WR550 Weather-Resistant
Silicone Sealant

WR550 is designed for exterior weather-sealing joints where regular movement, UV exposure, rain and temperature changes are expected. It is classified to GB/T Class 35 with ±35% movement capability, records 93% elastic recovery and 0 mm vertical sag, and has conditioned adhesion evidence on anodized aluminum and float glass. A general-purpose neutral silicone may be suitable for simpler sealing work, but WR550 provides more specific performance data for moving building-envelope joints.

No. WR550 is a non-structural weatherseal and is not intended to transfer permanent structural loads or replace a structural glazing silicone. Its role is to seal compatible facade, curtain-wall perimeter, roofing, window and door joints against weather while accommodating joint movement. Where the sealant is expected to retain glass or carry structural load, a separately qualified structural glazing silicone should be specified instead.

WR550 has type-test adhesion evidence on anodized aluminum and float glass. Coated aluminum, other coated metals, concrete, masonry, rendered surfaces, plastics, membranes and natural stone should be evaluated using the actual project materials before specification. Coatings, porosity, contamination and adjacent materials can change adhesion or staining behavior, so a material name alone is not enough to confirm compatibility.

At 23°C and 50% relative humidity, WR550 typically forms a surface skin in about 25 minutes, becomes tack-free in about 1 hour and cures inward at approximately 2–3 mm per 24 hours. Tack-free does not mean fully cured. A 7 mm-deep bead may require about 7 days under standard conditions, while deeper joints, lower temperatures, lower humidity or restricted air circulation can extend the cure time.

Current WR550 guidance starts with a minimum joint width of 6 mm and a minimum sealant depth of 6 mm, with a maximum recommended sealant depth of 15 mm. A width-to-depth ratio of about 2:1 is preferred for typical movement joints. A compatible closed-cell backer rod or bond-breaker tape should be used where needed to control depth and maintain two-sided adhesion rather than three-sided bonding.

WR550 is available in 300 mL cartridges packed 24 per carton and 600 mL foil sausages packed 20 per carton. Current listed colors are black, white, grey and clear. Project-specific colors can also be discussed based on the required quantity, color reference and destination market. Buyers should confirm the required package format and color when requesting samples or quotations.

Project-specific grey color matching can be discussed for WR550 when the facade, curtain-wall frame, window profile or cladding system requires the sealant to coordinate with the surrounding finish. Typical architectural grey references that buyers may specify include RAL 7016 Anthracite Grey, RAL 7024 Graphite Grey and RAL 7039 Quartz Grey.

The required RAL reference should be confirmed before production because “grey” can cover noticeably different tones, and the final sealant color should be approved against the intended project finish or agreed color reference. Custom color availability depends on the required quantity and production scope, so these RAL references should be treated as project color-matching examples rather than standard stock-color claims.

The 600 mL foil sausage format is generally more practical for professional projects that require higher-volume dispensing, while the 300 mL cartridge is convenient for smaller jobs, maintenance work or applications where cartridge guns are already standard. WR550 is offered in both formats. The sausage version requires a compatible sausage gun, and buyers should confirm the required package format, quantity, color and destination market before ordering.