Dowsil C60 vs Sika 825: Low Modulus Silicone Comparison
16 min reading time
Compare Dowsil C60 and Sika 825 low-modulus silicones. Learn the key differences in flexibility, adhesion, and performance to choose the right sealant for your job.
When it comes to low-modulus silicone sealants, two names regularly appear in the professional trade space — Dowsil C60 and Sika 825. Both are designed for flexible joints, perimeter seals, and glazing applications, offering long-term performance in demanding environments.
But what really sets them apart? In this comparison, we’ll explore their specifications, performance, and best uses to help you decide which one fits your project best — and why Dowsil C60remains a favourite among UK sealant professionals.
What Is Dowsil C60?
Dowsil C60 is a neutral-cure, low-modulus silicone sealant developed for internal and external construction joints. Manufactured by one of the world’s most trusted names in silicone technology, it’s formulated to deliver long-lasting flexibility, superior adhesion, and strong weather resistance.
C60 bonds effortlessly to both porous and non-porous substrates, including PVC-U, anodised aluminium, glass, painted surfaces, and metal cladding — making it suitable for a wide range of building applications.
Key Benefits:
Low-modulus, high elasticity (accommodates joint movement)
Neutral-cure for minimal odour and substrate compatibility
Excellent resistance to UV, weathering, and ageing
Adheres to a wide variety of surfaces without primer
Conforms to ISO 11600 F&G 25 LM
In short, Dowsil C60 is designed for professional users who need reliability and performance that endures.
What Is Sika 825?
Sika 825 is another high-quality neutral-cure, low-modulus silicone.It’s often used in glazing, curtain walling, and facade sealing applications. With excellent UV stability and a slow-skinning formula, it provides strong adhesion to common building materials such as glass, metal, and plastics.
It’s rated to ISO 11600 F25LM / G25LM, meaning it’s capable of accommodating up to ±25% movement — ideal for large expansion joints and architectural sealing where flexibility is critical.
Key Benefits:
Professional-grade neutral-cure formulation
Excellent movement capability and elasticity
Suitable for facade and weather-seal applications
Good colour range for architectural projects
Dowsil C60 vs Sika 825: Key Differences
Feature
Dowsil C60
Sika 825
Cure Type
Neutral-cure silicone
Neutral-cure alkoxy silicone
Modulus
Low-modulus, high elasticity
Low-modulus, high movement
Applications
Expansion joints, perimeter sealing, general construction
Façade, glazing, weather sealing
Colours Available
Broad range – white, black, buff, grey, brown
Wide architectural colour range
Adhesion
Excellent on porous & non-porous substrates
Excellent on glass, metal, plastic
Finish
Smooth, clean joint finish
Slightly slower skin time for large joints
Certification
ISO 11600 F&G 25 LM
ISO 11600 F25 LM / G25 LM
Analysis:
While both products provide impressive performance, Dowsil C60 is engineered for versatility and ease of useacross multiple substrates. Its formulation offers consistent results for construction joints, perimeter seals, and glazing applications.
Sika 825, meanwhile, is more specialised for façade systems and large movement joints — often in large-scale commercial projects. For most general construction and trade use, C60 delivers excellent performance with simpler handling and a proven brand heritage.
Which Sealant Should You Choose?
Both silicones are premium low-modulus options, but your choice depends on the project:
Choose Dowsil C60 if you need areliable, multipurpose, professional-grade sealant that performs on both interior and exterior joints.
Choose Sika 825 for architectural glazing or facade systems where high movement accommodation is the top priority.
If you’re searching for a Sika 825 alternativethat’s easier to work with and trusted by professionals across the UK, Dowsil C60 is the clear winner.
Where to Buy Dowsil C60
You can buy Dowsil C60 directly from The Seal Shop, with next-day delivery available across the UK.
We stock the full Dowsil professional sealant range, including sanitary, glazing, and construction silicones, all backed by expert product advice and trade-competitive pricing.
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