Silicone vs Hybrid Sealant: Which Is Better For Your 2026 Installs?
Choosing the right sealant is the difference between a job that lasts decades and a callback within six months. In 2026, the technology behind Silicone and Hybrid sealants has reached a point where the "correct" choice depends entirely on your specific substrate and environment.
At Glazing Supplies Direct, we stock industry-standard brands like Soudal and Dow Corning (Dowsil) because they provide predictable, trade-grade results. This guide breaks down the technical differences to help you decide which tube to load into your gun for your next install.
What is Silicone Sealant?
Silicone sealant is a synthetic polymer made from silicon, oxygen, carbon, and hydrogen. It has been the trade standard for decades due to its incredible flexibility and resistance to the elements.
There are two main types of silicone you will encounter:
- Acetoxy Silicone: Known for its "vinegar" smell. It is fast-curing and ideal for sanitary applications.
- Neutral Silicone: This has a lower odor and is safer for sensitive materials like stone or PVC, as it doesn't release acid during the curing process.
Why use Dowsil 785 or 791?
Dowsil 785 is the gold standard for sanitary applications. It contains fungicides to resist mold growth in high-moisture areas like bathrooms and kitchens.
Dowsil 791 is a low modulus weatherproofing silicone. It is specifically designed for building facades, glazing joints, and window frame perimeters. It offers ±50% movement capability, meaning it can expand and contract significantly without cracking or peeling.
What is Hybrid Sealant?
Hybrid sealants, such as the Soudal Fix ALL range, combine the best properties of silicone and polyurethane. They utilize SMX Hybrid Polymer technology to provide high-strength bonding and sealing in one product.
Hybrids are often referred to as "grab adhesives" because they have a higher initial tack than standard silicone. They can be applied to wet surfaces and are generally much tougher once fully cured.
Why use Soudal Fix ALL?
Soudal Fix ALL is versatile. It is 100% paintable, unlike silicone which repels paint. If you are sealing a joint that needs to match a specific wall color, a hybrid is your only option. It also bonds to almost any surface, including damp masonry and metal, without the need for a primer.
Comparison: Silicone vs. Hybrid at a Glance
| Feature | Silicone (Dowsil 791/785) | Hybrid (Soudal Fix ALL) |
|---|---|---|
| Flexibility | High (Up to 50% movement) | Medium (Up to 25% movement) |
| Adhesion | Excellent on glass/ceramic | Universal (Masonry, Metal, Wet surfaces) |
| Paintability | No | Yes |
| UV Resistance | Superior | High |
| Cure Time | 24–48 hours | Fast (Soudal Turbo cures in 20 mins) |
| Initial Grab | Low | High |
Why is Flexibility Critical for 2026 Installs?
As building regulations and thermal performance standards tighten, the movement in window and door frames increases. Temperature fluctuations cause uPVC and aluminum frames to expand and contract.
If you use a sealant with low flexibility (low movement capability), the bead will eventually pull away from the substrate, leading to air leaks and water ingress.
- Low Modulus Silicones (like Dowsil 791) are soft and stretchy. Use these for wide joints or areas with high movement.
- High Modulus Hybrids (like Soudal Fix ALL Turbo) are stiffer. Use these for structural bonding or where the joint is small and needs to resist impact.
Pro Tip: Check Your Substrate Compatibility
Before applying, ensure your surface is clean. While Soudal Fix ALL can bond to damp surfaces, Dowsil silicones require a bone-dry substrate to achieve a chemical bond. Always use a glazing shovel or multi-pack utility spreaders to tool the joint immediately after application for a professional finish.
When Should You Choose Silicone?
- Sanitary Areas: Use Dowsil 785 for anything involving baths, showers, or sinks. Its mold-resistance is superior to most hybrids in constant wet conditions.
- Exterior Glazing: For perimeter sealing of window frames where maximum movement is expected, Dowsil 791 is the reliable choice.
- Glass-to-Glass Joints: Silicone provides the clearest, most aesthetic finish for glass partitions or shopfronts.
When Should You Choose a Hybrid?
- Painting is Required: If the customer wants the sealant to "disappear" into the wall color, use Soudal Fix ALL Flexi.
- Emergency Repairs: Hybrids can be applied in the rain. If you have a leak on a damp day, a hybrid will bond where silicone will fail.
- Heavy Bonding: If you are fixing cladding or heavy trim and don't want to use mechanical fixings, the Fix ALL Xtreme provides massive initial hold.
Factors to Consider Before Buying
- UV Exposure: For south-facing windows, silicone generally holds its color and integrity longer than older hybrid formulas. However, modern SMX polymers from Soudal are highly UV-stable.
- Tooling Ease: Silicone is generally easier to "tool" (smooth out) than hybrids. Hybrids are thicker and more "grabby," requiring a bit more skill and a good finishing spray.
- Cost: While hybrid sealants are often slightly more expensive per tube, they can save money by reducing the need for primers and allowing for faster job completion.
How to Apply Sealant for a Trade Finish
- Clean the joint: Remove all old sealant, dust, and grease.
- Insert Backer Rods/Packers: If the joint is deep, use glazing packers or backer rods to control the depth.
- Cut the Nozzle: Cut the nozzle at a 45-degree angle to the width of the joint.
- Apply Constant Pressure: Run a continuous bead. Avoid stopping and starting.
- Tool Promptly: Use a smoothing tool or spreader. Do not use your finger with saliva, as bacteria can encourage mold growth later.
Frequently Asked Questions (FAQ)
Can I put silicone over old silicone?
No. New silicone will not bond to old silicone. You must completely remove the old material using a blade or chemical remover before applying a new bead.
Is hybrid sealant waterproof?
Yes. Once cured, hybrid sealants like Soudal Fix ALL are completely waterproof and can even be used for underwater repairs in some instances.
Can I use Dowsil 791 inside?
Yes. It is safe for internal use, though it is primarily designed for external weather-sealing. For bathrooms, however, Dowsil 785 is better due to its anti-fungal properties.
Is hybrid sealant better than "No More Nails"?
Soudal Fix ALL is a professional-grade hybrid polymer, which is significantly more flexible and durable than standard solvent-based construction adhesives. For glazing and exterior work, the hybrid is vastly superior.
Order Your Trade Essentials Today
At Glazing Supplies Direct, we don't make you jump through hoops for trade pricing. Whether you need a single tube of Dowsil 791 for a home repair or a pallet of Soudal Fix ALL for a commercial contract, we have the stock ready to ship.
- Free UK Delivery on orders over £50.
- Next-Day Delivery available on all in-stock items.
- No Trade Account Required.
Browse our full range of Sealants and Adhesives here or pick up your Glazing Packers and Installation Tools to get the job done right the first time.