DOWSIL 983™ Vs. DOWSIL 993™ for Structural Glazing

August 18, 2025

In the world of structural glazing, using the right material is key. We review two of Dow's most trusted materials for structural glazing applications— DOWSIL 983™ and DOWSIL 993™. This comparison guide should help you determine which one is right for your specific needs.

DOWSIL 983

DOWSIL 983 is a two-part, neutral-cure silicone sealant specially formulated for dual structural glazing and weather sealing applications. Along with having a high structural strength, it can form flexible and watertight bonds for long-term durability and weatherability.

Commonly used for curtainwall production or factory glazing, it is compatible with a variety of substrates, including aluminum, glass, and metal. The DOWSIL 983 sealant also meets ASTM C719 Class 25 (G, A, O) and ASTM C1184 structural glazing specifications.

Some other features and benefits of the DOWSIL 983 silicone sealant include:

• Higher movement capability ± 25%
• Primerless adhesion to many substrates
• Low VOC formula
• Low embodied carbon DOWSIL™ Silicone
• Green building certification

DOWSIL 993

DOWSIL 993 is another two-part, neutral-cure silicone that is commonly used to bond glass, metal, and other substrates in structural glass glazing applications. Along with a high level of mechanical properties, the DOWSIL 993 sealant has great weathering characteristics with a high resistance to UV radiation, heat, humidity, and ozone. It also has good temperature stability from -58°F to 302°F. It is great for impact-resistant window systems in new construction as well as retrofitting.

Some other features and benefits of DOWSIL 993 include:

• Primerless adhesion to many substrates
• Stable viscosity for A & B components
• Odorless formula
• Non-corrosive cure
• Carbon neutral by PAS 2060 standards

DOWSIL 983 Vs. DOWSIL 993

While both sealants are a popular choice for structural glazing applications, some important differences between DOWSIL 983 and DOWSIL 993 are outlined in more details below.

*Refer to the DOWSIL 983 datasheet and the DOWSIL 993 datasheet for more detailed product specifications.

Both sealants are an effective choice for many structural glazing applications. The DOWSIL 993 silicone sealant has a shorter working time if you are interested in a fast turnaround time and higher-speed production.

On the other hand, the DOWSIL 983 structural glazing sealant stands out because it is formulated for weather seal applications as well as structural glazing applications. Choose DOWSIL 983 when you are in need of a dual-function product with a high joint movement capability.

Regardless of whether you choose DOWSIL 983 or DOWSIL 993, these two-part silicones require exact ratio control. Inconsistent mixing and dispensing can lead to various issues, including problems with the structural integrity of the finished product or even bond failure.

For field glazing, consider space and portability. You would benefit from using a mixing and dispensing system that is compact, mobile, and does not require the use of electricity, such as the HG Little Bear silicone dispenser. Swing stage or scaffolding applications can add even more challenges to the equation as space is extremely limited and weight becomes a major consideration. A lightweight mixer and dispenser like the Skinny Bear silicone dispensing system is a great option since it is designed specifically for these types of glass glazing applications.

Dispensing.com is not affiliated with DOWSIL™. DOWSIL™ is a registered trademark of Dow Corning Corporation, a wholly owned subsidiary of The Dow Chemical Company.