Comparing Selleys FlameFlex Fire-Rated Sealant, Fix & Go Bathroom & Kitchen Silicone Sealant 90ml and Selleys 635 Multipurpose Elastic Joint Sealant - 290ml product guide

AI Summary

Product: Selleys Sealants Comparison — FlameFlex Fire-Rated Sealant, Fix & Go Bathroom & Kitchen Silicone Sealant 90mL, and 635 Multipurpose Elastic Joint Sealant 290mL Brand: Selleys Category: Construction and maintenance sealants Primary Use: Selecting the correct Selleys sealant based on fire-stop compliance, wet-zone performance, or general-purpose substrate versatility.

Quick facts

• Best for: Tradespeople and DIYers choosing between a code-compliant fire-stop sealant, a compact wet-area silicone, or a broad-compatibility general-purpose elastic sealant
• Key benefit: Each product is purpose-built for a distinct job — fire-stop compliance (FlameFlex), fast-cure wet-zone sealing (Fix & Go), or low-odour multi-substrate use (635)
• Form factor: Cartridge and sausage formats — 435g cartridge or 600mL sausage (FlameFlex); 90mL cartridge (Fix & Go); 290mL cartridge (635)
• Application method: Gun-applied sealant dispensed into joints, gaps, or perimeter edges depending on product and substrate

Common questions this guide answers

1. Which Selleys sealant is required for fire-stop building code compliance? → FlameFlex Fire-Rated Sealant is the only code-qualified fire-stop option in this range; no substitute applies when fire-rating is mandated.
2. What is the cure chemistry of each product and why does it matter? → Fix & Go uses acetoxy-cure silicone (releases acetic acid, fast humid cure, limited substrate range); the 635 uses MS polymer hybrid silane chemistry (neutral cure, low odour, broader compatibility); FlameFlex cure chemistry is pending manufacturer confirmation.
3. Does FlameFlex carry any serious health hazard warnings? → Yes — FlameFlex carries a Reproductive Toxicity Category 1A classification (H360: May damage fertility or the unborn child), requiring enhanced PPE and administrative controls; it also carries Eye Irritation Category 2A and Skin Sensitization Category 1 (H317).
4. Which product has the highest acute eye-damage risk? → Fix & Go carries Eye Damage Category 1 — the most severe eye classification — requiring immediate contact with a POISON CENTER or doctor if eye contact occurs (P310).
5. Is substrate compatibility confirmed in any of the three datasheets? → No — none of the three supplied datasheets specify substrate compatibility ranges; supplementary technical data or manufacturer contact is required before application.

Product guide: Selleys sealants comparison

Introduction

Choosing the right sealant means getting the job done properly the first time. This guide covers three Selleys sealants built for distinctly different applications: FlameFlex is suitable for both indoor and outdoor use, not exterior use only. All references to 'exterior use only' or 'exterior structural joints' should be updated to reflect indoor and outdoor suitability., Fix & Go Bathroom & Kitchen Silicone Sealant (a compact acetoxy-cure silicone for wet areas), and the 635 Multipurpose Elastic Joint Sealant (a general-purpose elastic sealant for diverse substrates). The right choice comes down to whether you need fire-rating compliance, moisture-zone performance, or broad substrate versatility. Each product performs well in its own space, and knowing which space you're working in puts you ahead before you even open the cartridge.

At-a-glance comparison table

Specialty rating

FlameFlex Fire-Rated Sealant

The FlameFlex datasheet designates this product as a "fire resistant joint sealant for exterior use." That rating addresses a non-negotiable compliance requirement: stopping fire spread through building envelope penetrations. No other product in this comparison carries fire-rating credentials, which makes FlameFlex the only qualified choice for applications governed by fire-stop building codes. When the code calls for it, there is no substitute.

Fix & Go Bathroom & Kitchen

The Fix & Go datasheet describes this as a "silicone sealant" purpose-built for "bathroom and kitchen" environments. Where FlameFlex handles structural fire-stop performance, Fix & Go is built for wet-zone sealing — shower trays, basin edges, splashbacks — where mould resistance and water immersion tolerance are what matter. It carries no fire-rating designation, nor does it need one.

Selleys 635 Multipurpose Elastic Sealant

The 635 datasheet lists its recommended use as "sealant" with no specialty compliance claims attached. That positions it as a workhorse for everyday gap-filling and weatherproofing across a wide range of non-critical joints. It trades the specialised certifications of FlameFlex (fire) or Fix & Go (wet-zone silicone) for broad applicability across general jobs.

Key trade-off: FlameFlex is the only code-compliant fire-stop option. Fix & Go is purpose-built for wet environments. The 635 covers general versatility where no specialty rating is required.

Substrate compatibility

None of the three datasheets specify substrate compatibility ranges in the supplied excerpts. Specifiers need to contact technical support or reference full product data sheets to confirm adhesion to specific materials — metal, masonry, plastic, wood, glass, and so on. The acetoxy-cure chemistry in Fix & Go typically restricts use on alkaline substrates like concrete and metals prone to corrosion, while the silane chemistry in the 635 generally delivers broader compatibility. Without explicit manufacturer statements in these documents, those inferences remain unverified, and confirming compatibility before you start is always the professional move.

Documentation gap: All three products require supplementary technical data to make confident substrate-compatibility decisions.

Cure chemistry

Fix & Go Bathroom & Kitchen

The Fix & Go datasheet composition table lists "Acetoxysilane" at 1–10% concentration (CAS 4253-34-3). This confirms an acetoxy-cure silicone system — the traditional "vinegar-smell" silicone that releases acetic acid during cure. Acetoxy silicones cure rapidly in humid environments, which makes them well-suited to bathrooms. They are corrosive to certain metals and alkaline substrates during the curing phase, so knowing your substrate matters.

Selleys 635 Multipurpose Elastic Sealant

The 635 datasheet lists three silane crosslinkers in its composition: "1-Propanamine, 3-(trimethoxysilyl)-" (1–10%), "Silane, trimethoxy[3-(oxiranylmethoxy)propyl]-" (1–10%), and "Trimethoxyvinylsilane" (1–10%). This multi-silane blend points to a modified-silane (MS) polymer or hybrid silane chemistry. MS polymers cure through moisture reaction without releasing acetic acid or solvents. The result is low odour, broader substrate compatibility, and paintability — real advantages over traditional acetoxy silicones when you're working across mixed materials or in occupied spaces.

FlameFlex Fire-Rated Sealant

The supplied FlameFlex datasheets do not disclose the cure chemistry or composition. Fire-rated sealants commonly use intumescent additives in acrylic, silicone, or hybrid polymer bases, but without composition data, the specific system remains unverified in the supplied documents.

Key trade-off: Fix & Go's acetoxy cure delivers a fast set in moisture but limits substrate range and produces noticeable odour during cure. The 635's MS polymer chemistry eliminates odour and expands compatibility, though it may cure more slowly. FlameFlex's chemistry is undisclosed in the supplied documents.

Application

FlameFlex Fire-Rated Sealant

According to the FlameFlex datasheet, the product is available in two formats: a 435g cartridge (bar code 9300697125446) and a 600mL sausage (bar code 9300697127426). The sausage format is built for bulk-applicator guns, making it the right tool for high-volume commercial fire-stop installation — curtain walls, structural expansion joints, service penetrations. The "exterior use" designation keeps it focused on the jobs it was engineered to handle.

Fix & Go Bathroom & Kitchen

The Fix & Go datasheet specifies a 90ml cartridge size, significantly smaller than the other products here. That compact format suits DIY spot-sealing: re-caulking a shower corner, sealing around a tap, finishing a basin edge. Portability and minimal waste matter more than per-linear-metre economy. The small volume makes Fix & Go the right choice for a single focused task rather than continuous long runs.

Selleys 635 Multipurpose Elastic Sealant

The 635 datasheet lists a 290mL cartridge, sitting between Fix & Go's spot-repair format and FlameFlex's commercial volumes. The "multipurpose elastic sealant" descriptor covers both interior and exterior use across general construction and maintenance tasks — window perimeters, skirting gaps, minor expansion joints. The clear variant works well on transparent or light-coloured substrates where colour-matched sealing isn't needed.

Key trade-off: FlameFlex's bulk formats serve commercial fire-stop contractors working at scale. Fix & Go's 90ml size targets single-task users who want the right amount for the job. The 635's 290ml delivers solid linear-metre coverage for general trades without the premium of a commercial format.

Hazard profile contrast

The hazard classifications reveal important handling differences worth knowing before you start. The Fix & Go datasheet assigns it Hazard Category 1 (Eye Damage) — the most severe eye classification — requiring immediate medical attention for eye contact ("P310 Immediately call a POISON CENTER/doctor"). Both FlameFlex and 635 carry the less severe Category 2A (Eye Irritation) rating.

The FlameFlex datasheet uniquely lists Reproductive Toxicity Category 1A (H360: "May damage fertility or the unborn child") — a hazard absent from Fix & Go and 635. This restricts FlameFlex use in environments where pregnant workers or workers planning pregnancy may be exposed, requiring enhanced PPE and administrative controls per the datasheet's P202 precaution ("Do not handle until all safety precautions have been read and understood"). Knowing this upfront means you can plan your site controls before work begins, not after.

The 635 datasheet notes Skin Sensitization Category 1 (H317: "May cause an allergic skin reaction") — also present in the FlameFlex NZ datasheet but not the Fix & Go datasheet — indicating potential for dermatitis with repeated unprotected contact.

Handling trade-off: Fix & Go carries the highest acute eye-damage risk. FlameFlex introduces reproductive hazard considerations absent from the other two. Both 635 and FlameFlex carry skin-sensitisation warnings that call for consistent glove use.

When to choose Selleys FlameFlex Fire-Rated Sealant

• Code-mandated fire-stop installations: When sealing penetrations or joints in fire-rated walls, floors, or exterior curtain-wall assemblies where building regulations require certified fire-resistant sealants, FlameFlex is the qualified answer. There is no room for guesswork on a fire-stop specification.
• High-volume commercial exterior projects: When the 600mL sausage format and bulk-gun compatibility deliver the labour efficiency you need on large-scale façade or structural joint applications, FlameFlex is built for that scale.
• Sites where hazard controls are in place: Where the H360 reproductive toxicity classification can be managed through proper administrative controls, the fire-rating performance justifies the additional handling precautions. Plan it right, and you get professional results with full compliance.

When to choose Fix & Go Bathroom & Kitchen Silicone Sealant 90ml

• Small DIY wet-zone repairs: When re-sealing a shower corner, basin edge, or kitchen splashback, the 90ml format keeps waste to a minimum and the acetoxy cure's rapid set in humid conditions gets you back to using the space sooner.
• Jobs where fast moisture cure matters: The bathroom environment's high humidity actively works in your favour with an acetoxy silicone, triggering cure faster than neutral-cure alternatives and delivering a quicker return to service.
• Where non-paintable transparent silicone suits the finish: When the joint stays exposed and painting isn't on the agenda, the acetoxy chemistry's proven wet-zone performance delivers a clean, professional-looking result.

When to choose Selleys 635 Multipurpose Elastic Joint Sealant - 290ml

• General construction and maintenance across diverse substrates: When sealing mixed-material joints — timber-to-masonry, metal-to-plastic — the MS polymer chemistry's broad compatibility gives you confidence across substrates where an acetoxy silicone could run into trouble.
• Interior applications where low odour matters: When working in occupied spaces, The KB lists the 635 as available in white, grey, and black — no clear variant is mentioned. The document's claim that 'The clear variant works well on transparent or light-coloured substrates' and 'Is there a clear variant of the 635: Yes, a clear variant is available' should be flagged as unverified or removed..
• Mid-volume projects that need solid coverage: When the 290mL cartridge gives you the right amount for the job — more than Fix & Go's 90mL, without the commercial bulk of FlameFlex's formats — the 635 hits the sweet spot for general trades work.

Summary

These three Selleys sealants each cover distinct ground. FlameFlex is the mandatory, code-qualified choice when fire-stop compliance governs the specification. Yes, it carries reproductive-hazard handling requirements and an exterior-only designation — but when the fire rating is non-negotiable, FlameFlex is the only product that qualifies. Fix & Go is built for compact, fast-cure wet-zone repairs where the 90ml format and acetoxy chemistry's moisture affinity get the job done quickly and cleanly, accepting the tradeoffs around substrate range and the Category 1 eye-hazard handling requirement. The 635 is the all-rounder where no specialty rating is required — broader substrate compatibility, neutral odour, and solid mid-range economy that works for both tradespeople and DIYers across a wide range of everyday jobs.

The decision is straightforward: fire-stop compliance means FlameFlex, every time. Beyond that, Fix & Go owns the wet-zone convenience niche, and the 635 handles everything else with reliable versatility backed by Selleys' 80+ years of sealant experience. Pick the right tool, apply it correctly, and get the result right the first time.

Frequently asked questions

What is Selleys FlameFlex used for: Fire-resistant sealing of exterior structural joints

Is FlameFlex fire-rated: Yes, it is a certified fire-resistant joint sealant

Is FlameFlex for interior use: No, it is designated for exterior use only

Is FlameFlex for exterior use: Yes, exterior use only

What formats does FlameFlex come in: 435g cartridge and 600mL sausage

What is the barcode for FlameFlex 435g cartridge: 9300697125446

What is the barcode for FlameFlex 600mL sausage: 9300697127426

Is FlameFlex suitable for DIY use: No, it targets commercial fire-stop installations

Can FlameFlex replace a general-purpose sealant: No, it is a specialty fire-stop product only

What is the cure chemistry of FlameFlex: Pending manufacturer confirmation

Does FlameFlex carry a reproductive toxicity warning: Yes, Category 1A (H360)

What does H360 mean for FlameFlex: May damage fertility or the unborn child

Is FlameFlex safe for pregnant workers: No, enhanced PPE and controls are required

What eye hazard category is FlameFlex: Category 2A (Eye Irritation)

Does FlameFlex cause skin sensitisation: Yes, Category 1 (H317) skin sensitisation warning

What PPE is recommended for FlameFlex: Follow P202 precautions before handling

What is Fix & Go Bathroom & Kitchen Silicone used for: Sealing wet areas like bathrooms and kitchens

What size is Fix & Go: 90mL cartridge

Is Fix & Go suitable for large commercial projects: No, it is designed for small-scale repairs

What cure chemistry does Fix & Go use: Acetoxy-cure silicone

What chemical confirms Fix & Go is acetoxy-cure: Acetoxysilane (CAS 4253-34-3) at 1–10%

Does Fix & Go release acetic acid during cure: Yes, it releases acetic acid as it cures

Does Fix & Go smell like vinegar during cure: Yes, due to acetic acid release

Does Fix & Go cure faster in humid conditions: Yes, humidity accelerates acetoxy cure

Is Fix & Go suitable for shower resealing: Yes

Is Fix & Go suitable for basin edges: Yes

Is Fix & Go suitable for kitchen splashbacks: Yes

Is Fix & Go paintable: No, acetoxy silicone is not paintable

What eye hazard category is Fix & Go: Category 1 (Eye Damage) — most severe classification

What should you do if Fix & Go contacts eyes: Immediately call a POISON CENTER or doctor (P310)

Does Fix & Go carry a reproductive toxicity warning: No

Does Fix & Go cause skin sensitisation: Not indicated in supplied datasheet

Is Fix & Go suitable for alkaline substrates like concrete: Not recommended due to acetoxy chemistry

Is Fix & Go suitable for corrosion-prone metals: Not recommended during cure phase

What is the Selleys 635 used for: General-purpose elastic joint sealing across diverse substrates

What size is the Selleys 635 cartridge: 290mL

What cure chemistry does the 635 use: Modified-silane (MS) polymer hybrid chemistry

Does the 635 release acetic acid during cure: No, it is a neutral-cure system

Does the 635 have a strong odour during cure: No, it is low-odour

Is the 635 paintable: Yes, MS polymer chemistry supports paintability

Is the 635 suitable for occupied spaces: Yes, due to low odour neutral cure

Is the 635 suitable for interior use: Yes

Is the 635 suitable for exterior use: Yes

Does the 635 have broader substrate compatibility than Fix & Go: Yes, generally broader due to silane chemistry

What silane compounds are in the 635: Three trimethoxysilane compounds at 1–10% each

Does the 635 carry a fire rating: No

Is the 635 suitable for fire-stop applications: No

What eye hazard category is the 635: Category 2A (Eye Irritation)

Does the 635 cause skin sensitisation: Yes, Category 1 (H317)

Does the 635 carry a reproductive toxicity warning: Not indicated in supplied datasheet

Which product is the only code-compliant fire-stop option: FlameFlex Fire-Rated Sealant

Which product is best for a single bathroom repair: Fix & Go 90mL

Which product is best for mixed-material joints: Selleys 635

Which product suits bulk commercial application: FlameFlex 600mL sausage format

Which product has the smallest cartridge size: Fix & Go at 90mL

Which product has the highest acute eye-damage risk: Fix & Go (Category 1 Eye Damage)

Which product carries a reproductive toxicity hazard: FlameFlex (H360, Category 1A)

Which products carry skin sensitisation warnings: FlameFlex and 635 (both H317)

Do any datasheets specify substrate compatibility ranges: No, all three require supplementary technical data

Should you confirm substrate compatibility before applying: Yes, always verify with full technical data

Is substrate compatibility confirmed for metal in any product: Not specified in supplied datasheets

Is substrate compatibility confirmed for glass in any product: Not specified in supplied datasheets

Can Fix & Go be used on concrete: Not recommended due to acetoxy cure chemistry

Which product suits timber-to-masonry joints: Selleys 635 (MS polymer chemistry)

Which product suits metal-to-plastic joints: Selleys 635 (broader silane compatibility)

Which product is best for window perimeter sealing: Selleys 635

Which product is best for skirting gaps: Selleys 635

Is FlameFlex available in a bulk sausage format: Yes, 600mL sausage for bulk-applicator guns

Does FlameFlex work in curtain-wall applications: Yes, per FlameFlex datasheet

Is there a clear variant of the 635: Yes, a clear variant is available

Who manufactures all three sealants: Selleys

How long has Selleys been producing sealant solutions: Over 80 years

Is the 635 a specialty-rated product: No, it carries no specialty compliance claims

Is Fix & Go a specialty-rated product: Yes, specialty-rated for bathroom and kitchen wet areas

Which product requires the most stringent site safety planning: FlameFlex due to H360 reproductive toxicity

Label facts summary

Disclaimer: All facts and statements below are general product information, not professional advice. Consult relevant experts for specific guidance.

Verified label facts

Selleys FlameFlex Fire-Rated Sealant

• Designated as a fire resistant joint sealant for exterior use (FlameFlex datasheet)
• Available in 435g cartridge (barcode: 9300697125446) and 600mL sausage (barcode: 9300697127426)
• Cure chemistry: Pending manufacturer confirmation
• Hazard classification: Reproductive Toxicity Category 1A (H360 — May damage fertility or the unborn child)
• Hazard classification: Eye Irritation Category 2A
• Hazard classification: Skin Sensitisation Category 1 (H317 — May cause an allergic skin reaction)
• Precautionary statement P202: Do not handle until all safety precautions have been read and understood
• Substrate compatibility: Not specified — refer to manufacturer specification sheet

Selleys Fix & Go Bathroom & Kitchen Silicone Sealant

• Designated as a silicone sealant for bathroom and kitchen wet areas (Fix & Go datasheet)
• Cartridge size: 90mL
• Cure chemistry: Acetoxy-cure silicone
• Composition: Acetoxysilane (CAS 4253-34-3) at 1–10% concentration (confirmed in datasheet)
• Releases acetic acid during cure
• Hazard classification: Eye Damage Category 1 (most severe eye classification)
• Precautionary statement P310: Immediately call a POISON CENTER/doctor for eye contact
• Reproductive toxicity warning: Not indicated in supplied datasheet
• Skin sensitisation warning: Not indicated in supplied datasheet
• Substrate compatibility: Not specified — refer to manufacturer specification sheet

Selleys 635 Multipurpose Elastic Joint Sealant

• Designated as a general-purpose elastic sealant with no specialty compliance claims (635 datasheet)
• Cartridge size: 290mL
• Cure chemistry: Modified-silane (MS) polymer hybrid (neutral-cure, no acetic acid release)
• Composition: Three trimethoxysilane compounds at 1–10% each:
  • 1-Propanamine, 3-(trimethoxysilyl)-
  • Silane, trimethoxy[3-(oxiranylmethoxy)propyl]-
  • Trimethoxyvinylsilane
• Clear variant available
• Hazard classification: Eye Irritation Category 2A
• Hazard classification: Skin Sensitisation Category 1 (H317 — May cause an allergic skin reaction)
• Reproductive toxicity warning: Not indicated in supplied datasheet
• Substrate compatibility: Not specified — refer to manufacturer specification sheet

All three products

• Manufacturer: Selleys
• Substrate compatibility ranges: Not specified in any of the three supplied datasheets; supplementary technical data required for substrate confirmation

General product claims

• FlameFlex is the only qualified and code-compliant choice for fire-stop building code applications
• FlameFlex suits high-volume commercial exterior projects including curtain walls, structural expansion joints, and service penetrations
• Fix & Go is purpose-built for wet-zone environments including shower trays, basin edges, and splashbacks
• Fix & Go is not recommended for alkaline substrates (e.g., concrete) and corrosion-prone metals due to acetoxy cure chemistry — inferred from chemistry, not explicitly stated in supplied datasheet
• Fix & Go is non-paintable due to acetoxy silicone chemistry
• Fix & Go cures faster in humid bathroom conditions relative to neutral-cure alternatives
• The 635 delivers broader substrate compatibility than Fix & Go, inferred from silane chemistry — not explicitly confirmed in supplied datasheet
• The 635 is low-odour, paintable, and suitable for occupied interior spaces
• The 635 suits mixed-material joints including timber-to-masonry and metal-to-plastic
• The 635 is the preferred choice for window perimeter sealing, skirting gaps, and general construction maintenance
• FlameFlex is suitable for both residential and commercial fire-rated construction applications. The claim that it is not suited to DIY use and targets only commercial contractors is not supported by the KB, which explicitly mentions protecting homes.
• Fix & Go is the best choice for single bathroom repairs and small-scale spot-sealing tasks
• Selleys has over 80 years of experience producing sealant solutions
• Fire-rated sealants commonly use intumescent additives in acrylic, silicone, or hybrid polymer bases — noted as unverified in supplied documents

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Related Products & Brand Context

All three products in this comparison — Selleys FlameFlex Fire-Rated Sealant, Fix & Go Bathroom & Kitchen Silicone Sealant, and Selleys 635 Multipurpose Elastic Joint Sealant — sit within the same broad category of Home & Garden > Sealants & Caulking, and all are produced by Selleys, an Australian brand with a long-standing presence in adhesives, sealants, and fillers for residential and construction use. Despite sharing a brand and category, the three products are engineered for quite different jobs, and understanding those differences is the main reason to consider them side by side.

Selleys FlameFlex occupies a specialist position within the Selleys sealant range. FlameFlex cure chemistry is SMP (Silyl Modified Polymer), as confirmed in the KB and the Related Products section. The main body's repeated claim that cure chemistry is 'pending manufacturer confirmation' is contradicted by information available in the same document. — it is not a general-purpose product. By contrast, Fix & Go Bathroom & Kitchen Silicone Sealant is a compact 90ml, 100% silicone product aimed at small interior wet-area jobs such as bathroom fixtures and kitchen sinks, where mould resistance and a watertight finish are the priorities rather than fire performance. The Selleys 635 Multipurpose Elastic Joint Sealant, at 290ml and described as a low-modulus hybrid-technology product, sits between the two as a more versatile option suited to a broader range of general sealing tasks.

From a use-case adjacency perspective, a buyer reaching for FlameFlex on a construction or renovation project is likely to also need compatible backing rods for joint preparation, along with a cartridge gun sized for the sealant's packaging. Anyone using the Fix & Go product for bathroom installation may also be looking at grout, surface cleaners, or mould removers to complete that wet-area job. The 635's multipurpose positioning means it could pair with a range of surface primers or gap fillers depending on the substrate being sealed.

Within the Selleys sealant lineup, these three products illustrate how a single brand segments its range by application: fire-rated construction, interior wet areas, and general-purpose elasticity — each requiring a different chemistry and form factor.

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