Platinum Cure Silicone Rubber for Professional Mold Making
A cured sample of our platinum silicone passed SGS testing for total extractives (distilled water) per FDA 21 CFR 177.2600 (2017). The report applies only to the tested pink cured sample and test conditions. See our test report and scope.
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Platinum-cure silicone may be inhibited by sulfur-containing clay, latex gloves, tin-cure silicone residue, amines, certain epoxy curing agents, and unsealed SLA, LCD, or DLP resin prints. Run a small compatibility test before full use.
View our SGS test report and material documentation on the Quality & Compliance page.
1. Description
What Is Platinum Silicone for Mold Making
Platinum cure silicone is a professional mold making silicone used to produce flexible, durable, and dimensionally stable molds for repeated casting applications. Review BK-A platinum-cure silicone in Shore A5 and A15 when comparing material options for a mold-making project.
BK Silicone BK-A Series is a two-component addition-cure silicone elastomer. BK-A05 and BK-A15 are also the materials used for our finished silicone molds. With a 1:1 mixing ratio by weight, low initial viscosity, natural self-degassing behavior, and room-temperature curing, it supports mold-production work with standard mixing and pouring equipment.
BK Silicone BK-A Series is a high-performance, two-component platinum-cure silicone elastomer that cures at room temperature via an addition-catalyzed reaction.
2. Advantages of Platinum Silicone for Mold Making
- Platinum-catalyzed addition cure system: Clean curing at room temperature with no by-products.
- Simple 1:1 mixing ratio by weight: Ensures consistent and repeatable processing.
- Low initial viscosity: Good flowability enables easy pouring and natural self-degassing behavior.
- Low shrinkage (≤0.1%): Provides excellent dimensional stability after curing.
- High elasticity & Tear strength: Supports reliable demolding and long mold service life.
- Excellent Chemical Resistance: Compatible with polyurethane, epoxy, polyester resins, wax, and gypsum.
3. Applications of Platinum Silicone in Mold Production
BK Silicone BK-A Series is a professional silicone for mold making and casting applications where flexibility, dimensional stability, and reliable demolding are required.
Candle Molds
Silicone molds for pillar candles, container candles, and decorative candle designs requiring clean surface finish and stable demolding.
Plaster & Aroma Stone
Casting molds for gypsum, plaster, and aroma stone products with repeated production cycles.
Concrete & Cement Molds
Flexible molds for small concrete items, architectural details, and decorative cement components.
Creative & Character Molds
Silicone molds for figurines, decorative objects, and custom creative designs with complex geometries.
Fondant & Cake Decorating
Molds for sugar paste, fondant, and cake-decoration elements where fine detail reproduction is required. A cured sample of our platinum silicone passed SGS testing for total extractives (distilled water) per FDA 21 CFR 177.2600 (2017). The report applies only to the tested pink cured sample and test conditions.
Lightweight Mold Designs
Thin-wall and reduced-material molds optimized for cost efficiency while maintaining structural stability.
4. Processing Notes
- Batch Consistency: Always use Part A and Part B from the same production batch. If components from different batches must be mixed, conduct a small-scale test first.
- Compatibility Testing: A preliminary test is strongly recommended to confirm compatibility with specific substrates, mold materials, or additives prior to large-scale production.
- Mixing & Curing Conditions: For optimal performance, mix and cure at an ambient temperature of 20–30 °C (68°F–86°F) with relative humidity below 50%.
- Minimum Application Temperature: Do not process below 15 °C (59°F). Lower temperatures may significantly slow curing or result in incomplete crosslinking.
CURE INHIBITION WARNING
Platinum-cure silicone systems are sensitive to certain contaminants. Ensure all tools, containers, and model surfaces are clean. Avoid contact with materials containing:
- Sulfur (e.g., sulfur-based clays, latex gloves)
- Tin compounds (condensation-cure silicone rubbers)
- Amines (certain epoxy systems and curing agents)
- Unsealed LCD / DLP 3D printed resins
Contact with these materials may result in surface tackiness or incomplete curing. A small test cure is always recommended.
5. Safety Precautions
Under normal storage and handling conditions, this product is stable and does not present unusual hazards. Standard industrial hygiene and safety practices should be followed at all times.
- General: Keep out of reach of children. Use only as intended.
- Skin Contact: Wash thoroughly with soap and water after contact. Remove contaminated clothing if necessary.
- Eye Contact: Rinse immediately with clean water for at least 15 minutes. Seek medical attention if irritation persists.
- Inhalation: Ensure adequate ventilation during mixing and processing.
- Ingestion: Do not induce vomiting. Rinse mouth and seek medical attention promptly.
*For detailed health, safety, and regulatory information, please refer to the Safety Data Sheet (SDS).
6. Storage & Shelf Life
| Physical Property | BK-A05 | BK-A15 |
|---|---|---|
| Unvulcanized Physical Properties @ 23°C/73°F | ||
| Physical State | Liquid | Liquid |
| Form | Viscous | Viscous |
| Odor | No discernible odor | No discernible odor |
| Part A Color | Translucent | Translucent |
| Part B Color | Translucent | Translucent |
| Part A Viscosity, mPa·s | 1,500 | 1,500 |
| Part B Viscosity, mPa·s | 2,500 | 3,500 |
| Specific Gravity, g/cm³ | 1.03-1.05 | 1.03-1.05 |
| Part A and Part B mixed @ 23°C/73°F | ||
| Mix Ratio by Weight (A:B) | 1:1 | 1:1 |
| Working Time, Minutes | 30±5 min | 30±5 min |
| Curing Time, Hours | 4±1 hrs | 4±1 hrs |
| Typical Properties of Cured Rubber @ 24 Hrs 23°C/73°F | ||
| Hardness, Shore A Durometer | 5 | 15 |
| Tear Strength, N/mm | 10 | 15 |
| Tensile Strength, MPa | 2.5 | 2.0 |
| Elongation, % | 680 | 500 |
| Shrinkage, % | ≤0.1 | ≤0.1 |
| Heat Resistance, °C (°F) | 250 (482) | 250 (482) |
Typical values from BK-A Series TDS V2.0, revised 2026-08-08; not a sales specification. Heat resistance is a typical material capability, dependent on exposure time, load, casting medium and mold geometry. Validate the actual process before use.
How to Use Platinum Silicone for Mold Making
BK Silicone BK-A Series is a two-part platinum cure RTV-2 silicone designed for professional mold making. It is mixed at 1:1 by weight and offers low initial viscosity, natural self-deaeration, fast room-temperature curing, and low shrinkage, making it suitable for candle, plaster, concrete, creative, and selected fondant mold applications.
Prepare the master pattern
Make sure the model surface is clean, dry, and securely fixed inside a leak-free mold box. For best results, the master should be free from dust, oil, and unknown surface contamination. A small compatibility test is recommended before full production, especially for new substrates or additives.
Check working environment
Recommended mixing and curing conditions are 20–30°C (68°F–86°F) with relative humidity below 50%. Do not process below 15°C (59°F), as low temperature may slow curing or cause incomplete crosslinking.
Measure Part A and Part B
Mix Part A and Part B at 1:1 by weight. Always use components from the same production batch whenever possible. If material from different batches must be combined, perform a small test first.
Mix thoroughly
Stir slowly and evenly until the material is fully uniform. Be sure to scrape the sidewall and bottom of the container during mixing. At 23°C / 73°F, the typical working time is 30 ± 5 minutes, so prepare tools and molds before mixing.
Degassing
BK-A05 and BK-A15 have low initial viscosity and natural self-degassing behavior. For deep cavities, highly detailed patterns, or critical surface finish, vacuum degassing is still recommended for better consistency.
Pour slowly
Pour the silicone in a thin, steady stream from one corner of the mold box and allow it to flow around the master naturally. This helps reduce trapped air and improves detail reproduction.
Room temperature cure
Under standard conditions of 23°C / 73°F, the typical cure or demolding time is 4 ± 1 hours. Full cured properties are referenced after 24 hours at the same temperature. Do not move or demold too early.
Demold carefully
Once cured, remove the silicone mold slowly and support thin sections. BK-A05 offers very high elongation and softness, while BK-A15 provides higher hardness and tear strength for structured molds.
Clean and store properly
Store unused material at 15–25°C (59°F–77°F) in a cool, dry place. Keep containers tightly sealed. Shelf life is 12 months in unopened original packaging. Reseal immediately and handle with clean tools.
Cure Inhibition Warning
Platinum cure silicone may be inhibited by contaminants such as sulfur, tin-cure silicone residues, amines, and unsealed LCD/DLP 3D printed resins. These may cause surface tackiness or incomplete cure. Always perform a small test when material compatibility is uncertain.
Frequently Asked Questions
What is BK-A Series platinum-cure silicone used for?
It is a two-part mold-making silicone used for flexible molds for candles, plaster, aroma stone, concrete or cement, and custom decorative casting.
What is the mixing ratio for BK-A05 and BK-A15?
Both grades use a 1:1 mixing ratio by weight. Accurate weighing and thorough mixing are important for a proper cure.
What can inhibit platinum-cure silicone?
Sulfur-based clay, latex gloves, tin-cure silicone residues, certain amines, and unsealed LCD or DLP resin prints may cause tackiness or incomplete curing. Run a small compatibility test when the surface is uncertain.
Does BK-A Series always need vacuum degassing?
Not always. BK-A05 and BK-A15 have low initial viscosity and natural self-degassing behaviour. Vacuum degassing is still recommended for deep cavities, complex details, or a critical surface finish.
How do I choose between BK-A05 and BK-A15?
BK-A05 is softer and more flexible, while BK-A15 is harder and has higher tear strength for molds that need more structure. Confirm the grade against the mold geometry, casting material, and production requirements.
Why Choose BK Silicone for Mold-Making Silicone
- BK-A05 and BK-A15 are the materials used for our finished silicone molds.
- Standard packs: 1 kg / 8 kg / 40 kg total weight, with Part A and Part B supplied in equal weights.
- Applications include candle, plaster, resin, and concrete mold making.
- OEM and private-label supply are available.
- Technical support is available for mold-production projects.
- International shipping is available by courier, air freight, or sea freight.
For mold-making silicone selection, contact BK Silicone with the mold geometry, intended casting material, and process conditions.
