ELASTOSIL® M 4642 A/B and MinghuiLink RTV-4135 are both medium-hard addition-cure mold silicones, with M 4642 at approximately 37 Shore A and RTV-4135 at 35±1 Shore A. M 4642 offers higher published tensile, tear and elongation values, a 90-minute working window and positioning for demanding reproduction and undercut molds. RTV-4135 offers simpler 1:1 mixing, lower published component viscosity and a shorter published cure time.
Addition-Cure Silicone
Platinum-Cure Silicone
ELASTOSIL® M 4642 A/B is better suited to demanding reproduction molds where higher mechanical performance, a longer working window and undercut capability are important. RTV-4135 is better aligned with users who prioritize simple 1:1 mixing, lower published component viscosity and shorter published cure time.
ELASTOSIL® M 4642 A/B and RTV-4135 are close in hardness, with M 4642 at 37 Shore A and RTV-4135 at 35±1 Shore A. M 4642 is slightly firmer, while both remain suitable for medium-hard reusable molds.
The biggest processing difference is the mixing system and working window. M 4642 uses a 10:1 ratio with approximately 90 minutes of pot life, while RTV-4135 uses a simpler 1:1 ratio and approximately 35 minutes of working time. M 4642 therefore provides substantially more time for large or complex mold preparation, while RTV-4135 is easier to proportion for small manual batches.
Viscosity also favors RTV-4135 for routine handling. M 4642 publishes approximately 20,000 mPa·s for Part A and 700 mPa·s for Part B, with approximately 15,000 mPa·s mixed viscosity. RTV-4135 publishes approximately 4,500 mPa·s for Part A and 4,000 mPa·s for Part B. The component values should be considered together with the different mix ratios, but RTV-4135 has the lower published component viscosities.
M 4642 has the stronger published mechanical profile. It reports 7.0 MPa tensile strength, >30 N/mm tear strength and 480% elongation, compared with 4.8±0.5 MPa, 28 N/mm and 300±50% for RTV-4135. The higher tensile and tear values provide greater published mechanical margin, while the higher elongation supports more demanding flexible demolding.
WACKER specifically positions M 4642 for reproduction molds with undercuts and resistance to common casting resins. This makes it particularly relevant to demanding reusable molds where both dimensional reproduction and mechanical durability matter. RTV-4135 is better characterized as a general-purpose A35-class platinum-cure silicone for routine mold making and casting.
Published turnaround favors RTV-4135, although the reported endpoints differ. WACKER lists approximately 12 hours to a tack-free state for M 4642, while MinghuiLink lists approximately 5 hours cure time for RTV-4135. These values are not directly equivalent test endpoints, but RTV-4135 is better aligned with shorter published routine production cycles.
Both materials are low-shrinkage addition-cure silicones. M 4642 publishes less than 0.1% linear shrinkage, while RTV-4135 publishes no more than 0.1%. For large molds, mold-wall thickness, support structure and casting weight still need to be considered regardless of the selected silicone.
Overall, M 4642 is differentiated by higher published mechanical performance, a much longer working window and explicit positioning for demanding reproduction and undercut molds. RTV-4135 is differentiated by 1:1 processing, lower published component viscosity and shorter published cure time.
| Technical Parameter | WACKER ELASTOSIL® M 4642 A/B | MinghuiLink RTV-4135 |
|---|---|---|
| Silicone Type | Addition-cure RTV-2 | Platinum-cure silicone |
| Color | White | Translucent |
| Mix Ratio | 10:1 by weight | 1:1 by weight or volume |
| Shore Hardness | 37 Shore A | 35±1 Shore A |
| Viscosity | 20,000 mPa·s (Part A) | 4,500 mPa·s (Part A) |
| Working / Pot Life | 90 min | 35 min |
| Demold / Cure Time | 12 h tack-free | 5 h cure |
| Tensile Strength | 7.0 MPa | 4.8±0.5 MPa |
| Tear Strength | >30 N/mm | 28 N/mm |
| Elongation | 480% | 300±50% |
| Shrinkage | <0.1% | ≤0.1% |
| Temperature Resistance | Not publicly listed as an equivalent numerical service rating | Up to 250°C / 482°F |
| Typical Applications | Reproduction molds, casting-resin molds and undercut models requiring mold rigidity | Reusable molds, resin casting and general A35-class mold making |
| Technical Data Sources | ELASTOSIL® M 4642 A/B | RTV-4135 |
| Key Factor | WACKER ELASTOSIL® M 4642 A/B | MinghuiLink RTV-4135 |
|---|---|---|
| Hardness | 37 Shore A | 35±1 Shore A |
| Mixing System | 10:1 | 1:1 |
| Working Window | 90 min | 35 min |
| Component Viscosity | 20,000 / 700 mPa·s | 4,500 / 4,000 mPa·s |
| Tensile Strength | 7.0 MPa | 4.8±0.5 MPa |
| Tear Strength | >30 N/mm | 28 N/mm |
| Elongation | 480% | 300±50% |
| Mold Turnaround | 12 h tack-free | 5 h cure |
| Application Focus | Reproduction, casting-resin and undercut molds | General-purpose A35-class mold making |
| Application | ELASTOSIL® M 4642 A/B | RTV-4135 |
|---|---|---|
| Complex Reproduction | Strong candidate | Strong candidate |
| Undercut Molds | Strong candidate | Suitable |
| Large / Complex Molds | Strong candidate | Suitable |
| Thin Mold Edges | Strong candidate | Strong candidate |
| Repeated Casting | Strong candidate | Strong candidate |
| Rapid Routine Production | Suitable | Strong candidate |
Tell us your application. We’ll recommend the right RTV-2 silicone and provide a sample for testing.
Competitor specifications are based on publicly available manufacturer documentation, with links to the original sources where available. Missing values are shown as “Not publicly listed” and are not estimated or inferred. Specifications may change, so always check the latest manufacturer documentation and conduct application-specific testing before production use. Product names and trademarks belong to their respective owners. This comparison is provided for technical and informational purposes only and is not endorsed by the brands mentioned.