Neutral Structural Silicone Sealant for Curtain Wall

Structural bonding of glass curtain walls, aluminium panel and terracotta facades, metal structure engineering, and other architectural structural applications where the sealant transfers load.

PR-999 transfers wind load from the glass into the frame and is part of the structural design. Weatherseal products such as PR-520 or PR-666 keep water out of the perimeter joint and carry no load. A curtain wall usually uses both, in different positions, and the two must be chemically compatible.

Tensile adhesion strength 0.85 MPa against a 0.60 MPa minimum, elongation at maximum tensile strength 205%, and shear strength 0.89 MPa. Tensile adhesion after water immersion is 0.93 MPa. Test report 2025ML009 is available on request.

Yes — it is neutral cure, so no acetic acid is released to attack anodised surfaces or laminated glass interlayers. Alkane plasticizer is not detected, so there is no migration staining. Adhesion still has to be confirmed on the actual coating used on your project.

Standard OEM and private label MOQ is 1,000 pcs per model, with mixed-model trial orders from 3,000 pcs total and stock items from 500 pcs. Typical lead time is 15–25 days after artwork and sample approval.

Yes. Structural silicone caulk and structural silicone sealant are the same product under two trade words — "caulk" is what applicators call it, "sealant" is what specifications and test reports call it. What matters on a structural project is the standard the product is qualified to. PR-999 is tested to GB 16776-2025, which is the Chinese standard for structural silicone sealant, and report 2025ML009 is available on request.

A neutral structural silicone sealant does two jobs a weatherseal does not: it carries load and it is tested for stress at temperature. PR-999 is one-component neutral cure, tested to GB 16776-2025, with 0.85 MPa tensile adhesion at 23 °C, 0.71 MPa at 90 °C and 1.44 MPa at −30 °C, plus 0.89 MPa shear strength. General weatherseals such as PR-111 or PR-638 are not tested against those requirements. Report 2025ML009 is available on request.

Modulus is the stress needed to stretch the sealant a given amount, so a low modulus silicone sealant moves with the joint instead of fighting it, and it transfers less force into the glass or frame. For curtain wall and structural glazing work the usual requirement is a low-modulus or medium-modulus structural grade. PR-999 returns 205% elongation at maximum tensile strength and 0.85 MPa tensile adhesion at 23 °C, which places it in that class.

A high modulus silicone sealant is stiffer: it resists movement and pushes force back into the substrates, which is why it is used where a rigid bond is wanted and movement is small. A low-modulus grade absorbs the movement instead. Structural glazing normally specifies low or medium modulus, because the sealant has to accommodate thermal movement in the glass and framing. Send us the movement calculation and we will confirm whether PR-999 fits.

Yes, provided it is a structural grade and not a weatherseal. A structural silicone adhesive has to carry load, so it must be qualified to GB 16776 and tested for tensile adhesion, shear strength, and adhesion after heat and water-UV ageing. PR-999 is tested on all of those: 0.85 MPa tensile adhesion at 23 °C, 0.89 MPa shear strength, and 0.93 MPa after water and UV exposure. A general weatherseal such as PR-111 or PR-638 is not tested to that standard and must not be substituted.

Structural glazing silicone sealant bonds the glass to the frame so the sealant itself carries part of the wind load, which is why it is the product behind frameless facade and curtain wall appearance. It is also used for insulating glass secondary sealing and for bonding terracotta and aluminium panels to metal framing. PR-999 is specified for those applications; report 2025ML009 is available for your submittal.

Yes. A low modulus neutral silicone sealant is the right family for metal curtain walls, because neutral cure does not release acetic acid that would attack anodised aluminium. PR-999 is one-component neutral cure, tested to GB 16776-2025, with 205% elongation at maximum tensile strength — that combination is what keeps the bond line intact through thermal movement rather than transferring stress into the metal.

In our range only PR-999 is a structural grade, tested to GB 16776-2025. Everything else is a weatherseal or a speciality product. The distinction is not marketing: a structural grade has to pass tensile adhesion at 23 °C, 90 °C and −30 °C, shear strength, heat ageing and a check that no alkane plasticizer is present. If a quotation offers "structural silicone sealant" without those test results, ask for the report number.