Choosing the right low modulus silicone sealant can make all the difference in durability, flexibility, and overall finish. Two of the most popular options on the UK market are Bond It WP100 and Dowsil 791 — but which one is right for your next job? In this guide, we break down the differences, strengths, and best-use scenarios for each product so you can make the right choice.

 

Overview: What Are Low Modulus Silicone Sealants?

 

Low modulus silicones are designed for high movement joints, excellent flexibility, and strong weatherproofing. They’re widely used for:

• Window perimeter sealing
• Glazing systems
• External cladding
• uPVC frames
• Expansion joints

 

Both Bond It WP100 and Dowsil 791 fall into this category — but they’re not identical, and that’s where choosing the right one matters.

Quick Comparison Table

Feature	Bond It WP100	Dowsil 791
Cure Type	Neutral Cure	Neutral Cure
Movement Capability	±25%	±50%
Best For	General glazing, uPVC, internal & external sealing	Façade systems, external weather sealing, high-movement joints
Mould Resistance	Good	Excellent
Colours	White, Clear, Black (varies)	Wide range (White, Grey, Black, Bronze etc.)
Price	More cost-effective	Premium price point
Adhesion	Strong on most surfaces	Outstanding on glass, metal, coated substrates
Brand Recognition	Strong trade brand	Industry leader (Dowsil)

 

 

Bond It WP100 – Best Value for Everyday Glazing & External Sealing

 

Bond It WP100 is a reliable, high-performance LMN silicone ideal for installers who need strong adhesion and excellent flexibility without paying premium brand prices.

 

Why choose WP100?

• Great value for everyday use
• Reliable adhesion on glass, metal, uPVC & cladding
• Strong weather resistance
• Suitable for expansion joints and perimeter sealing
• Excellent for both domestic and trade installers

 

WP100 is the best choice when you want dependable performance at a more competitive price point.

 

Dowsil 791 – Premium Weather-Sealing for High-Movement Joints

 

Dowsil 791 is one of the most trusted LMN silicones in the world. Known for its outstanding movement capability (±50%), it’s suited to high-performance commercial and industrial applications where long-term durability is essential.

 

Why choose 791?

• Industry-leading flexibility and joint movement
• Exceptional resistance to UV, rain, wind and temperature changes
• Perfect for curtain walling and façade systems
• Outstanding adhesion to glass and coated metals
• Extremely durable, long-lasting finish

 

Choose 791 when you need the most robust weatherproofing and maximum service life.

 

Which Sealant Should You Choose?

 

Choose Bond It WP100 if you want:

 

✔ Great value without sacrificing performance

✔ Strong adhesion for uPVC and general glazing

✔ Reliable external weatherproofing

✔ A cost-effective solution for frequent use

 

Choose Dowsil 791 if you want:

 

✔ Maximum joint movement and flexibility

✔ Premium weather protection for external façades

✔ A sealant trusted on commercial architectural projects

✔ Long-term performance in harsh environments

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Final Verdict

 

Both products are excellent LMN silicones — but they shine in different areas.

• WP100 gives you outstanding performance at a lower price, making it ideal for everyday glazing, uPVC sealing, and internal/external use.
• Dowsil 791 is the premium choice for facades, curtain walling, and any project needing maximum movement capability and the best long-term durability.

 

For many installers, WP100 handles 90% of jobs — and 791 is reserved for the high-spec projects.

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