Soudal Silirub A - High Quality Sanitary Grade Acetoxy Silicone

Health & Safety Recommendations

Take the usual labour hygiene into account and read the packaging label and Safety Data Sheet before use. Keep the work area well ventilated during application and throughout curing, particularly in bathrooms, kitchens and enclosed sanitary rooms where vapours can linger. Wear suitable gloves and eye protection, avoid prolonged skin contact, and wash off any splashes promptly with clean water.

Silirub A is an acetoxy cure silicone and will release a typical acetic smell during curing, so good airflow is important for comfort and safe use. Keep the product away from children and food preparation areas, and avoid eating, drinking or smoking while applying the sealant. Where old sealant is being removed, take care with blades and scrapers, and ensure the work area is kept tidy to avoid slips, especially in wet rooms.

Substrate Suitability

Soudal Silirub A is designed for sanitary, glazing and general sealing work where a permanently elastic, mould-resistant silicone joint is required. It adheres well to many traditional and common construction substrates used in wet areas, including glass, glazed ceramic tiles, porcelain, many coated metals, anodised aluminium, stainless steel and suitable timber details.

It is not suitable for PE, PP, PTFE (Teflon®), PVC or bituminous substrates, and adhesion to these surfaces should not be relied upon. Because of its acid nature, certain metals such as copper and lead can be affected, so these materials should be avoided. Silirub A is also not recommended for natural stones such as marble and granite due to potential staining, and for these applications Soudal Fix ALL Flexi should be used instead.

Direct contact with the secondary seal of insulating glass units and the PVB film of safety glass must be avoided. A small adhesion and compatibility test is strongly recommended on every substrate, particularly when working with unusual coatings, painted surfaces, plastics, or where the joint will be regularly cleaned with chemicals.

Surface Preparation

The surface must be rigid, clean, dry and free from dust, grease, soap residue and loose contamination. In sanitary areas, the most common cause of early joint failure is poor preparation, especially where old silicone residue, limescale or cleaning-product build-up remains on the joint edges. Remove all existing sealant fully and clean the joint faces thoroughly before re-sealing.

If required, non-porous substrates can be cleaned and degreased using Soudal Cleaner & Degreaser, allowing the surface to dry fully before application. Porous substrates should be primed with Soudal Primer 150 where appropriate to support reliable adhesion, particularly on absorbent or inconsistent surfaces. Any primer should be applied neatly only to the bonding faces and allowed to dry as instructed before the sealant is installed.

Before gunning, mask both sides of the joint with suitable tape to keep the bead clean and sharp, especially around baths, shower trays, basins and tiled junctions. If a backer rod is needed to control joint depth, fit a suitable closed-cell backing material so the sealant bonds to two sides only, not three, helping the joint remain flexible and reducing stress.

Application Method

Apply Silirub A using a standard caulking gun. Cut the nozzle to suit the joint width and gun an even, continuous bead, ensuring the sealant is pushed firmly into the joint and makes full contact with both sides. Work steadily and avoid stretching the bead, as thin areas can lead to weak points and early failure.

Tool the joint immediately before skinning, shaping it to a smooth, slightly concave profile that sheds water and resists dirt pick-up. Finishing can be carried out using a suitable finishing tool with a light soapy solution, but care is essential. The joint edges must not be contaminated with the soapy solution, as this can reduce adhesion and cause edge lifting, so only the finishing tool should be dipped, not the surrounding surfaces.

Avoid applying finishing solutions in full sunlight or on hot surfaces, as they can dry too quickly and interfere with neat tooling. Once tooled, remove masking tape straight away while the sealant is still wet, then leave the joint undisturbed to cure. In bathrooms and kitchens, keeping the area dry and well ventilated during early curing will support a cleaner finish and stronger long-term performance.

Joint Dimensions

Silirub A is suitable for joints with a minimum width of 5mm and a maximum width of 30mm, with a minimum depth of 5mm. As a general rule for sealing jobs, the joint width should be around 2x the joint depth to maintain flexibility and support movement capability.

Where deeper joints are present, use a suitable PE backer rod to control depth and prevent 3-point adhesion, improving the durability of the seal.

Coverage

Coverage depends on joint width and depth, and the number of metres achievable per cartridge will vary significantly between fine sanitary beads and larger construction joints. For help calculating, use our online Sealant Estimate Calculator, selecting the correct joint dimensions to estimate the number of cartridges required for the job.

As a practical guide, sanitary joints are often small in section but can be long in run, so planning bead size carefully helps avoid waste while still maintaining a durable watertight seal.

Curing Time

Silirub A has a skin formation time of approximately 7 minutes, so tooling should be completed promptly after application. Curing is moisture driven and typically progresses at around 2mm per 24h, so deeper joints will take longer to cure through. Temperature, ventilation and humidity all influence cure speed, and cold or dry conditions can slow curing noticeably.

The sealant should be protected from water exposure during early curing, especially in showers and around baths. Where possible, keep the joint dry until a reliable cure has developed through the full depth, as early wetting can affect appearance and performance. Skinning time and curing speed may vary depending on the substrate type, site moisture levels and ambient conditions.

Cleaning

Clean excess sealant immediately after application. Uncured Silirub A can be removed from tools and nearby surfaces using Soudal Surface Cleaner or Soudal Swipex Wipes, before the sealant skins. Once cured, silicone can only be removed mechanically, and residues can be softened using Soudal Silicone Remover Gel or Soudal Sealant Remover Spray to assist removal where needed.

When removing cured silicone, take care not to scratch tiles, glass, acrylic baths or enamel surfaces, and always test removers on an inconspicuous area first. After removal, surfaces should be re-cleaned and degreased before reapplication to ensure adhesion is not compromised by invisible residues.

Limitations

Silirub A is a sanitary grade sealant with mould resistance, but it is not a substitute for regular cleaning of the joint. Excessive contamination, deposits and soap residues can stimulate fungal development, so joints should be kept clean and rinsed regularly, especially in high-use showers. Do not use in applications where continuous water immersion is possible, and for aquarium bonding Silirub AQ must be used instead.

Do not use Silirub A on polycarbonate and use Silirub PC where polycarbonate sealing is required. Avoid natural stones such as marble and granite due to staining risk, and use Soudal Fix ALL Flexi for those substrates. Because it is acetoxy and acidic, avoid sensitive metals such as copper and lead, and do not allow direct contact with insulating glass secondary seals or the PVB film of laminated safety glass.

A total absence of UV can cause colour change, and in dark or acidic environments a white sealant can slightly yellow. Under sunlight it will typically return towards its original colour. If different reactive joint sealants are being used in the same area, ensure the first sealant is completely hardened before applying the next one to avoid curing and compatibility issues.

Other Information

Silirub A conforms to LEED requirements for Low-Emitting Materials: Adhesives and Sealants under SCAQMD rule 1168, and complies with USGBC LEED 2009 Credit 4.1 concerning VOC content. This can be useful for projects where low-emission materials are specified for indoor air quality and compliance.

Apply only within the recommended application temperature range of +5°C to +35°C, and avoid sealing when surfaces are cold, damp or contaminated, as this can reduce adhesion and lead to premature failure. For the best long-term finish in bathrooms, kitchens and sanitary rooms, correct joint design, proper cleaning, controlled tooling and adequate curing time are as important as the sealant itself, and following these steps will help achieve a neat, watertight and durable silicone joint.

Q) What is Soudal Silirub A and what is it designed for?

A) Soudal Silirub A is a sanitary grade acetoxy silicone sealant made for watertight, permanently elastic sealing where joints are exposed to moisture, cleaning, and regular temperature change. It is commonly used around baths, shower trays, basins, kitchen sinks and tiled junctions, and it also suits many glazing and general sealing details. The formulation includes S1 fungicide to help resist black mould growth in warm, humid rooms. Once cured it stays flexible and can accommodate movement up to ±25%, helping the seal remain intact as fittings and building materials expand and contract during normal use.

Q) Where is Soudal Silirub A most commonly used in bathrooms?

A) Soudal Silirub A is ideal for sealing the perimeter of baths, shower trays, shower screens, wall tiles, corner joints and sink edges where water regularly runs, splashes or sits. The aim is to stop moisture tracking behind tiles and sanitary ware, which can lead to hidden damp, staining and mould. Because it skins quickly and tools smoothly, it helps produce a neat, hygienic bead that is easier to keep clean. For best performance, the joint must be properly prepared and fully cured before use. Keeping the area dry during early curing is important, especially on shower tray and bath edges.

Q) Can Soudal Silirub A be used in kitchens as well as bathrooms?

A) Yes, Soudal Silirub A is well suited to kitchens because it forms a watertight, flexible seal that copes with daily cleaning and frequent wetting. It is typically used around sinks, worktop upstands, tiled splashbacks, and junctions where steam and splashes are common. The mould resistance helps joints stay cleaner looking for longer, provided the bead is applied to clean, dry surfaces and the joint is maintained sensibly. In kitchens, grease films and detergent residues can reduce adhesion if surfaces are not properly degreased, so preparation matters. Once cured, the seal is resistant to UV and weathering, which also supports bright areas near windows.

Q) What substrates does Soudal Silirub A bond to without primer?

A) Soudal Silirub A offers strong primerless adhesion to many typical sanitary and construction substrates, especially non porous surfaces. Common examples include glass, glazed ceramic tiles, porcelain, enamelled surfaces, anodised aluminium, stainless steel, and many coated metals used in trims and frames. It can also be used on suitable timber details where a flexible, weather resistant seal is required. Adhesion always depends on surface condition, so remove soap residues, limescale, oils, and old silicone completely. If you are working on unusual coatings, painted finishes, or unknown materials, it is sensible to do a small test bead first to confirm bond quality and finishing behaviour.

Q) Which materials should be avoided with Soudal Silirub A?

A) Soudal Silirub A is not suitable for PE, PP, PTFE, PVC or bituminous substrates because reliable adhesion cannot be expected. As an acetoxy silicone, it is also best avoided on sensitive metals such as copper and lead, which can be affected by acidic cure. It is not recommended for natural stone like marble or granite due to staining risk, so a different sealant type is typically chosen for stone. Direct contact with the secondary seal of insulating glass units and the PVB film in laminated safety glass must be avoided. If the job involves specialist plastics or glazing details, carry out a compatibility check before committing.

Q) How does Soudal Silirub A resist mould and black staining?

A) Soudal Silirub A contains S1 fungicide to help resist mould growth, which is particularly important in warm, humid rooms where condensation and soap residues can feed fungal development. The mould resistance works best when the bead is applied properly and the joint is kept clean. If a bathroom joint is constantly contaminated with limescale, shampoo films, or trapped dirt, even the best sanitary silicone can eventually discolour. Good ventilation and regular cleaning helps, and the bead shape matters too. A smooth, slightly concave joint that sheds water and avoids ledges is easier to maintain and less likely to trap residue that encourages mould.

Q) How flexible is Soudal Silirub A once cured?

A) Once cured, Soudal Silirub A remains permanently elastic and is designed to accommodate joint movement up to ±25%. This matters in wet areas because baths, trays and frames can move slightly under load, and tiles and substrates expand and contract with temperature and moisture cycles. A flexible sealant helps prevent cracking and edge separation that can allow water ingress. Movement capability is also linked to correct joint design. If the bead is too thin, it can tear at the edges. If it is too deep, it can restrict movement and cure more slowly. Using a backer rod where needed helps maintain a durable, flexible joint.

Q) How quickly does Soudal Silirub A skin and how fast does it cure?

A) Soudal Silirub A has fast skin formation, typically around 7 minutes, so tooling should be done promptly after gunning the bead. Curing is moisture driven and progresses at roughly 2mm per 24 hours, so deeper joints take longer to cure through. Temperature, humidity and airflow all affect curing, and cold or very dry conditions can slow it. In bathrooms, avoid using the shower or soaking the joint until a reliable cure has developed through the full depth, not just on the surface. Good ventilation helps curing and reduces lingering acetoxy odour, especially in smaller rooms and enclosed shower areas.

Q) What joint sizes suit Soudal Silirub A best?

A) Soudal Silirub A is suitable for joints with a minimum width of 5mm and a maximum width of 30mm, with a minimum depth of 5mm. For good movement behaviour, joint proportions matter. A common rule is to keep the joint width around twice the joint depth, which helps the seal remain flexible and reduces stress. Very deep joints should be controlled with a suitable backer rod so the sealant bonds to two sides only, not three. This reduces the chance of splitting and improves elasticity. In sanitary work, consistent joint size also improves appearance and makes cleaning easier over the long term.

Q) How should surfaces be prepared before applying Soudal Silirub A?

A) Preparation is the biggest factor in long term performance. Joint edges must be rigid, clean, dry and free from grease, soap residue, limescale and dust. Remove all old silicone completely, including invisible smears, because new silicone will not bond reliably to cured silicone. In bathrooms, detergent build up and mould stains must be cleaned off, then the area should be dried thoroughly before sealing. Degreasing non porous surfaces is particularly important around kitchen sinks and worktops. Masking tape helps create clean edges on tiles and sanitary ware. If a backer rod is needed, fit it before gunning so depth is controlled and the bead finishes neatly.

Q) What is the best way to apply Soudal Silirub A for a watertight seal?

A) Cut the nozzle to match the joint width and gun a continuous bead, pushing the sealant firmly into the joint so it wets both sides fully. Avoid stretching the bead thin, as thin sections can tear and allow leaks. Tool immediately before skinning, shaping a smooth, slightly concave profile that sheds water and avoids ledges that trap dirt. If you use a finishing tool with a light soapy solution, keep the solution off the bonding edges because contamination can reduce adhesion and cause edge lifting. Remove masking tape straight after tooling while the sealant is still wet. Leave the joint undisturbed to cure fully before exposing it to water.

Q) Does Soudal Silirub A need a primer on porous or difficult backgrounds?

A) On many common non porous sanitary substrates, Soudal Silirub A is designed to adhere without primer. However, porous or inconsistent surfaces can sometimes benefit from priming to improve reliability, especially where absorbency varies or the surface is dusty. If you are sealing to porous materials, repaired plaster, or timber details that are not fully sealed, a suitable primer can stabilise the bonding face and improve wetting out. The key is that priming should not be used to compensate for poor preparation. Remove loose material and contamination first, then use primer only where it is genuinely required. If there is any doubt, test a small section and check adhesion after curing.

Q) Can Soudal Silirub A be painted over after curing?

A) Silicone sealants are generally not paintable in a reliable way, and Soudal Silirub A is best treated as a finished surface. Many paints will not bond properly to cured silicone, and even if a paint film initially holds, movement and cleaning can cause cracking or peeling. If you need a sealant that will be painted, a paintable acrylic or hybrid sealant is usually the correct approach. For Silirub A applications, focus on producing a neat bead with clean edges and a uniform profile so it looks finished without paint. Choosing the right colour for the background helps. Masking and careful tooling are the simplest ways to achieve a crisp decorative result.

Q) Is Soudal Silirub A suitable for glazing and glass to glass joints?

A) Soudal Silirub A bonds strongly to glass and can be used for many glazing and glass to glass sealing details where a neat, elastic joint is required. It is also useful on anodised aluminium and stainless steel trims often found in glazing and fit out work. However, it must not be used where it could come into direct contact with the secondary seal of insulating glass units or the PVB interlayer in laminated safety glass, as compatibility issues can occur. If the glazing detail is part of a system, always follow the glass and frame manufacturer guidance. For internal glazing trims and similar sealing, it is a practical option when used with correct joint design.

Q) Can Soudal Silirub A be used outdoors and how does it handle UV and weathering?

A) Yes, Soudal Silirub A offers excellent resistance to weathering and UV, which supports use in sheltered outdoor joints and perimeter sealing details where a durable, elastic seal is required. It is also resistant to temperature extremes, so it copes well with seasonal movement and sunlight exposure. Outdoor suitability still depends on joint design and substrate compatibility. Surfaces must be clean and dry, and the bead must be allowed to cure without early rain wash or freezing conditions. For exposed locations, make sure the joint profile sheds water rather than holding it. If a joint is likely to be constantly saturated or immersed, a different product choice may be needed.

Q) How resistant is Soudal Silirub A to cleaning chemicals and everyday detergents?

A) Once cured, Soudal Silirub A has good resistance to many household cleaning products, which is important for sanitary joints that are scrubbed and rinsed regularly. That said, harsh cleaners, strong acids, and abrasive powders can wear the surface over time and encourage dirt retention, which can affect appearance. Mould resistance performs best when joints are kept clean and rinsed, rather than left coated in soap film. If you regularly use strong descalers, test them on an inconspicuous area first and rinse thoroughly after use. A smooth, well tooled bead also improves chemical run off and reduces places where residues can sit and discolour the joint.

Q) What is the recommended application temperature range for Soudal Silirub A?

A) Soudal Silirub A should be applied within the recommended range of 5°C to 35°C for consistent gunning, tooling and curing. Cold surfaces slow curing and can cause condensation, which reduces adhesion, especially on non porous tiles and metals. Very hot surfaces can shorten tooling time because skinning happens faster. In bathrooms, warm the room slightly and ventilate well so curing proceeds steadily and the acetoxy smell disperses. Avoid sealing onto damp surfaces, and do not apply when rain or frost is likely before cure if you are working outside. Good temperature control, dry substrates, and airflow are the simplest ways to get a clean bead and reliable long term performance.

Q) How should Soudal Silirub A be cleaned up during application?

A) Clean up is easiest while the sealant is still uncured. Excess Soudal Silirub A can be wiped away immediately using suitable wipes or a surface cleaner intended for fresh sealant residues, taking care to avoid smearing onto porous materials. On tiles and glass, wipe lightly and change cloths often to avoid spreading a thin silicone film. Once the sealant skins, cleaning becomes harder and can spoil the bead edge, so work in manageable lengths and finish as you go. After curing, silicone can only be removed mechanically, so careful masking and prompt wipe down prevents time consuming clean-up later. Always keep cleaners off bonding edges during tooling, as contamination can affect adhesion.

Q) How do I remove and replace old silicone before applying Soudal Silirub A?

A) Old silicone must be removed fully because new silicone will not bond reliably to cured silicone. Cut out the bulk with a sharp blade, then remove the remaining film by careful scraping. A dedicated silicone remover gel or spray can help soften residues, especially on tiles and glass, but always test first and follow the remover instructions. After removal, clean and degrease the joint edges to remove invisible residues, then dry thoroughly. In bathrooms, also remove soap scum and limescale, as these can prevent adhesion. Once the surfaces are clean and dry, re-seal promptly so dust and moisture do not settle back into the joint before you gun the new bead.

Q) What are the key limitations and special cases for Soudal Silirub A?

A) Soudal Silirub A is not suitable for aquariums, where a dedicated aquarium silicone is required. It should not be used on polycarbonate, where a compatible product is needed, and it should be avoided on natural stone due to staining risk. Because it is acetoxy curing, avoid sensitive metals such as copper and lead. It is also not suitable for PE, PP, PTFE, PVC or bituminous substrates. Take care with glazing details, avoiding contact with insulating glass secondary seals and laminated glass PVB films. In very dirty or neglected wet areas, mould resistance will not compensate for poor hygiene, so joint cleanliness and ventilation still matter.

Q) Why can white silicone slightly yellow, and how do I minimise colour change?

A) In some conditions, white silicone can show slight yellowing, particularly in dark environments with little UV exposure, or where acidic or strongly coloured contaminants contact the joint. This is not usually a performance failure, but it can affect appearance. In areas with sunlight, the colour can often return closer to normal over time. To minimise discolouration, keep joints clean, rinse off strong cleaners, and avoid leaving dyes or hair products sitting against the bead. Correct tooling helps too, because a smooth surface is less likely to trap residue. If matching is critical, choose a colour that suits the installation and maintain consistent bead size, since thicker beads can appear different under certain lighting.

Q) How should Soudal Silirub A be stored and handled between jobs?

A) Store cartridges sealed and upright where practical, away from direct heat and frost, so the product remains consistent and easy to gun. Before use, bring the cartridge to a sensible working temperature, especially in winter, as cold silicone extrudes poorly and can lead to an uneven bead. Keep the nozzle capped between use to reduce curing in the tip, and if a nozzle does block, replace it rather than forcing poor flow. When transporting to site, protect cartridges from puncture and keep them clean so dust does not contaminate fresh beads. As with any sealant, use good ventilation during application, wear gloves, and keep blades and tools controlled when cutting out old sealant.

Technical Data Sheet

Declaration of Performance (DoP)

Safety Data Sheet