CRL 33S Clear Silicone Sealant - Waterproof Glass & Window Caulk

• Our Most Popular Sealant
• Plastic Cartridges with Screw-On Nozzles
• Available in Eight Colors
• 24 Month Shelf Life*
• 10 Year Limited Warranty

CRL 33S Silicone (SKU: 33SC) is a professional-grade, one-component, room-temperature curing, acetic-cure 100% silicone elastomer. No activators, stabilizers, or catalysts required. Designed for durable, weatherproof seals and glazing—an economical, high-performance silicone sealant for commercial and residential projects.

Key Benefits & Differentiators

• High-temperature range: -80° to 400°F (-62° to 204°C) for demanding environments
• Cold-application capable: can be applied down to -35°F (-37°C)
• Strong physical properties: 350 psi tensile strength; 120 psi lap shear (1/8" / 3 mm); 25 ppi tear strength
• Mildew-resistant options for sanitary, tub & shower installations (clear, white, translucent white, tan contain fungicide)
• Certified for food-related equipment: Meets FDA 21 CFR 177.2600 and NSF Standard 51 (plastic materials/components in food equipment)
• Meets VOC limits and qualifies for LEED credits—low-VOC formulation

Basic Uses - Ideal for joining and sealing most non-porous building materials: glass, aluminum, stainless steel, wood, and many plastics. Common applications: curtainwall joints, steel & aluminum windows, skylights, bathtubs, showers, refrigerated trucks and walk-in freezers. Proper surface cleaning and tooling required. Cat. No. S1L2100 Primer may be required for some substrates.

Limitations - Not recommended for structural glazing or insulating glass glazing, concrete and stone expansion joints, horizontal decks, patios, driveways, or terraces subject to abrasion. Avoid use on concrete, marble, limestone, lead-coated, copper, brass, polyethylene or polypropylene, submerged joints (pools, aquariums), plazas, pavements, or surfaces with special protective/cosmetic coatings (mirrors, reflective glass). Not suitable for painting. Remove old sealant before applying new. See cartridge label and Specification Data Sheet for complete limitations.

Technical Data & Standards
Meets or exceeds:

• TT-S-001543A (COM-NBS) Class A — Silicone Building Sealants
• TT-S-00230C (COM-NBS) Class A — One-Component Building Sealants
• ASTM C-920 — Type S, Grade NS, Class 25, Use NT,