Seeking High-Transparency Silicone?

When a client came to us with a requirement for an 8mm thick, 25×25mm square silicone part that needed to be optically clear, they brought a common pain point: standard solid silicone parts at this thickness always turned out milky and translucent, which was completely unacceptable for their application.

If you’ve ever struggled with getting a thick silicone part to be truly crystal clear, you’re not alone. The truth is, solid rubber silicone has a fundamental transparency limit that makes optical-grade clarity at 8mm thickness nearly impossible. But with Liquid Silicone Rubber (LSR) technology, we solved this problem perfectly. In this case study, we’ll break down the challenges, our solutions, and the final results.

Comparison of Little Duck Made of Liquid Silicone (left) and Solid Silicone (right)

The Challenge: Why Solid Silicone Could Not Meet the Demand

Most common transparent silicone parts are made of solid silicone rubber (HCR).

However, solid silicone has a natural limit in transparency:

• It becomes milky or cloudy when thickness exceeds 5mm

• Cannot achieve optical-level clarity

• Easy to have flow marks, bubbles, and inconsistent transparency

For an 8mm-thick part, solid silicone simply cannot meet the client’s visual standard.

Even with high-transparency solid silicone raw materials, it is physically impossible to achieve fully crystal-clear transparency after compression molding.

Restricted by its inherent molecular crystal structure, high-transparent solid silicone can only present hazy translucent effect. For parts that require ultra-clear, crystal finish, LSR liquid silicone injection molding is the only feasible solution.

Solid Silicone Compression Molding Process

Our Solution: Liquid Silicone Rubber (LSR) + High-Polish Mold

1) Material Selection

We recommended liquid silicone rubber (LSR) with optical-grade .

LSR offers much higher clarity, especially for thick sections.

2)Mold & Production

High-transparency parts have extremely high requirements for molds:

• High-quality mold steel

• Mirror polishing + plating on cavity surface

• Optimized venting system to avoid bubbles and short shots

3) Quality Control

• Dust-free production environment

• Strict raw material inspection

• 100% visual inspection for transparency & appearance

Final Result

• Successfully achieved crystal clear appearance at 8mm thickness

• No milky, cloudy, or foggy issues

• Stable dimensions and consistent quality in mass production

• Fully met the client’s requirements for transparency and performance

Little Duck Made of Liquid Silicone

Professional Advice for Your Project

If you need:

• Transparency over 5mm thickness

• Optical-level clear appearance

• Food-grade or medical-grade requirements

We strongly suggest LSR liquid silicone molding.

Our team can provide material suggestions, mold solutions, and mass production support.

Contact Us for a Custom Solution

If you have a design for high-transparency silicone parts, please feel free to send us your 2D/3D drawings for a free quotation and professional advice.