Best Window Glazing Sealant for Restoration: 2025 Expert Review
DR Joinery
Expert Joiner & Restoration Specialist
Choosing the right glazing sealant is arguably the most critical part of finishing a window restoration, yet it is often an afterthought. In York, where we battle driving rain and fluctuating temperatures, a failed seal leads to blown units, drafty sashes, and eventually, rot in your timber frames.
Traditional joinery moves; timber expands in winter and shrinks in summer. If your sealant is too rigid or doesn't adhere properly to both the glass and the wood, water will find a way in. I often see DIY repairs where the wrong silicone was used, trapping moisture against the wood and accelerating decay.
In this review, I'll compare three sealants I keep in the van: a solid industrial budget option for bedding glass, a high-performance outdoor sealant for perimeter weatherproofing, and a specialist paintable acrylic that solves the nightmare of finishing internal beads.
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Specs vs. The Real World
The Spec: "Paintable Silicone"
"Many products claim to be 'all-in-one' solutions that you can paint over."
True silicone repels paint. If you act on a 'paintable' claim with standard silicone, your paint will bead up and flake off. For internal joinery that needs painting, you must use an acrylic or hybrid sealant, not pure silicone.
The Spec: "Lifespan Guarantees"
"Manufacturers often print '25-year guarantee' on the tube."
In the real world, exposed to York's damp climate and UV levels, even the best sealant needs checking every 10 years. Preparation is key; if the surface wasn't clean and dry, the best sealant in the world will fail in six months.
My Top 3 Recommendations
Three options to cover different needs and budgets
Everbuild – Everflex – 225 Contract Industrial & Glazing Silicone
Everbuild
This is a staple 'builder grade' silicone. It is an acetoxy cure sealant (you will smell the vinegar), which makes it affordable and fast-curing. It is excellent for bedding glass units into frames where you want a reliable, invisible seal that won't be painted over. It does the job without fuss.
The Good
- Excellent locking price for trade usage
- Contains anti-fungal compound to prevent black mould
- Fast skinning time (10 mins) helps if rain is threatened
The Bad
- Strong vinegar smell (acetoxy) during application
- Cannot be painted over (strictly for glass/glazing lines)
Installer Tip:
Use this primarily for 'bedding' the glass—running the bead that the glass sits against. It cures quickly and prevents water ingress around the rebate. Do not use this for the final front bead if you intend to paint the window.
Priced at £4.48 at the time of writing
Check Price on AmazonUniBond 2078170 Outdoor Window and Door Frame Sealant
Unibond
When sealing the perimeter of a window (where the wooden frame meets the brick or stone), flexibility is non-negotiable. This UniBond outdoor sealant provides a robust, waterproof seal that accommodates the movement of the building without cracking. It offers superior adhesion to uPVC and painted timber compared to cheaper alternatives.
The Good
- Permanently flexible – essential for older properties
- Excellent adhesion to mixed materials (wood to brick)
- Truly waterproof perimeter seal
The Bad
- More expensive than contract silicone
- Requires a completely dry substrate for proper adhesion
Installer Tip:
For a neat finish on external frames, mask the brickwork and the frame with tape before applying. Smooth the bead with a tool dipped in soapy water, then remove the tape immediately. It creates a crisp, professional line that prevents water sitting on the edge.
Priced at £10.67 at the time of writing
Check Price on AmazonUniBond Indoor Window & Door Frame Sealant
Unibond
This is an acrylic sealant, not a silicone, and that is its superpower. Traditional joinery often involves timber beading that needs to be painted to match the sash. You cannot paint silicone. This product fills the gaps between your internal decorative beads and the frame, dries in an hour, and can be painted over flawlessly.
The Good
- Paintable from just 1 hour – speeds up the job
- Water-based, so easy clean-up with a damp cloth
- Perfect for internal staff beads and skirting
The Bad
- Not for exterior use (will wash out before curing if rained on)
- Less flexible than silicone for high-movement joints
Installer Tip:
I use this strictly for the 'finishing touches' inside. When fitting new staff beads on a sash window, run a thin bead of this along the join. Wipe it smooth with a wet finger, wait an hour, and then paint your top coat. It makes the joinery look seamless and solid.
Priced at £6.00 at the time of writing
Check Price on AmazonFrequently Asked Questions
Why can't I just use cheap silicone for everything?
Should I use putty or silicone for sash windows?
How do I remove old silicone from wood?
Can I paint over these sealants?
I have a listed property in York, what should I use?
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