Post Curing: The Key to Unlocking Superior Quality and Safety in Silicone Products

In today's fast-evolving materials landscape, silicone stands out for its exceptional weather resistance, biocompatibility, and sealing performance. From automotive and electronics to healthcare and food packaging, silicone has become an essential component in critical applications. However, to elevate silicone products from qualified to excellent, manufacturers must go beyond traditional processing methods. Post curing technology is the game-changing step that ensures maximum performance, product safety, and compliance.

What Is Post Curing Technology?

Post curing—also known as secondary curing—is a heat treatment process applied after the initial vulcanization (or primary cure) of silicone products. It is especially important for both Liquid Silicone Rubber (LSR) and High Temperature Vulcanized (HTV) silicone products.

Understanding the Curing Process

• 1. Primary Curing: The initial heat-induced chemical crosslinking that transforms silicone from a soft, paste-like material into a flexible, solid elastomer.

• 2. Post Curing: A secondary heat treatment—typically in a well-ventilated oven or under inert gas conditions—that removes volatile residues and enhances material properties through further crosslinking.

Typical Post Curing Parameters

Why Post Curing Technology Matters?

1. Eliminates Odors and Improves User Experience

During initial production, silicone may retain residues from additives and incompletely reacted curing agents, leading to unwanted odors. Post curing drives additional chemical reactions that reduce volatile organic compounds (VOCs) and eliminate these odors at the molecular level.

Technical Insight: At 180–220°C, unreacted peroxides and siloxane chains undergo further crosslinking, forming a tighter 3D network that locks in small molecules.

Application Example: In baby-grade silicone tableware, post curing reduces VOC content to below 0.5%, far under the EU REACH regulatory limit—eliminating the "rubbery smell" and ensuring a pure, safe dining experience.

2. Ensures Compliance with LFGB and VOM Testing

For food-contact silicone products, post curing technology is essential to meet international safety standards such as LFGB (Germany) and total volatile organic matter (VOM) requirements.

Safety Upgrade:

Removes 95%+ of residual curing agents (e.g., DCP) and cyclic siloxanes.

Controls total migration levels (OML) below 1 mg/dm², preventing harmful leaching into food.

Performance Boost:

• ◆ Increases crosslinking density by 30–50%.

• ◆ Enhances Shore hardness precision (±2A).

• ◆ Reduces compression set below 8%.

• ◆ Passes rigorous thermal aging tests (200°C for 4 hours).

According to international certification data, only ~60% of untreated silicone products pass LFGB tests, while post-cured products reach a 99.2% compliance rate—a critical differentiator for entering high-end EU and US markets.

3. Enhances Durability and Product Lifespan

As consumer demands rise and regulations tighten, post curing technology has evolved from an optional step to a quality benchmark for premium silicone products.

Take the silicone optical lenses for example:

• 1. Post curing is vital to maintaining optical clarity and dimensional stability.

• 2. Uncured residues can lead to reduced light transmittance, inconsistent refractive indices, and accelerated degradation.

• 3. Post curing boosts light transmittance up to 98.5%, with yellowness index held below 0.5, ensuring long-term optical performance even in harsh environments like LiDAR and UV lighting systems.

• 4. Uncured micro-stresses can increase glare by 200% and distort optical uniformity. Post curing eliminates these issues, delivering stable, high-precision components.

Post Curing Technology: A Vital Step to Achieve High-End Quality

From precision components in electronics and automotive systems to household and food-grade silicone products, Hopewell leverages advanced post curing technology to deliver silicone solutions that are safer, more reliable, and more durable.

Each degree of temperature control, every hour of thermal refinement, reflects our commitment to the principle: uncompromising quality and safety without boundaries. At Hopewell, we continue to drive innovation in silicone molding and processing—empowering our clients to meet the most demanding standards in medical, optical, and industrial applications. Explore Hopewell's post curing capabilities and unlock the full potential of high-performance silicone.

Frequently Asked Questions

Q1: Is post curing always necessary for silicone products?
A1: It is essential for food-grade, medical, and optical silicone products to ensure safety and performance.

Q2: Does post curing increase production cost?
A2: Slightly, but it significantly enhances product value and market acceptance.

Q3: Can Hopewell support custom post curing specifications?
A3: Yes, we provide tailored post-curing schedules based on your product geometry and application requirements.