"A Comprehensive Guide to Selecting Silicone Viscosity for Casting, Brushing, and Calendering"
Viscosity is a core specification for liquid silicone, directly shaping mold efficiency, detail replication and mold lifespan. A mismatched viscosity for casting, brushing or calendering causes poor details, low productivity and material waste. Below is a concise guide from Jiajinghong for precise material matching.
1. Casting: Low Viscosity for Flow & Degassing
Casting relies on gravity filling, with the highest fluidity demand. Recommended: 3,000–10,000 mPa·s
- 3,000–5,000 mPa·s: For fine-pattern precision parts (reliefs, jewelry, prototypes), penetrates micron-level textures and degasses thoroughly.
- 5,000–10,000 mPa·s: General-purpose for small-to-medium crafts, gypsum parts and food molds.
⚠️ Avoid silicone above 35,000 mPa·s — it causes incomplete filling, trapped bubbles and high scrap rates.
2. Brushing: Medium-High Viscosity for Sag Resistance
Brushing builds layers manually, requiring good wall-hanging performance. Recommended: 15,000–30,000 mPa·s (thixotropic formula)
- 15,000–20,000 mPa·s: For small/irregular parts and sculptures, easy application with tight interlayer bonding.
- 20,000–30,000 mPa·s: For large/vertical projects (columns, cement components), builds thick layers with gauze reinforcement.
⚠️ Too low viscosity causes sagging and rework; too high creates application resistance and delamination.
3. Calendering: High-Viscosity Paste for Uniform Film
Calendering produces continuous sheets via multi-roll shearing. Recommended: ≥50,000 mPa·s high-thixotropy paste
It spreads evenly under shear and recovers consistency fast, keeping thickness tolerance within ±0.05 mm. Ideal for thermal pads and silicone rolls.
⚠️ Too low viscosity causes roller sticking; too high leads to trapped bubbles and degraded mechanical performance.
Core Selection Principles
- Match the process first: low for casting, medium-high for brushing, high for calendering.
- Finer patterns call for lower viscosity; larger/heavier parts need higher viscosity for strength.
- Winter low temperatures raise viscosity — choose slightly lower nominal grades or control working temperature.
Jiajinghong New Materials offers liquid silicone covering 3,000–100,000 mPa·s, with customizable viscosity, hardness and pot life. We provide free samples and technical guidance to reduce your mold-making costs and improve product yield.
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