SILISIL RTV MF-PuttyFast 38

SILISIL ·

SILISIL RTV MF-PuttyFast 38 is a room temperature vulcanizing 2-component addition silicone (platinum crosslinking, RTV-2) of the MF-Mold & Form series — 2K putty Shore A 38 — fast reproduction without mold tooling.

The mixture is prepared in a 1:1 ratio by weight (tolerance ±5%). Pot life at 23°C is approximately 3 minutes, demolding after approximately 12 minutes, and complete curing after 24 hours. Temperature resistant from -40°C to +200°C.

Key property

2-component modeling clay for the fastest mold production: Knead base and catalyst (1:1) between your hands and press directly onto the model — mold ready in 12 minutes.

SILISIL RTV MF-PuttyFast 38 in figures

A 38

Shore Hardness

modeling clay

Consistency

3 min

Pot life @23 °C

200 %

Elongation at break

What distinguishes SILISIL RTV MF-PuttyFast 38

Modeling clay — no container needed

Direct hand processing without container, mixer or vacuum chamber — the fastest way to the shape.

Pot life 3 minutes

Very short processing time — suitable for high-throughput production with short mold cycles.

Setting time 12 minutes

Controlled setting time — reliable planning of the mold cycle.

Heat resistant for low-temperature metals

Suitable for direct casting of low-melting alloys — Wood's Metal, Sn-Bi solders, <200 °C.

Mixing ratio 1:1

Simple 1:1 ratio — hand-mixable without a precision scale, ideal for workshops and hobbyists.

Simple processing by hand

Direct hand processing — no mixing machine, no vacuum, no special tools required.

What is SILISIL RTV MF-PuttyFast 38 used for?

Instant molds without tools

Mix the modeling clay between your hands and press it directly onto the model — creating shapes where no container is possible or desired.

Repair and model correction

Putty fills cracks, damage and missing areas — vulcanizes to Shore A 38 in 12 minutes.

Low-melt alloy castings

Temperature resistant up to +200 °C — suitable for Sn-Bi solders, Wood's Metal and model maker alloys with a melting point well below 200 °C, without preform.

Fast, detailed molding in jewelry

A pot life of 3 minutes is sufficient to create a putty mold directly on a piece of jewelry — ready for wax casting in 15 minutes.

Mobile on-site impressions

Perfect for everyday restoration and museum use — putty ready to use without mixer, vacuum or container.

Maker and hobby prototyping

Easiest 1:1 processing by hand — perfect for training, maker spaces and DIY projects.

Processing

Prepare the original

The surface to be reproduced must be clean, dry, and free of dust. The ideal processing temperature is 23 °C — cooler environments significantly extend pot life and curing time.

Homogenize and mix components

Stir base and catalyst thoroughly before use. Weigh out 1:1 by weight (tolerance ±5%). When mixing, thoroughly incorporate the walls and bottom of the container.

Vacuum degassing

For pore-free molds, briefly degas the mixture under vacuum — entrapped air bubbles are removed, ensuring a smooth mold surface.

Pour slowly into the mold

Pour from a height of approx. 30 cm in a thin stream into the deepest point — the silicone displaces air independently and reaches all undercuts.

Vulcanize and demold

At 23 °C, demolding is possible after approximately 12 minutes; complete curing takes 24 hours. A 24-hour "maturation phase" is required before the first casting to ensure maximum strength.

Data Sheets & Safety Data Sheet

Complete TDS and SDS in DE, EN, FR — view or download directly.

To the documents →

Important Notes

Avoid crosslinking inhibitors

Additive systems like MF-PuttyFast 38 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 casting before use.

Storage and Shelf Life

Shelf life of at least 12 months in unopened original container when stored in a dry, cool place (10–25 °C). Consult the Safety Data Sheet (SDS) before opening.

Available containers

1 kg + 1 kg, 5 kg + 5 kg. Other container sizes available on request.

Compatibility

Compatible with polyurethane, epoxy, and polyester casting resins. For aggressive resins, apply a release agent to protect the mold.

Recommended accessories

SILISIL white petroleum jelly release paste

Universal release agent for polyester, epoxy, and polyurethane casts — protects the silicone mold from aggressive resins and extends mold service life.

To the product →

SILISIL Delayer PA

Retarder for addition-curing silicones — extends pot life and setting time for more complex multi-part builds and relaxed processing.

To the product →

SILISIL Silicone Remover

Cleaning agent for silicone residues on tools, models, and work surfaces — gentle and effective.

To the product →

Which MF silicone for which application?

SILISIL RTV MF-PuttyFast 38 in direct comparison with related MF products in our range (MF = Mold & Form).

	MF-PuttyFast 38 Current Product	MF-Spray 25-6 →	MF-Dura 35 Fast →	MF-Dura 30 →
Shore hardness A	38	25	35	?
Mixed viscosity	(Play-Doh)	8'000	7'500	?
Color	Light Violet	Light blue	Green	?
Pot life @23 °C	3	6	1	?

Topics & Application Fields

Key terms related to this product. Also useful for our search and filters.

Mold making SILISIL Silicone RTV-2 Swiss Bearing Addition Platinum Prototyping Swiss Brand 2K Moulding / Mold making Fast Putty / Kneadable Shore A 38 Price list missing

Technical data for SILISIL RTV MF-PuttyFast 38

All 15 product information 2 Physical properties 3 Electrical properties 1 Curing values 2 Product approvals 3 Mechanical properties 4

Product Information
Curing type	Addition (Platinum)
Container	500g+500g, 1kg+1kg, 25kg+25kg

Physical Properties
Cured Color	Light Violet
Self-leveling	Thixotropic
Density (g/cm³)	1.42

Electrical Properties
Electrical Insulation	Yes

Curing values
Demolding time (min)	12
Full cure (h)	24

Product Approvals
Food contact	No
Medical grade	No
Certificates	RoHS, REACH

Mechanical properties
Shore hardness A (cured)	A 38
Tensile strength (MPa)	1.3
Elongation at break (%)	200
Tear strength (N/mm)	4

Please refer to the technical data sheet (TDS) in the "Documents" tab for binding values.

Documents and data sheets

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

Technical Data Sheets (TDS) 3

SILISIL RTV MF-PuttyFast 38 - Technical Data Sheet DE.pdf

149 KB

SILISIL RTV MF-PuttyFast 38 - Technical Data Sheet EN.pdf

152 KB

SILISIL RTV MF-PuttyFast 38 - Technical Data Sheet FR.pdf

155 KB

Safety Data Sheets (SDS) 3

SILISIL RTV MF-PuttyFast 38 - Safety Data Sheet DE.pdf

334 KB

SILISIL RTV MF-PuttyFast 38 - Safety Data Sheet EN.pdf

358 KB

SILISIL RTV MF-PuttyFast 38 - Fiche de Sécurité FR.pdf

363 KB

Frequently asked questions about SILISIL RTV MF-PuttyFast 38

Practical application and design questions — answered by SILITECH.

What is SILISIL RTV MF-PuttyFast 38 suitable for?

SILISIL RTV MF-PuttyFast 38 is a two-component (Shore A 38, light purple) additive silicone for instant molding without tooling and related applications. Two-component putty Shore A 38 — fast reproduction without molding tools

What is the pot life and demolding time of MF-PuttyFast 38?

At 23 °C, the pot life is approximately 3 minutes and the demolding time approximately 12 minutes. Complete curing is achieved after 24 hours. Lower temperatures extend, higher temperatures shorten these times.

Which materials should be avoided when using MF-PuttyFast 38?

As an addition system, SILISIL RTV MF-PuttyFast 38 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 casting.

What mixing ratio is used for MF-PuttyFast 38?

SILISIL RTV MF-PuttyFast 38 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.

What is the Shore hardness and mechanical properties of MF-PuttyFast 38?

SILISIL RTV MF-PuttyFast 38 achieves a Shore A hardness of 38 (ASTM D 2240), a tensile strength of 1.3 N/mm² (ASTM D 412), an elongation at break of approximately 200% and a tear resistance of 4 N/mm (ASTM D 624).

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Product Specifications

Product Information
Container	500g + 500g or 1kg + 1kg or 25kg + 25kg
Curing type	Addition (Platinum)

Physical Properties
Cured Color	Light Violet
Self-leveling	Thixotropic
Density (g/cm³)	1.42

Electrical Properties
Electrical Insulation	Yes

Curing values
Demolding time (min)	12
Full cure (h)	24

Product Approvals
Certificates	RoHS or REACH
Food contact	No
Medical grade	No

Mechanical properties
Shore hardness A (cured)	A 38
Tensile strength (MPa)	1.3
Elongation at break (%)	200
Tear strength (N/mm)	4

Keywords
Keywords	Mold making SILISIL silicone RTV-2 Swiss bearing additive Platinum prototyping Swiss brand 2K Moulding / Mold making Fast Putty / Kneadable Shore A 38

Documents and data sheets

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

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SILISIL RTV MF-PuttyFast 38

Price on request

Documents

Shipping & Delivery

Product data

What distinguishes SILISIL RTV MF-PuttyFast 38

What is SILISIL RTV MF-PuttyFast 38 used for?

Processing

Important Notes

Recommended accessories

Which MF silicone for which application?

Technical data for SILISIL RTV MF-PuttyFast 38

Documents and data sheets

Technical Data Sheets (TDS) 3

Safety Data Sheets (SDS) 3

Frequently asked questions about SILISIL RTV MF-PuttyFast 38

Your question not covered?

Product Specifications

Documents and data sheets