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Revison Date: September 2026
The best silicone sealant for most UK trade and manufacturing jobs is a neutral cure, low modulus silicone such as Soudal Silirub 2, because it bonds primerless to glass, metals, plastics, masonry and wood, stays flexible and resists UV and weather. Where a joint sits in a wet or hygienic area, choose an anti-fungal sanitary grade; where you are glazing or sealing glass and metal on a budget, an acetoxy silicone does the job quickly and cleanly.
This guide explains how silicone sealant works, where it fails, and how to choose between neutral cure and acetoxy, clear and coloured, and sealant versus silicone adhesive. It covers glazing, bathrooms, kitchens, window perimeters, cold rooms and industrial joints, with product picks from Ureka’s live range and the data from each Technical Data Sheet.
For a durable, flexible, water-resistant joint, use a neutral cure silicone sealant like Soudal Silirub 2 on mixed construction materials, Soudal Silirub 2/S in bathrooms, kitchens and cold stores, and an acetoxy clear silicone sealant such as Soudal Silirub 1 or Everbuild 225 for glass, ceramic and metal. For mirrors, use a dedicated silicone adhesive such as Soudal Mir-o-bond.
| Application | Best Ureka choice | Why |
|---|---|---|
| Mixed materials, construction and movement joints | Soudal Silirub 2 | Neutral cure, low modulus, primerless on glass, metals, plastics, masonry and wood |
| Bathrooms, kitchens, cold storage | Soudal Silirub 2/S | Sanitary grade with anti-fungicidal agent; food contact certificate available |
| Clear glazing, sanitary and kitchen sealing | Soudal Silirub 1 | 100% silicone clear acetoxy, anti-mould, fast skinning |
| Industrial glazing, glass to glass and metal | Everbuild 225 Industrial & Glazing | Mid modulus acetoxy, service temperature up to +200°C |
| Contract sanitary and trim sealing | Everbuild 200 Contractors | Cost-effective anti-fungal acetoxy for smooth, non-porous surfaces |
| Window and door perimeter sealing | Aro-Seal 1162 | Neutral oxime cure with uPVC adhesion promoters, EN 15651-1 F EXT-INT |
| Bonding mirrors | Soudal Mir-o-bond | Neutral silicone adhesive that does not attack mirror backing |
Silicone sealant is a one-component, moisture-curing paste based on polysiloxane. It is gunned from a cartridge into a joint, tooled smooth, and then reacts with humidity in the air to form a flexible, rubber-like seal. Because it cures from the surface inwards, it forms a skin within minutes but takes a day or more to cure through, depending on bead size.
Once cured, a good silicone sealant stays elastic over a very wide temperature range, resists UV, rain and snow, and does not shrink when it is a 100% silicone formulation. That combination is why it is the default choice for glazing, sanitary joints and weather seals.
The biggest difference between silicones is the cure chemistry. Acetoxy silicones release acetic acid as they cure, which gives the familiar vinegar smell. They skin quickly and bond well to glass, ceramic and many metals, but can attack sensitive surfaces such as some metals, natural stone and mirror backings.
Neutral cure silicones (oxime or alkoxy types) release a neutral by-product. They have a lower odour and are kinder to metals, masonry and plastics, which makes them the safer choice on mixed or unknown substrates.
Modulus describes how stiff the cured sealant is. A low modulus silicone sealant stretches easily and puts less stress on the joint edges, so it suits movement joints, facades and perimeter sealing. Mid and high modulus grades are firmer and tougher, which suits glazing, gaskets and industrial joints where movement is limited.
A silicone sealant is designed to fill and seal a gap. A silicone adhesive is formulated to hold a component in place, for example a mirror on a wall. Some sealants can fix light trims, but where the load is carried by the silicone, use a product designed as an adhesive.
A silicone sealant joint looks simple, but the wrong grade causes most of the call-backs that installers and manufacturers see. The main risks are:
Choosing the right silicone sealant for the substrate, movement and environment avoids all of these problems.
Soudal Silirub 2 is a premium, low modulus, neutral cure silicone sealant. It is 100% silicone with no shrinkage, thick-bodied and easy to tool, with primerless adhesion on glass, plastics, masonry, metals and wood.
The Technical Data Sheet gives a skin time of about 5 minutes and a cure rate of about 2 mm per 24 hours (20°C, 65% RH), temperature resistance from -60°C to +180°C, and a maximum allowed distortion of 25%. It is listed on site in clear, brilliant white and RAL 7016 anthracite.
Choose it for: construction and movement joints, topsealing glazing, and joints between treated wood, metal, PVC profiles and glass. Avoid it on: natural stone such as marble or granite (staining risk), and polycarbonate or acrylic (PMMA), where the TDS warns of stress cracking.
Soudal Silirub 2/S is a premium low modulus, neutral cure sanitary silicone with a powerful anti-fungicidal agent. It has primerless adhesion on sanitary materials, including plastics, and a food contact certificate is available. The TDS lists sanitary and kitchen joints, glazing, container and cold-storage applications and air conditioning sealing. It is offered in brilliant white, grey and transparent.
Soudal Silirub 1 is a clear, low modulus acetoxy silicone sealant in a 310ml cartridge. It is 100% silicone, anti-mould and weather resistant, with primerless adhesion on glass, ceramic, porcelain, stainless steel, aluminium and wood. The TDS gives a skin time of about 7 minutes and resistance from -60°C to +180°C. Do not use it on PVC, PE, PP, PTFE or bituminous surfaces.
Everbuild 225 is a mid modulus acetoxy silicone for single glazing, butt and channel glazing, glass to glass and glass to aluminium, gasket sealing and refrigeration and hygiene sealing. The data sheet lists 20% movement capability, a skin time of 5–10 minutes at 20°C and a service temperature of -40°C to +200°C. It is not for perimeter pointing of uPVC or for use next to double glazed unit edge seals.
Everbuild 200 Contractors is a cost-effective acetoxy cure silicone with anti-fungal protection. It suits baths, showers, basins, aluminium and metal sealing, worktops and laminates, and fixing PVCu trims and panels. The TDS gives 12.5% movement capability, a joint width of 4–25 mm, and a yield of about 12 linear metres of a 7 x 7 mm fillet.
Aro-Seal 1162 is Ureka’s own neutral oxime cure silicone for perimeter sealing of wood, aluminium and PVCu frames and for weather sealing infill panels. It contains additional uPVC adhesion promoters, conforms to EN 15651-1 F EXT-INT, and has a service range of -60°C to +160°C with 12.5% movement accommodation.
Soudal Mir-o-bond is a neutral, low modulus silicone adhesive that does not attack the back coating of mirrors. It is used for fixing mirrors to uneven surfaces, mirror walls and sealing joints between mirrors, and stays permanently elastic after cure.
Use these factors to narrow down the right grade before you buy.
Glass, glazed ceramic, aluminium and stainless steel accept most silicones. Plastics such as PVC, polycarbonate and acrylic, soft metals such as lead and brass, and natural stone need care: use a neutral cure grade and always check the TDS limitations. Porous surfaces such as concrete, masonry and timber may need a primer.
For expansion joints, facades and frames, choose a low modulus silicone sealant with a high movement capability. For glazing and gasket sealing, a mid modulus grade gives a tougher bead.
Every silicone sealant is water-resistant once cured, but only sanitary grades with anti-fungal agents keep wet joints clean. Use one in showers, kitchens, food areas and cold rooms.
Acetoxy silicones skin quickly and are ideal for fast turnaround. Neutral cure grades can be slightly slower but are safer on sensitive substrates. All silicone cures at roughly 1–2 mm per day, so deep joints need a backer rod.
On site, a manual gun and 310ml cartridges of silicone sealant suit most jobs. In a factory, a pneumatic gun speeds up long runs and gives a more consistent bead.
Silicone sealant cannot be painted. If the joint must be overpainted, use an MS polymer such as Aro-Seal 1101 Hybrid Polymer Sealant instead. See our guide to MS polymer adhesives.
| Sealant type | Best for | Strengths | Watch-outs |
|---|---|---|---|
| Neutral cure silicone | Mixed materials, frames, metals, masonry, plastics | Low odour, broad adhesion, kind to metals | Not paintable; check natural stone and PC/PMMA |
| Acetoxy silicone | Glass, ceramic, sanitary, aluminium | Fast skinning, crystal clear, cost-effective | Vinegar smell; not for lead, brass, natural stone or some plastics |
| Sanitary silicone | Bathrooms, kitchens, cold rooms | Anti-fungal, stays clean in wet areas | Not a structural adhesive |
| Silicone adhesive | Mirrors, panels on uneven surfaces | Holds components while staying elastic | Slower skin time; needs support while curing |
| MS polymer sealant | Paintable joints, bonding and sealing in one | Overpaintable, high grab, bonds many substrates | Not as UV and heat stable as silicone in glazing |
Choose Soudal Silirub 2 if… you need one premium neutral cure silicone sealant for glazing, frames and construction joints across glass, metal, plastic, masonry and wood.
Choose Soudal Silirub 2/S if… the joint is in a bathroom, kitchen, food area, container or cold store and must resist mould.
Choose Soudal Silirub 1 if… you want a clear silicone sealant for glazing, sanitary ware and kitchen joints on glass, ceramic and metal.
Choose Everbuild 225 if… you are glazing, sealing glass to aluminium or making industrial and gasket seals that see heat up to +200°C.
Choose Everbuild 200 Contractors if… you need a cost-effective anti-fungal acetoxy silicone for volume sanitary and trim work.
Choose Aro-Seal 1162 if… you are perimeter sealing wood, aluminium or PVCu windows and doors.
Choose Soudal Mir-o-bond if… you are fixing mirrors and need a silicone adhesive that will not damage the backing.
Choose Aro-Seal 1101 if… the joint must be painted, or you need to bond and seal in one step.
This is usually caused by dust, grease, moisture or old sealant residue, or by using acetoxy silicone on an incompatible plastic. Best fix: cut out, clean with a solvent cleaner such as Formoa SA Surface Activator/Cleaner, and reseal with neutral cure Soudal Silirub 2.
General-purpose silicone sealant lacks enough anti-fungal protection for constantly wet joints. Best fix: Soudal Silirub 2/S sanitary silicone.
A stiff sealant in a moving joint, a joint that is too thin, three-sided adhesion, or movement before cure will split the bead. Best fix: a low modulus silicone sealant such as Soudal Silirub 2, with a backer rod to give a width-to-depth ratio of about 2:1.
Acetoxy silicone can stain natural stone and attack soft metals. Best fix: a neutral cure grade (Silirub 2 or Aro-Seal 1162) after a compatibility test; for natural stone, contact us for a stone-specific grade.
Some silicones cause stress cracking on PC and PMMA. Best fix: contact our technical team for an alkoxy-type or MS polymer alternative and test first.
Very deep beads, cold or dry conditions, or out-of-date stock slow the cure. Best fix: fresh cartridges applied at +5°C or above, with joint depth limited to about half the width.
An uneven gun trigger or no tooling leaves a lumpy bead. Best fix: a Cox Easiflow HD manual gun, a clean 45° nozzle cut, masking tape and a tooling spatula.
Acetoxy silicone sealant can damage mirror backing. Best fix: Soudal Mir-o-bond silicone adhesive.
Follow these seven proven tips for a clean, long-lasting silicone sealant joint.
The right silicone sealant depends on the substrate, the joint movement and the environment. For most mixed-material glazing and construction joints, Soudal Silirub 2 is the safest choice. For wet and hygienic areas use Soudal Silirub 2/S, and for clear acetoxy glazing and sanitary work choose Soudal Silirub 1, Everbuild 225 or Everbuild 200 Contractors.
For window and door frames, Aro-Seal 1162 gives a neutral cure seal with uPVC adhesion promoters, and for mirrors use Soudal Mir-o-bond. Browse the full sealant range and adhesive guns, or contact our technical team for help with a specific joint.
For most trade jobs, a neutral cure, low modulus silicone sealant such as Soudal Silirub 2 is the best all-rounder, bonding primerless to glass, metals, plastics, masonry and wood.
Acetoxy silicone releases acetic acid as it cures, skins fast and suits glass and ceramic. Neutral cure silicone has a low odour and is safer on metals, masonry and plastics.
Soudal Silirub 1 and Everbuild 225 are clear acetoxy options for glazing and glass-to-metal sealing. For frames and mixed materials, use clear Silirub 2 or Aro-Seal 1162.
Some sealants can fix light trims, but for load-bearing bonds such as mirrors use a dedicated silicone adhesive like Soudal Mir-o-bond, or an MS polymer.
Yes. “Caulk” is simply another word for a gun-applied sealant; silicone caulk and silicone sealant refer to the same type of product.
Most silicones skin in 5–30 minutes and cure through at roughly 1–2 mm per 24 hours at 20°C and 65% humidity. Deeper beads take longer.
Use a sanitary grade with an anti-fungicidal agent, such as Soudal Silirub 2/S.
No. Silicone sealant is not overpaintable. If a joint needs painting, use an MS polymer sealant such as Aro-Seal 1101.
Use a neutral cure grade, such as Aro-Seal 1162 with its uPVC adhesion promoters, and always test first. Avoid acetoxy silicone on PVC, PE, PP and PTFE.
Cut out the old bead with a sharp blade, remove residue mechanically, then clean the surface with a solvent cleaner so the new sealant can bond.
Formoa Surface Activator is at the same time: a cleaner, degreaser and primer. Formoa Surface Activator will activate non porous surfaces, such as: plastics, coatings and metals for improved adhesion of sealants based on silicone, polyurethane and MS Polymers.
Everflex LMA 200 Contractors Silicone is a contractor’s grade acetoxy cure sealant that adheres to most smooth and non-porous materials. Ideal for aluminium sealing, sealing around baths, showers, basins and other sanitary ware as well as an adhesive for fixing PVCu trims, cladding and panels.
Premium grade, low modulus neutral cure, sanitary silicone. Contains a powerful anti-fungicidal agent. Very fast skinning time and final cure. Thick-bodied. Primerless adhesion on all sanitary materials, including plastics. Highly elastic. Resistant to UV, rain, snow, Food contact certificate available.
Everflex Contract 225 Industrial & Glazing Silicone is a mid modulus acetoxy cure silicone sealant that adheres to most smooth and non-porous substrates. Typically used for single glazing, draught-proofing and general industrial use. Contains a powerful anti-fungal compound to prevent mould growth to the sealant.
Soudal Mirror adhesive is a high-quality neutral, elastical low modulus single component adhesive / sealant based on special silicone polymers.
Soudal Silirub 1 is a 310ml clear, low-modulus acetoxy silicone sealant for glazing, sanitary, kitchen and general construction sealing. It is 100% silicone, anti-mould, weather-resistant and bonds many common materials without primer.
Soudal Silirub 2 is a premium quality low modulus neutral cure silicone sealant. Very fast skinning time and final cure. 100% silicone, no shrinkage. Thick-bodied. Excellent toolability. Primerless adhesion on all common construction materials (glass, plastics, masonry substrates, metals and wood). High movement capability. Resistant to UV, rain, snow . High and low temperature resistance.
Aro-Seal 1162 is a one component professional grade neutral oxime curing silicone sealant used for sealing and flexible jointing in many applications.
Cartridge Nozzle for use with Sealant and Adhesive cartridges. Use with 290ml, 300ml and 310ml cartridges
The Easiflow HD Cartridge Gun is a high quality, hand operated applicator gun for dispensing adhesives and sealants from cartridges.
Ureka Global Ltd
Unit 5 Decoypool Road
St Modwen Park
Newport
NP19 4RG
