FDA-Approved Medium Hardness Platinum Cured Liquid Silicone Rubber

FDA odor free ​ non toxic 20-35 A platinum-catalyst addition
Lead Time
Quantity(kilograms)1-10001000-5000≥5000
Est. Time(days)2-3 4-7To Be Negotiated

1. Description

This series of addition-cure (platinum-catalyzed) silicone is a medium-hardness, flexible elastomeric material. Both Part A and Part B are translucent viscous liquids that can be colored with silicone pigments to achieve a wide range of colors. After mixing the two parts in a 1A:1B weight or volume ratio, curing can be completed at room temperature within several hours or accelerated by heating.

After curing, this series of silicone rubber materials are heat-resistant, non-toxic, and odorless. They have been tested and comply with FDA regulations for CFR 177.2600 extractable testing, making them safe for use in contact with food.

addition cure silicone

2. Feature

  1. 1A:1B ratio, easy to use.
  2. It has good flexibility and elasticity.
  3. High tear strength and excellent elongation.
  4. Very low shrinkage for extremely accurate molds.
  5. Heat resistant up to 250°C (482°F).
  6. It reproduces fine details accurately.
platinum cure silicone

3. Application

This medium-hardness platinum-cured silicone rubber is a high-performance material with excellent tear strength, tensile strength, elongation, low shrinkage rate, and accurate detail reproduction. They are very suitable for mold making in various materials and industries, ranging from epoxy resin, polyester, cement, concrete, gypsum, to low-melting point metals that require heat resistance.

resin silicone mold

Resin Silicone Mold

resin bracelet silicone mold

Resin Bracelet Mold

cultural brick silicone mold

Cultural Brick Mold

simulation corn silicone mold

Simulation Corn Mold

4. Attention

  1. Please use parts A and B of the same model and lot number. If different batches are used, suitability should be determined by testing.
  2. For optimal results, mix and cure the material at 20-30°C (68-86°F) and 50% relative humidity. Addition-cured liquid silicone should not be used in humid conditions, as this may cause defective curing.
  3. Lower temperatures and humidity will increase the working time of the material. Do not use platinum-cured silicone at temperatures below 15°C (60℉), as it may not cure properly or may be difficult to cure at all.
  4. Platinum-cured liquid silicone needs to be used with care to avoid inhibition. Inhibition occurs when the platinum cure silicone doesn't fully cure due to contamination on the surface of the object being molded. Although it may appear to be fully cured on the surface, a tacky surface will be present after separation - this is called inhibition. Amines, tin compounds, sulfur-based clay, newly cast polyester, natural rubber such as latex and rubber gloves, PVC stabilizers, epoxy resin catalysts, UV curable resin, or urethane rubber may cause inhibition. If compatibility between the addition cure silicone and the surface is a concern, it is recommended to perform a small-scale test. Do not smoke during operation.

5. Safety

  1. Under normal storage and handling conditions, these products are stable in airtight containers at room temperature and will not undergo any hazardous reactions.
  2. Please keep out of reach of children.
  3. First Aid Measures:
    • Skin Contact: Wash the affected skin thoroughly with soap and water. Seek medical attention if symptoms persist after washing.
    • Eye Contact: In the event of contact with the eyes, rinse them thoroughly with clean water for at least 15 minutes. Seek medical attention if irritation persists after rinsing.
    • Inhalation: Under normal conditions of intended use, this material is not expected to be an inhalation hazard.
    • Ingestion: Do not induce vomiting unless instructed by a physician. Rinse mouth thoroughly. Seek medical attention if symptoms occur.

Please note that these measures are general guidelines. In case of an emergency, always consult a medical professional or seek immediate medical attention.

6. Storage

When stored at room temperature (15 to 25°C / 60 to 77°F), the material has a shelf life of 24 months from the date of manufacture. Storing the material at higher temperatures may shorten the usable shelf life of unused materials. However, storing the product beyond the specified date on the certificate of analysis does not necessarily mean that the product is no longer usable.

Containers that have been opened must be carefully resealed to prevent leakage. Store in a cool, dry place with adequate ventilation and keep away from incompatible materials (such as bases and acids), open flames, and high temperatures.

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Parameter Item Test Method RTV-4120 A/B RTV-4125 A/B RTV-4130 A/B RTV-4135 A/B
Unvulcanized Physical Properties @ 24 Hrs 25°C/77°F
Physical State - Liquid Liquid Liquid Liquid
Form - Viscous Viscous Viscous Viscous
Odor - Odorless Odorless Odorless Odorless
Part A Color ASTM E 1767 Translucent Translucent Translucent Translucent
Part B Color ASTM E 1767 Translucent Translucent Translucent Translucent
Part A Viscosity, mPa.s ASTM D 4287 8,000 10,000 11,000 17,000
Part B Viscosity, mPa.s ASTM D 4287 7,000 9000 10,000 15,000
Specific Gravity, g/cm3 ASTM D 792 1.05-1.07 1.05-1.07 1.05-1.07 1.05-1.07
Part A and Part B mixed @ 25°C/77°F
Mix Ratio by Weight or Volume (A:B) - 1:1 1:1 1:1 1:1
Working Time, Minutes - 40 40 40 40
Curing Time, Hours - 5 5 6 6
Typical Properties of Cured Rubber @ 24 Hrs 25°C/77°F
Hardness, Shore A Durometer ASTM D 2240 20 25 30 35
Tear Strength, N/mm ASTM D 624 C 17.0 18.0 18.0 17.0
Tensile Strength, Mpa ASTM D 412 3.8 4.0 4.2 4.4
Elongation, % ASTM D 412 430 400 380 350
Shrinkage, % - ≤0.20 ≤0.20 ≤0.15 ≤0.10
Heat Resistance, °C (°F) - 250 (482) 250 (482) 250 (482) 250 (482)

Step 1: Model Preparation

The master pattern should be thoroughly cleaned and dried. If the master model is fragile, weak, or porous, it may be necessary to apply a consolidant or sealant, and possibly fill in deep holes or crevices.

Step 2: Applying Release Agent

This series of silicones is highly regarded for its exceptional demolding performance, making the use of a demolding agent unnecessary for most materials. However, in cases where the master pattern exhibits high porosity, a rough texture, numerous cracks and undercuts, or is difficult to demold, it is advisable to apply a thin layer of demolding agent. This not only facilitates the demolding process by reducing friction and adhesion but also helps to extend the lifespan of the mold.

Commonly used demolding agents include acrylic spray, Vaseline, silicone oil, and soapy water, among others. These agents provide effective release properties, allowing for easier removal of the molded object from the mold.

Step 3: Measuring & Mixing

Mix the desired amount of Parts A and B in a 1:1 (by volume or weight) ratio and thoroughly mix them together. Accurate measurement is essential to achieve the best physical properties of the cured rubber. If you wish to add color to the silicone material, incorporate the desired colorant into the mixture. Mix the colorant thoroughly to achieve a uniform color throughout the material.

Step 4: Vacuum Degassing

You can assess the need for vacuum degassing based on the specific requirements of each project, but it is still recommended for achieving a flawless finish. If using vacuum degassing, place the mixed silicone in a container that is 3-4 times larger than the volume of the liquid silicone and vacuum degas until the silicone rises and then collapses. Continue vacuum degassing for an additional 1 to 2 minutes.

Techniques to Reduce Air Bubbles:

  1. Hold the silicone container high above the master pattern and allow it to flow down slowly in a thin stream. This helps to break up any air bubbles as the silicone flows.
  2. Temporarily incline the master pattern at an angle and pour the liquid silicone onto the higher end, allowing it to flow down over the rest of the pattern. Once the silicone reaches the lower end, lay the pattern flat and/or tilt or rotate it as necessary to achieve even coverage.

These techniques can be used alone or in combination with each other. Additionally, reducing the temperature and decreasing the ratio of curing agent can extend the working time and help to reduce air bubbles.

Step 5: Pouring Silicone

Pour the liquid silicone as soon as possible after mixing or vacuuming to achieve the best flow and air bubble release. The liquid silicone material should be poured at a depth of at least 0.5 cm above the highest point of the model surface. If the layer is too thin, the mold can tear easily.

Step 6: Demolding the Mold

Under normal circumstances, platinum-cure silicone rubber cures within the specified demold time at room temperature (25℃/77°F). Higher temperatures will result in shorter curing times, while lower temperatures may require more time for curing to complete.

After the specified curing time has elapsed, the outer surface of the mold should feel hard and dry. If the mold's hardness does not change after a period of time, it is usually safe to remove or demolded.

  • Why can't the silicone I use be cured, even heating can't solve it.
    Cure inhibition can occur with platinum-curing silicone, and it depends on the material in contact with the silicone. Surface compounds that contain water, sulfur, nitrogen compounds, organometallic or phosphate compounds may inhibit the curing process. Cure inhibition is characterized by a gummy or sticky appearance of the silicone at the interface between the silicone and the offending substrate.
    Helpful (7) Not Helpful (20) Reply
  • Can I use this rtv silicone to make silicone rings? Or is this just a mold used to make cast things?
    Our RTV-2 liquid silicone material is usually used to make molds. Since it tends to attract dust, it is not very suitable for making silicone rings.
    Helpful (21) Not Helpful (8) Reply
  • When using non-sulfur oil based clays, I have had issues curing the silicone. Can I cover the non-sulfur oil based clay with a release agent to solve the curing problem? Is there any good solution?
    Non-sulfur oil-based clays can sometimes interfere with the curing process of silicones. This is because the clay may contain sulfur, which can react with the silicone and prevent it from curing properly. Mold release agent is not a good solution, as it will not prevent the sulfur from reacting with the silicone. The best solution is to use a clay that does not contain sulfur, or to prime the clay before pouring in the liquid silicone.
    Helpful (29) Not Helpful (30) Reply
  • Could I use liquid epoxy coloring in conjunction with this product?
    Using liquid epoxy coloring is not recommended, as it may adversely affect the curing process of platinum-cured silicone. For best results, please use a special silicone pigment designed for silicone rubber.
    Helpful (11) Not Helpful (10) Reply
  • Is it liquid or is it like plasticine? In other words, is it suitable for making molds, or is it used to fill molds?
    It is liquid and is used to create a silicone mold.
    Helpful (8) Not Helpful (79) Reply
  • Can this silicone material be used to make a mold and then use it to make silicone products?
    Yes, you can make a mold with our platinum-cured silicone and use it to make silicone items. However, there are some pre-treatment steps that you need to follow. Please contact our customer support team for detailed directions.
    Helpful (9) Not Helpful (19) Reply
  • I am wondering if anyone has used platinum-cured silicone as a base coat, then applied tin-cured silicone to bulk out the rest of the mold space for strength. I am wondering if the tin-cured silicone would effectively bond to the platinum-cured silicone.
    It's worth noting that tin-cure silicone and platinum-cure silicone don't form a strong bond with each other. This is mainly due to the fact that tin-cured silicone tends to shrink more than platinum-cured silicone, making it unsuitable for certain applications where a seamless and durable bond between the two is required.
    Helpful (8) Not Helpful (8) Reply
  • I have been searching for a way to create a life-sized, 3D life-like mold of peach using resin. Would this work?
    Our rtv-2 silicone material can capture very fine details, so it will work well for your needs.
    Helpful (7) Not Helpful (6) Reply
  • I am planning to make a mold for soft bait fishing lures. Would this be a suitable material for pouring plastisol into?
    Yes, you can use our addition cured silicone to make silicone molds for soft baits and fishing lures. When casting plastisol, it is recommended to apply a release agent to avoid sticking mold separation difficulties.
    Helpful (11) Not Helpful (10) Reply
  • Why has the liquid silicone I used not cured in over 24 hours?
    This type of silicone is an addition-cure silicone that contains a platinum catalyst. The primary reason why this type of silicone has curing inhibition is that your master mold contains acid or alkali substances. UV resins for 3D printing materials are typical cases. In addition, temperature may also affect the curing of silicone.
    Helpful (11) Not Helpful (9) Reply
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