Shin-Etsu SES22256/CAT22256-40 and MinghuiLink RTV-4140 are both firm silicone systems for reusable molds, with published cured hardness values of 38 Shore A and 40±1 Shore A respectively. The more meaningful difference is mechanical performance: SES22256 publishes substantially higher tear strength and elongation, while RTV-4140 offers simpler 1:1 mixing, lower published component viscosity and a much shorter cure cycle.
Addition-Cure Silicone
Platinum-Cure Silicone
SES22256/CAT22256-40 and RTV-4140 are aimed at similar firm mold applications, but their strengths are different. SES22256 is the more performance-oriented option when tear resistance, elongation and high-modulus mold behavior are important, while RTV-4140 is the more processing-oriented option for users who prioritize simple batching, lower component viscosity and faster curing.
SES22256/CAT22256-40 and RTV-4140 are both firm silicone systems for reusable mold making, with published cured hardness values of 38 Shore A and 40±1 Shore A respectively. Their hardness is therefore broadly comparable. The more meaningful differences are SES22256's exceptionally high published tear strength and high-modulus positioning versus RTV-4140's simpler processing and faster cure.
Shin-Etsu positions SES22256/CAT22256-40 as a high-strength, high-modulus addition-cure mold-making silicone with low shrinkage and easy release. Its most distinctive published mechanical property is 43.037 N/mm tear strength, compared with 32±0.5 N/mm for RTV-4140. SES22256 also reports 315% elongation, versus 220±50% for RTV-4140. This combination can be relevant when a reusable mold is exposed to repeated opening, local tearing or mechanical stress around cuts and parting lines.
The tensile-strength values are much closer. SES22256 reports 5.01 MPa, while RTV-4140 reports 5.3±0.5 MPa. The published data therefore do not show a meaningful tensile-strength advantage for either product. SES22256's more notable mechanical distinction is the combination of higher tear strength, higher elongation and a published modulus of 1.196 MPa at 100% strain.
Tear strength, elongation and modulus address different aspects of mold behavior. Higher tear strength can help resist crack or cut propagation, elongation indicates the ability to stretch during handling and demolding, while modulus relates more closely to resistance to deformation under strain. For molds where both structural support and resistance to mechanical damage matter, the complete property profile is more informative than any single number.
Processing is where RTV-4140 has the clearer practical advantage. It uses a 1:1 mixing ratio by weight, compared with 100:10 for SES22256/CAT22256-40. MinghuiLink also publishes approximately 4,800 mPa·s for Part A and 4,300 mPa·s for Part B, while Shin-Etsu reports approximately 65 Pa·s base viscosity and 39,000 cP mixed for SES22256. Because the manufacturers use different measurement points and material states, these figures should not be treated as a strict viscosity ratio, but RTV-4140 is positioned for simpler routine mixing and handling.
Working time is not a major differentiator in this comparison. SES22256/CAT22256-40 is published with a 30-minute working time, while RTV-4140 is published with a 30–40 minute window. Both therefore require a conventional relatively short mold-preparation workflow. Users should not select SES22256 primarily for additional processing time.
Cure time creates a much clearer production difference. SES22256/CAT22256-40 is published with a 24-hour cure at 23°C, compared with approximately 5–6 hours for RTV-4140. RTV-4140 is therefore better suited to production environments where faster mold turnover or more frequent mold replacement is important.
At around A40 hardness, both materials provide more mold body and dimensional support than softer A20–A30 grades. This can be useful for larger molds and applications where deformation needs to be controlled. At the same time, A40-class silicone is less flexible than softer grades, so deep undercuts and thin sections may require more careful parting-line design and demolding procedures.
SES22256/CAT22256-40 is therefore most attractive when mechanical durability is a primary concern, particularly where high tear strength, elongation and high-modulus behavior are valuable. RTV-4140 is better aligned with users who place greater emphasis on simple batching, lower published component viscosity and faster curing. The choice should be based on the mold's failure risks and production workflow rather than hardness alone.
| Technical Parameter | Shin-Etsu SES22256/CAT22256-40 | MinghuiLink RTV-4140 |
|---|---|---|
| Silicone Type | Addition-cure silicone | Platinum-cure silicone |
| Color | Not publicly listed | Translucent |
| Specific Gravity | 1.10817 g/cm³ combined | 1.08–1.10 g/cm³ |
| Mix Ratio | 100:10 by weight | 1A:1B by weight |
| Shore Hardness | 38 Shore A | 40±1 Shore A |
| Viscosity | 39,000 cP (Mixed) | 4,800±200 mPa·s* (Part A) |
| Working / Pot Life | 30 min | 30–40 min |
| Snap Time | 55 min | Not publicly listed |
| Cure Time | 24 hours at 23°C | 5–6 hours |
| Modulus @100% | 1.196 MPa | Not publicly listed |
| Tensile Strength | 5.01 MPa | 5.3±0.5 MPa |
| Tear Strength | 43.037 N/mm | 32±0.5 N/mm |
| Elongation | 315% | 220±50% |
| Shrinkage | Low shrinkage; numerical value not publicly listed | ≤0.1% |
| Temperature Resistance | Not publicly listed | Up to 250°C / 482°F |
| Technical Data Sources | SES22256/CAT22256-40 | RTV-4140 |
| Key Factor | Shin-Etsu SES22256/CAT22256-40 | MinghuiLink RTV-4140 | What It Means |
|---|---|---|---|
| Cured Hardness | 38 Shore A | 40±1 Shore A | Both are firm mold silicones, with SES22256 slightly softer on the published cured-hardness values. |
| Tear Strength | 43.037 N/mm | 32±0.5 N/mm | SES22256 has the clear published tear-strength advantage, which can matter when molds are exposed to cuts, sharp edges and repeated opening. |
| Elongation | 315% | 220±50% | SES22256 publishes higher elongation, providing greater stretch capability during handling and demolding. |
| Modulus | 1.196 MPa @100% | Not publicly listed | SES22256 has a published modulus value consistent with its high-modulus mold-making positioning. |
| Working Window | 30 min | 30–40 min | The working windows are broadly similar, so processing time is not a major differentiator between these products. |
| Mixing System | 100:10 by weight | 1A:1B by weight | RTV-4140 is simpler to measure and batch for routine manual production. |
| Published Viscosity | 39,000 cP mixed | 4,800±200 mPa·s Part A | RTV-4140 publishes a substantially lower component viscosity, although the measurement points are not identical. |
| Cure Cycle | 24 h at 23°C | 5–6 h | RTV-4140 is better aligned with applications requiring faster mold turnover. |
| Temperature Capability | Not publicly listed | Up to 250°C | RTV-4140 has the higher publicly listed temperature specification. |
| Process Positioning | High tear strength, high modulus and mechanical durability | Simple, fast and practical firm-mold production | The main choice is between mechanical durability and processing convenience. |
| Application | SES22256/CAT22256-40 | RTV-4140 | Key Consideration |
|---|---|---|---|
| Repeated Demolding | Strong candidate | Strong candidate | SES22256 combines higher published tear strength and elongation, which can be valuable when the mold is repeatedly flexed or exposed to local tearing stress. |
| Large / Firm Molds | Strong candidate | Strong candidate | Both provide firm mold behavior; the choice depends more on mechanical requirements, handling and production cycle than hardness alone. |
| Precision / Dimensional Molds | Strong candidate | Strong candidate | Both are suitable for firm molds where dimensional support is important. SES22256 also provides a published modulus value, while RTV-4140 offers simpler processing. |
| Complex Undercut Molds | Suitable | Suitable | Both are relatively firm materials. SES22256's higher elongation may provide more stretch capability, but difficult undercuts still require suitable mold design and parting lines. |
| Routine Mold Production | Suitable | Strong candidate | RTV-4140's 1:1 mixing system and shorter cure cycle are better suited to repeatable everyday production. |
| Rapid Prototyping | Suitable | Strong candidate | RTV-4140's published 5–6 hour cure supports faster mold iteration. |
| Resin Casting | Strong candidate | Strong candidate | Both can be evaluated for reusable resin molds. Resin chemistry, mold durability and repeated demolding conditions should be considered. |
| Small-Batch Manual Mixing | Suitable with accurate weighing | Strong candidate | RTV-4140's 1:1 system is simpler to measure and reduces batching complexity for small production runs. |
| 3D-Printed Masters | Suitable with compatibility testing | Suitable with compatibility testing | UV-resin residues, coatings and other contaminants can inhibit addition-cure silicone. A small compatibility test is recommended before production. |
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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.