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SILISIL RTV MF-Flex 25

SILISIL RTV MF-Flex 25

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SILISIL RTV MF-Flex 25 — Transparent 2K flexible silicone Shore A 24 with high elongation at break 530%, available from Swiss stock.

2K Additive Silicone Shore A 24 (Transparent, Mixing Ratio 1:1) — Transparent 2K flexible silicone Shore A 24 with high elongation at break 530%.

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  • brand
  • Mixing ratio
  • Networking type
  • Paint has hardened
  • Self-leveling
  • Density (g/cm³)
  • Viscosity uncrosslinked (mPa·s)
  • Electrical insulation
  • Potting time (min)
  • Demolding time (min)
  • Full networking (h)
  • Food contact
  • Suitable for medical use
  • Certificates
  • Shore hardness A (cured)
  • Elongation at break (%)
  • Container

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Mold making SILISIL silicone RTV-2 Swiss bearing addition platinum prototyping Shore A 25 Swiss brand 2K mold making

 
General Terms and Conditions.

Shipping usually within 1 to 3 business days
(availability will be confirmed after ordering)

. Express logistics. Fast and reliable within Switzerland & Europe.

Shipping from Swiss warehouse within 24 hours. Batch certificate. Invoice within 30 days (B2B). Technical support.
Shipping & Delivery

Usually 1 to 3 working days

Availability will be confirmed after order receipt.

Express logistics within Switzerland & Europe.

General Terms and Conditions →

Product data

HS code: 3910.0000

HS code: 3910.0000

SILISIL RTV MF-Flex 25
SILISIL RTV MF-Flex 25
SILISIL ·

SILISIL RTV MF-Flex 25 is a room temperature vulcanizing 2-component addition silicone (platinum crosslinking, RTV-2) of the MF-Mold & Form series — Transparent 2K flexible silicone Shore A 24 with high elongation at break 530 %.

The mixture is prepared in a 1:1 ratio by weight (tolerance ±5%). Pot life at 23°C is approximately 20 minutes, demolding is possible after approximately 3 hours, and complete curing takes 24 hours. Temperature resistant from -40°C to +200°C.

Key feature

Transparent molding material with high elasticity — complete visual inspection of mold filling, air inclusions and the embedded original during demolding.

SILISIL RTV MF-Flex 25 in figures
A 24
Shore hardness
4'500
mPa·s viscosity
20 min
Pot life @23 °C
530 %
Elongation at break

What distinguishes SILISIL RTV MF-Flex 25

Transparent for visual inspection
Full visual inspection of the mold interior — air inclusions and the position of the original are always recognizable.
Low viscosity 4,500 mPa·s
Low mixing viscosity — flows into the finest structures without air inclusions, vacuum venting optional.
High elongation at break 530%
High elasticity — safe demolding of complex geometries without damage to the mold or the original.
High tensile strength >5.5 N/mm²
High tensile strength >5.5 N/mm² — above-average robustness during demolding.
Mixing ratio 1:1 by weight
Simple 1:1 ratio — mixable by hand without precision scales, ideal for workshops and hobbyists.
High-resolution reproduction
High level of detail reproduction — fonts, structures and sharp edges are reproduced true to life.

What is SILISIL RTV MF-Flex 25 used for?

Jewelry lost-wax molds
Transparent form for goldsmiths and jewelry manufacturers — embedded originals remain visible, air inclusions are detected.
Resin and epoxy art
Visually inspected casting of jewelry pendants, resin sculptures and clear resin replicas in artist studios.
Multi-part shapes with complex undercuts
Elongation at break 530% and tensile strength >5.5 N/mm² — Molded parts with aggressive undercuts can be safely demolded.
Designer prototypes with visual inspection
Industrial design and product studios check during demolding whether undercuts are correctly molded.
Collector and model-making replicas
High-resolution reproduction of small series — action figures, model railway parts, collector's editions.
Educational and museum replicas
Transparent teaching materials, anatomical models and didactic replicas show the structure even after hardening.

processing

1
Prepare the original
The surface to be reproduced must be clean, dry, and dust-free. The ideal processing temperature is 23°C — cooler environments significantly extend the pot life and curing time.
2
homogenize and mix components
Stir the base and catalyst thoroughly before use. Weigh out 1:1 by weight (tolerance ±5%). When mixing, thoroughly incorporate the mixture into the container walls and bottom.
3
Vacuum venting
For non-porous molds, briefly de-aerate the mixture under vacuum — trapped air bubbles are removed and a smooth mold surface is guaranteed.
4
Pour slowly into the mold
Pour in a thin stream from a height of approximately 30 cm into the lowest point — the silicone displaces air on its own and reaches all undercuts.
5
Vulcanizing and demolding
At 23 °C, demolding is possible after approximately 3 hours, with complete curing after 24 hours. A 24-hour "maturation phase" is required before the first casting to ensure maximum strength.
Data sheets & safety data sheet
Full TDS and SDS in DE, EN, FR — view or download directly.
To the documents →

Important instructions

Avoid crosslinking inhibitors
Additive systems like MF-Flex 25 are sensitive to sulfur, amine, tin, and phosphorus compounds—especially latex gloves, modeling clay, adhesive tapes, and some paints. If in doubt, make a small test cast before use.
Storage and shelf life
In its unopened original container, the product has a shelf life of at least 12 months when stored in a dry, cool place (10–25 °C). Consult the Safety Data Sheet (SDS) before opening.
Available packaging
1 kg + 1 kg, 5 kg + 5 kg, 25 kg + 25 kg. Other package sizes available on request.
compatibility
Compatible with polyurethane, epoxy, and polyester casting resins. Apply a release agent to protect the mold when using aggressive resins.

Recommended accessories

SILISIL Vaseline release paste white
Universal release agent for polyester, epoxy and polyurethane casts — protects the silicone mold from aggressive resins and extends the mold's lifespan.
View product →
SILISIL Delayer PA
Retarder for addition silicones — extends pot life and setting time for more complex multi-part structures and relaxed processing.
View product →
SILISIL Silicone Remover
Cleaning agent for silicone residues on tools, models and work surfaces — gentle and effective.
View product →

Which MF silicone for which application?

SILISIL RTV MF-Flex 25 in direct comparison with related MF products in our range (MF = Mold & Form).

MF-Flex 25
Current product 		MF-Flex 20 →MF-Soft 12 →MF-Soft 13 TP →
Shore hardness A24221213
Mixed viscosity4'5004'5003'5004'500
ColorTransparentBlueBlueTranslucent
Pot life @23 °C20152045
Topics & Application Areas
Key terms related to this product. Also useful for our search and filters.
Mold making SILISIL silicone RTV-2 Swiss bearing addition platinum prototyping Shore A 25 Swiss brand 2K mold making

Technical data for SILISIL RTV MF-Flex 25

All 17 product information 4 Physical properties 4 Electrical properties 1 Curing values ​​3 Product approvals 3 Mechanical properties 2
Product information
brand SILISIL
Mixing ratio 1:1
Networking type Addition (Platinum)
Container 500g+500g, 1kg+1kg, 5kg+5kg, 10kg+10kg, 25kg+25kg
Physical properties
Paint has hardened Transparent
Self-leveling Yes
Density (g/cm³) 1.1
Viscosity uncrosslinked (mPa·s) 4500
Electrical properties
Electrical insulation Yes
Curing values
Potting time (min) 20
Demolding time (min) 3
Full networking (h) 24
Product approvals
Food contact No
Suitable for medical use No
Certificates RoHS, REACH
Mechanical properties
Shore hardness A (cured) A 25
Elongation at break (%) 530

For binding values, please refer to the technical data sheet (TDS) in the "Documents" tab.

Documents and datasheets

Click on a document for a preview or the download icon for a direct download.

Technical Data Sheets (TDS) 3
SILISIL RTV MF-Flex 25 - Technical Data Sheet DE.pdf
124 KB
SILISIL RTV MF-Flex 25 - Technical Data Sheet EN.pdf
123 KB
SILISIL RTV MF-Flex 25 - Fiche Technique FR.pdf
123 KB

Frequently asked questions about SILISIL RTV MF-Flex 25

Practical application and design questions — answered by SILITECH.

SILISIL RTV MF-Flex 25 is a two-component (Shore A 24, transparent) addition silicone for jewelry lost-wax casting and related applications. Transparent two-component flexible silicone, Shore A 24, with high elongation at break (530%)

At 23 °C, the pot life is approximately 20 minutes and the demolding time approximately 3 hours. Complete curing is achieved after 24 hours. Lower temperatures extend, higher temperatures shorten these times.

As an addition system, SILISIL RTV MF-Flex 25 is sensitive to crosslinking inhibitors: sulfur, amine, tin, and phosphorus compounds can locally halt vulcanization. Avoid latex gloves, sulfur-containing modeling clays, some adhesive tapes, and PVC plasticizers in the immediate vicinity of the mold. If in doubt, make a small test cast.

SILISIL RTV MF-Flex 25 is mixed in a 1:1 ratio by weight (base to catalyst), with a maximum tolerance of ±5%. Homogenize both components separately before mixing, then thoroughly incorporate them – including the container walls and bottom. Brief vacuum degassing of the mixture is recommended for non-porous molds.

SILISIL RTV MF-Flex 25 achieves a Shore A hardness of 24 (ASTM D 2240), a tensile strength of >5.5 N/mm² (ASTM D 412), an elongation at break of approximately 530 % and a tensile strength of 15 N/mm (ASTM D 624).

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Product specifications

Product information
Container 500g + 500g or 1kg + 1kg or 5kg + 5kg or 10kg + 10kg or 25kg + 25kg
brand SILISIL
Mixing ratio 1:1
Networking type Addition (Platinum)
Physical properties
Paint has hardened Transparent
Self-leveling Yes
Density (g/cm³) 1.1
Viscosity uncrosslinked (mPa·s) 4500
Electrical properties
Electrical insulation Yes
Curing values
Potting time (min) 20
Demolding time (min) 3
Full networking (h) 24
Product approvals
Certificates RoHS or REACH
Food contact No
Suitable for medical use No
Mechanical properties
Shore hardness A (cured) A 25
Elongation at break (%) 530
Keywords
Keywords
Mold making SILISIL silicone RTV-2 Swiss bearing addition platinum prototyping Shore A 25 Swiss brand 2K mold making

Documents and datasheets

Safety Data Sheets (SDS) and Technical Data Sheets (TDS) are available for download: