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Mapei Keraflex Maxi S1 is a high-performance, deformable cementitious adhesive classified as C2TE S1, specifically formulated for the installation of large-format porcelain and natural stone. This highly thixotropic formula prevents vertical slip on heavy wall panels and allows for a 15mm maximum application thickness to correct uneven substrates without pre-levelling.
Engineered with a high concentration of synthetic resins, it ensures superior membrane adhesion and prevents delamination when applied over Mapelastic waterproofing systems. The extended 30-minute open time and 60-minute adjustability window provide the precision required for complex commercial layouts, while its S1 deformability absorbs structural vibrations and thermal stresses on heated floors.
Frequently Asked Questions
What bed thickness can I achieve on uneven floors?
Up to 15 mm in a single pass on floors. This allows minor levelling while fixing large tiles, reducing separate prep steps and keeping schedules tight. Always verify coverage and compress ribs for solid support.
Does it slip on walls with heavy porcelain panels?
The adhesive is highly thixotropic and rated “T” (no vertical slip), allowing top-down setting without spacer pegs. Use back-buttering and correct notch size to maintain coverage and control.
When can I grout walls and floors?
Walls: 4–8 hours. Floors: ~24 hours, depending on tile size and conditions. Choose Keracolor FF/GG or Ultracolor Plus; for chemical resistance, specify Kerapoxy.
Is it suitable over waterproofing membranes?
Yes—apply over Mapelastic AquaDefense/Smart or Mapegum WPS once cured. Ensure full coverage (back-butter), especially for profiled backs and immersed areas.
What are the application temperature limits?
Apply between +5 °C and +35 °C. Service range is −30 °C to +90 °C. In hot/windy weather, reduce spread size and re-comb if a skin forms.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Large-format porcelain on walls | No vertical slip; extended adjustability for precise alignment | Tilers, Builders |
| Uneven screeds (floor) | Up to 15 mm bed reduces separate levelling steps | Tilers, Builders |
| Heated floors | S1 deformability manages thermal movement | Tilers, Builders |
| Over waterproofing membranes | Compatible system approach with Mapelastic membranes | Waterproofers, Tilers |
| Overlay on existing tiles | High adhesion to stable, properly prepared finishes | Tilers |
Applying Keraflex Maxi S1: Enhanced Protocols & Best Practices
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Mixing
Pour powder into clean water while mixing at low speed; rest 5 min and re-mix to a smooth paste.
Grey
5.6–6.0 L water per 20 kg (28–30%).
White
5.4–5.8 L water per 20 kg (27–29%).
Timing: Pot life >8 h at 23 °C (shorter in hot/dry/windy conditions).Pro Tip: Use a clean bucket and paddle; avoid over-watering which reduces strength. -
Trowelling & Coverage
Key in a contact coat, then comb fresh ribs with a suitable notch. Back-butter large or profiled tiles to achieve ≥95% contact (wet areas/immersed) and ≥80% minimum elsewhere.
Floors (uneven)
Use larger notch; up to 15 mm bed to correct minor irregularities.
Walls (heavy panels)
Exploit high thixotropy; set from top-down without spacers, checking plumb.
Timing: Open time >30 min; adjustability ~60 min at 23 °C.Pro Tip: If a skin forms, re-comb; do not wet the bed—water creates an anti-adhesive film. -
Curing, Grouting & Service
Protect fresh work from rain, frost, and strong sun. Honor movement joints and seal appropriately.
Grouting
Walls 4–8 h; floors ~24 h. Use Keracolor FF/GG, Ultracolor Plus, or Kerapoxy where chemical resistance is required.
Movement Joints
Seal with Mapesil AC; consult for heavy-traffic joint design.
Timing: Light foot traffic ~24 h; ready for use ~14 days.Pro Tip: Lift a tile periodically to verify coverage and collapse of ribs, especially over membranes.
Limitations & Safety
Product Limitations
Not for wood/wood-based boards, metals, rubber, PVC or linoleum. Use a system adhesive designed for those substrates.
Avoid moisture-sensitive or stain-prone stones. Confirm stability/compatibility, or select an alternative system adhesive.
Do not expose fresh installations to rain/running water for ~24 h; protect from frost/strong sun for 5–7 days.
Not suitable where immediate trafficking is required. Allow proper curing windows.
Safety & Handling Requirements
Personal Protective Equipment
Cement-containing powder is alkaline when wet. Wear chemical-resistant gloves, eye protection, long sleeves and appropriate footwear. Wash skin after use.
Ventilation Requirements
Provide adequate ventilation in enclosed spaces during mixing and application. Avoid dust generation; use extraction where practical.
Fire & Handling Precautions
Store dry in unopened bags; shelf life ~12 months in cool conditions. Keep away from moisture and incompatible materials.
Emergency First Aid
Eyes:
Rinse cautiously with water for several minutes; remove contact lenses if present and easy; continue rinsing and seek medical attention.
Skin:
Wash with water; remove contaminated clothing and launder before reuse.
Inhaled:
Move to fresh air and rest. Seek medical advice if symptoms persist.
Swallowed:
Rinse mouth; do not induce vomiting; seek medical attention immediately.
Seek medical attention immediately in all cases of serious exposure.
Keraflex Maxi S1 Application Guide
Cementitious Screeds & Renders (incl. heated)
Surface Preparation
Cured, sound, clean, and dry; remove laitance and contaminants. Typical cure: screeds ~28 days; renders ~1 week/cm (unless using special fast-track binders). Honor movement joints.
Primer Requirements
No primer typically required
Prime only if dusty/porous as part of site control.
—Gypsum Board & Anhydrite Screeds
Surface Preparation
Substrate must be perfectly dry (≤0.5% moisture), hard, dust-free. Sand anhydrite skin and vacuum thoroughly.
Primer Requirements
Primer required
Apply a uniform primer coat and allow to dry before trowelling the adhesive.
Primer G or Mapeprim SPExisting Tiles / Marble (Sound)
Surface Preparation
Ensure existing finish is firmly bonded, degreased and abraded if glossy; rinse and dry. Check for hollows and rectify.
Primer Requirements
Primer recommended for optimal adhesion
Use a suitable adhesion promoter where contamination risk is high.
Consult Adheseal for primer optionsWaterproofed Substrates
Surface Preparation
Membrane fully cured and compatible; clean and dry; no ponding. Verify film integrity.
Primer Requirements
No primer typically required
Ensure complete adhesive coverage; back-butter profiled tile backs.
Mapelastic AquaDefense / Smart; Mapegum WPS (substrate systems)Insulation & Acoustic Panels (Spot-Bonding)
Surface Preparation
Flat, clean substrates. Plan spot pattern to suit panel stiffness and weight.
Primer Requirements
Primer optional
Use primer only if substrate is dusty/porous.
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