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XMC750 is a one-component, moisture-curing elastic joint sealant based on alkoxy-terminated polymers. It features a low modulus, high elasticity, high elongation, and excellent water resistance. Simply put: it functions like a "soft and flexible rubber" specially designed for filling construction joints, accommodating thermal expansion and contraction without cracking easily, making it suitable for both interior and exterior applications.
| Item | XMC750 Data | Explanation |
| Appearance | White, Gray, Black | Three standard colors available upon request |
| Tack-free time (15°C) | approx. 15 min | Surface loses tack in ~15 mins, minimizing post-application damage |
| Solid content | ≥96% | High active content, low volatility, minimal shrinkage after curing |
| Curing rate | ≥3.0 mm / 24 h | Cures ~3 mm per day; deeper joints require longer curing time |
| Density | 1.25–1.39 g/cm³ | Denser than water, within standard sealant density range |
| Shore A hardness | 28–30 | Relatively soft, flexible like soft rubber, not rigid |
| 100% Secant modulus (23°C) | approx. 0.48 N/mm² | Low force required to double length (low modulus); moves with joints |
| Elongation at break | ≥750% | Extremely flexible; stretches to over 7.5 times its original length without breaking |
| Movement capacity | ±25% | Maintains seal even when joint width expands or contracts by 25% |
| Tear strength | ≥6 N/mm | Good tear resistance, preventing accidental damage |
| Sagging / Slump | 0 mm | Non-sagging on vertical surfaces; ideal for wall and overhead joints |
| Low-temperature performance | No cracking at -40°C | Resists cracking in cold climates and cold storage facilities |
| Service temperature | -45°C to 70°C | Temperature range the sealant can withstand after full cure |
| Recommended application temperature | 10–30°C | Extreme hot or cold conditions may affect application performance |
| Packaging | 310 ml cartridges; 400 ml, 600 ml sausages; 55-gallon (280 kg) drums | Options available for small repairs, regular work, and bulk requirements |
1. Tack-free time: approx. 15 minutes
This refers to the time it takes for the surface to skin over and become non-tacky. A 15-minute skin-over time is fast for sealants, making it ideal for tight schedules. Note: surface drying does not mean fully cured.
2. Solid content: ≥96%
Indicates the proportion of active components in the sealant. A value ≥96% means minimal volatile evaporation and minimal shrinkage after curing.
3. Curing rate: ≥3.0 mm / 24 h
The sealant relies on ambient moisture to cure from the surface inward. Since it cures ~3 mm per day, deep joints require patient curing before being subjected to water immersion or load stress.
4. Shore A hardness: 28–30
Lower numbers indicate a softer material. A rating of 28–30 means it remains flexible, absorbing joint movement without damaging the substrate.
5. 100% Secant modulus: approx. 0.48 N/mm²
This measures the stress needed to stretch the sealant to double its length. A low value means high flexibility, allowing it to deform with joint movement without cracking.
6. Elongation at break: ≥750%
Measures maximum stretch before breaking. Reaching ≥750% provides substantial safety margin and elasticity reserve.
7. Movement capacity: ±25%
Joints expand and contract with temperature fluctuations. A ±25% capacity means that for a 100 mm joint, it maintains a proper seal even if the width alters between 75 mm and 125 mm.
8. Sagging: 0 mm
Indicates whether the sealant slumps on vertical joints. A 0 mm rating ensures it stays in place on walls and overhead applications.
9. Low temperature: No cracking at -40°C
Does not become brittle in freezing temperatures, making it reliable for cold climate installations.
The following data is based on public technical data sheets (TDS). Please refer to manufacturers' latest documentation for official values.
| Item | XMC750 | Sika Sikaflex®-219LM | Henkel Terostat-MS 930 | Antai 332 | Baiyun SMP651 |
| Base polymer | Alkoxy polymer | 1-component Polyurethane | MS Polymer | Modified Silicone | Silane Modified Polyether |
| Tack-free time | approx. 15 min | approx. 4 h | approx. 20 min | — | — |
| Shore A hardness | 28–30 | approx. 20 | approx. 27 | — | — |
| 100% Modulus | approx. 0.48 N/mm² | — | approx. 0.5 MPa | ≤0.4 MPa | — |
| Elongation at break | ≥750% | approx. 700% | approx. 300% | — | — |
| Movement capacity | ±25% | Ref: +100/-50% | 25% | ±25% | Class 25 |
| Low-temp performance | No cracking at -40°C | -40–88°C | -40–90°C | -40–90°C | — |
| Key features | Fast skinning, high elongation, low modulus | Low modulus, high movement capacity | Similar system, comparable modulus | Commonly used in prefabricated buildings | Low modulus, flexible |
Selection Guide:
Precaution: Use Caution with Natural Stone!
Product guidelines note: "Do not use JB238 on natural stone, as plasticizer migration may cause staining." If applying to natural stone, perform a staining compatibility test first and consult technical support.
1. Application Conditions
Recommended application temperature: 10–30°C.
Optimal conditions: 15–35°C, 55%–75% RH.
Standard test condition reference: 23°C±2°C, 55%±5% RH, 168 h.
2. After Opening
Once opened, use the package on the same day or reseal strictly.
3. Low-Temperature Application
If the ambient temperature is below 10°C or extrusion rate is low, warm the package in an oven at 50°C for at least 30 minutes before use.
4. Painting
Can be painted over with most conventional exterior wall coatings, but compatibility testing must be conducted first. Paint application yields optimal results after full cure. Non-flexible coatings may impair sealant elasticity and cause paint film cracking.
5. Color Changes
Exposure to chemicals, high temperatures, or UV radiation (especially for white sealant) may cause slight discoloration. This is primarily an aesthetic factor and does not impact mechanical performance or durability.
6. Substrates to Avoid
Do not use on bituminous substrates, natural rubber, EPDM, or materials that may bleed oil, plasticizers, or solvents, as these may erode the sealant.
7. Storage
Store in a dry environment below 25°C away from high temperatures and moisture. Shelf life is typically 12 months.
8. Special Disclaimer
All handling and storage recommendations are based on current technical experience. Since jobsite conditions vary, complete compatibility testing prior to full application or consult technical services.
Q1: Is XMC750 a regular silicone sealant?
No. It is an alkoxy-terminated polymer system featuring low modulus, high elasticity, and paintability, making it better suited for structural joint movement.
Q2: Can it be painted over?
Yes, but compatibility tests should be performed first. Painting after complete curing is recommended; non-flexible paints may crack.
Q3: Can it be used on natural stone?
Use with caution. Technical notes indicate potential plasticizer staining. Perform a staining test and consult technical support prior to application.
Q4: Can it be applied in winter?
The recommended range is 10–30°C. If below 10°C, preheat the sealant at 50°C for 30 minutes, though cold substrate temperatures can still affect adhesion.
Q5: How long does it take to fully cure?
Skin-over takes ~15 minutes, but full cure depends on joint depth, curing at a rate of approx. 3 mm / 24 h.
Q6: Can it be used under water?
Technical notes indicate suitability for underwater application while maintaining low modulus adhesion. A jobsite trial is recommended.
Recommended for:
Not recommended / Proceed with caution:
