|---|---|---|
| Full Cure Time | 24 | hours | Moisture cure at ambient conditions |
| Tensile Strength | ≥1.5 | N/mm² | ISO 37, 1 week cure |
| Elongation at Break | ≥300 | % | ISO 37 |
| Shore Hardness | ≥18 | Shore A | ISO 868 |
| Environmental Resistance | Excellent | — | Resists weathering and aging |
| Thermal Cycling Resistance | Excellent | — | Will not harden, shrink or crack |
| UV Resistance | Excellent | — | Outdoor sealing applications |
| Ozone Resistance | Excellent | — | Long-term durability |





















