Transparent / Clear Silicone O-rings
Manufacturer & Custom Solutions

Transparent / Clear Silicone O-rings

Clear silicone O-rings let you see fluid levels, contamination or wear without disassembling your equipment. ZSR Silicone molds these from platinum-cured VMQ for the best optical clarity. Popular in medical devices, laboratory equipment and food processing.

  • Colors: Black, White, Transparent, Pantone Match, Custom
  • Color Compounded Throughout (not surface coated)
  • Visual Identification & Branding Options
  • MOQ: Flexible / Low MOQ Support
  • Lead Time: Prototype in 2-5 Days
  • Certifications: FDA, LFGB, ISO 9001, ROHS, REACH
  • Batch Consistency: Color-matched from lot to lot
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FDA 21 CFR 177.2600

Rubber Articles Intended for Repeated Use

LFGB 30&31

EU Food Contact Materials

USP Class VI / ISO 10993

Biocompatibility of Medical Devices

RoHS / REACH

Environmental Compliance

UL 94

Flammability of Plastic Materials

More

Built to Your Exact Spec

Custom Silicone O-ring Options

ImageProductTypeShort InfoAction
ISO 3601 Metric Silicone O-Rings ISO 3601 Metric Silicone O-Rings Standard & Size Metric silicone O-rings manufactured to ISO 3601 dimensions. Fits international equipment groove standards. View Details
ISO 6149 Metric Silicone O-Rings ISO 6149 Metric Silicone O-Rings Standard & Size Metric O-rings designed for hydraulic and pneumatic fluid power sealing applications under ISO 6149 standards. View Details
BS 1806 Silicone O-rings BS 1806 Silicone O-rings Standard & Size British Standard inch-size silicone O-rings. Common in UK and Commonwealth industrial equipment. View Details
DIN 3771 Silicone O-rings DIN 3771 Silicone O-rings Standard & Size German metric standard O-rings for hydraulic and pneumatic sealing in European machinery. View Details
Custom Molded Silicone O-rings Custom Molded Silicone O-rings Standard & Size Custom-shaped silicone O-rings molded to your exact drawing or sample. No standard size limitations. View Details
AS568 Silicone O-rings AS568 Silicone O-rings Standard & Size Inch-size silicone O-rings that follow the AS568 standard. Widely used in North American machinery and hydraulic systems. View Details
AN6227 Silicone O-rings AN6227 Silicone O-rings Standard & Size Aerospace-standard O-rings with small cross-section. Used in aviation and military-grade sealing. View Details
AN6230 Silicone O-rings AN6230 Silicone O-rings Standard & Size Aerospace-standard O-rings specified under AN6230 for aviation and military-grade sealing. View Details
JIS B2401 Silicone O-Ring JIS B2401 Silicone O-Ring Standard & Size Japanese industrial standard O-rings commonly used in Asian-manufactured machinery and automotive equipment. View Details
FDA Food Grade Silicone O-Rings FDA Food Grade Silicone O-Rings Grade Food-safe silicone O-rings compliant with FDA regulations. Safe for repeated food contact. View Details
Industrial Grade Silicone O-ring Industrial Grade Silicone O-ring Grade General-purpose silicone O-rings for industrial sealing. Cost-effective with reliable performance. View Details
Medical Grade Silicone O-ring Medical Grade Silicone O-ring Grade Biocompatible silicone O-rings for medical devices. Passes USP Class VI and supports sterilization. View Details
Oil-Resistant / Fuel-Resistant Silicone O-Rings Oil-Resistant / Fuel-Resistant Silicone O-Rings Special Function Modified silicone O-rings that resist swelling in oils, fuels and petroleum-based fluids. View Details
Metal Detectable Silicone O-Rings Metal Detectable Silicone O-Rings Special Function Food-safe silicone O-rings with metal-detectable additives. Protects production lines from contamination. View Details
High Temperature / Heat Resistant Silicone O-Rings High Temperature / Heat Resistant Silicone O-Rings Special Function Silicone O-rings that stay flexible at temperatures above 200°C. For ovens, engines and furnaces. View Details
VMQ Silicone O-Rings VMQ Silicone O-Rings Materials Heat and cold-resistant silicone O-rings for food, medical, automotive, and industrial applications. View Details
Fiberglass Reinforced Silicone O-rings Fiberglass Reinforced Silicone O-rings Materials High-strength silicone O-rings reinforced with fiberglass fabric. Withstands extreme heat and pressure. View Details
HCR / HTV / Solid Silicone Rubber O-rings HCR / HTV / Solid Silicone Rubber O-rings Materials Durable solid silicone rubber O-rings made by compression molding. The standard choice for general sealing. View Details
Liquid Silicone Rubber (LSR) O-rings Liquid Silicone Rubber (LSR) O-rings Materials Injection-molded liquid silicone rubber O-rings with tight tolerances and clean surfaces. Ideal for high-volume production. View Details
Platinum Cured Silicone O-rings Platinum Cured Silicone O-rings Materials Ultra-clean silicone O-rings cured with platinum catalyst. Lower extractables for food and medical use. View Details
Fluorosilicone (FVMQ) O-rings Fluorosilicone (FVMQ) O-rings Materials Fuel and oil-resistant silicone O-rings for aerospace, automotive and chemical applications. View Details
Transparent / Clear Silicone O-rings Transparent / Clear Silicone O-rings Color See-through silicone O-rings for visual inspection and clean-looking medical or food equipment. View Details
Black / White Silicone O-Rings Black / White Silicone O-Rings Color Standard black and white silicone O-rings. The most common colors for industrial and food-grade applications. View Details
Pantone Colors Silicone O-rings Pantone Colors Silicone O-rings Color Silicone O-rings in any Pantone color for branding, color-coding or aesthetic requirements. View Details
Custom Colors Silicone O-rings Custom Colors Silicone O-rings Color Silicone O-rings matched to your exact color sample or specification. View Details

Transparency Grades

At ZSR Silicone Parts, we do not just make "clear" silicone. We offer three levels of transparency so you can match the grade to your application needs and budget.

Grade

Description

Light Transmission

Best For

Production Method

Translucent

Milky or foggy appearance. You can see light through it but not shapes.

40% – 70%

General industrial seals, diffusers, light covers, cost-sensitive projects

Standard platinum-cured HCR or LSR

High Transparent

Clear like a frosted window. You can see shapes and colors through it.

70% – 90%

Food equipment, medical tubing connectors, consumer electronics, display seals

Platinum-cured LSR with vacuum deaeration

Optical Grade

Crystal clear like glass. Minimal haze, minimal bubbles.

90% – 95%+

Optical devices, sensors, camera housings, LED lenses, precision instruments

Specialized platinum-cured LSR in cleanroom conditions

What Affects Transparency at ZSR
  • Curing system: Platinum curing is essential. Peroxide curing leaves haze and yellowing.
  • Filler content: Transparent silicone uses little or no reinforcing filler. This makes it softer and slightly weaker than filled grades.
  • Bubble control: Air bubbles trapped during mixing ruin clarity. ZSR uses vacuum mixing and controlled injection to remove bubbles.
  • Mold surface: The mold must be highly polished. Any scratch on the mold transfers to the O-ring surface.
  • Post-cure: Over-baking can cause yellowing. ZSR controls time and temperature precisely.
Important Note

True optical-grade transparency in silicone is difficult to achieve in thick cross-sections. For O-rings with a wire diameter over 5 mm, some haze is normal even in high-transparent grades. If you need perfect clarity in a large O-ring, contact ZSR and we will review the design.

Clear vs Colored Silicone

Clear silicone is not just colored silicone without pigment. It requires a completely different production approach.

Feature

Colored Silicone (Black, White, Red, etc.)

Clear / Transparent Silicone

Curing System

Peroxide or platinum cured

Almost always platinum cured

Purity

Standard — fillers and pigments added

Higher — minimal fillers, no pigments

Production Environment

Standard clean workshop

Cleaner — dust and particle control is critical

Hardness Range

10 – 90 Shore A

Usually 20 – 60 Shore A (higher hardness reduces clarity)

Tensile Strength

4 – 12 MPa

3 – 8 MPa (less filler means slightly weaker)

Temperature Range

-60°C to +230°C

-60°C to +200°C (some high-temp stabilizers cause yellowing)

UV Resistance

Good — darker colors resist UV better

Fair — clear silicone can yellow slightly over years in direct sun

Cost

Standard

Higher — due to purer raw materials and stricter process control

Lead Time

Standard stock available

Longer — may need custom mixing and special mold prep

Why Clear Silicone Costs More

At ZSR, clear silicone requires:

Purer raw materials

The base polymer must have very low impurity levels.

Vacuum mixing

Extra equipment and time to remove bubbles.

Platinum curing

More expensive than peroxide curing.

Polished molds

Higher mold maintenance cost.

Stricter inspection

Every part is checked for haze, bubbles, and contamination.

When to Choose Clear vs Colored

Choose clear when

You need to see fluid flow, detect contamination, allow light through, or match a clean aesthetic.

Choose colored when

You need UV resistance, the lowest cost, or the O-ring hides dirt and wear.

Best Applications for Clear O-rings

ZSR's transparent silicone O-rings are used in applications where visibility, purity, or light transmission matters.

Industry

Application

Why Clear Silicone Works

Medical Devices

IV connectors, respiratory masks, blood analyzers, surgical drains, catheter seals

Doctors and nurses can see fluid flow and air bubbles. Contamination is visible instantly.

Food & Beverage

Water dispenser seals, juice machine gaskets, beverage tubing connectors, sight glass seals

Consumers and inspectors can see that the seal is clean. No hidden dirt or mold.

Laboratory Equipment

Bioreactor seals, chromatography gaskets, filtration system O-rings, pipette seals

Researchers can observe reactions and fluid levels without disassembling equipment.

Electronics & Optics

Camera housing seals, sensor windows, LED display gaskets, fiber optic connectors

Light passes through without blocking or diffusing. Protects sensitive optics while sealing.

Consumer Products

Aquarium equipment, cosmetic packaging, baby bottles, water bottles

Clean, premium appearance. Parents and consumers trust visible, transparent materials.

Pharmaceutical

Vial seals, mixing tank sight glasses, liquid drug delivery systems

Meets purity standards while allowing visual inspection of contents.

What Is Transparent / Clear Silicone?

Transparent silicone is silicone rubber that you can see through. Unlike standard silicone that is opaque or colored, clear silicone allows light to pass through with minimal scattering. It is made from the same base polymer as all silicone rubber — polydimethylsiloxane — but with far fewer additives that block light.

How ZSR Makes Clear Silicone

At ZSR Silicone Parts, making transparent silicone requires extra care at every step:

  • Raw Material Selection: We start with a high-purity silicone base that has very low natural color. Lower-grade polymers have a slight yellow or gray tint that cannot be removed.
  • No Pigments, Minimal Fillers: Standard silicone uses reinforcing fillers like fumed silica to add strength. These fillers are white and block light. For transparent grades, we use special treated fillers in very small amounts, or we use no fillers at all for optical grades.
  • Platinum Curing Only: Peroxide curing creates by-products that make the rubber hazy or yellow. At ZSR, all transparent silicone uses platinum curing. This is more expensive but essential for clarity.
  • Vacuum Mixing: During mixing, air bubbles get trapped in the compound. In colored silicone, these bubbles are hidden. In clear silicone, every bubble is visible. ZSR mixes the compound under vacuum to pull out trapped air.
  • Polished Molds: The mold surface must be mirror-smooth. Any roughness on the mold creates a frosted effect on the O-ring surface.
  • Controlled Post-Cure: After molding, the parts are baked in a clean oven to stabilize the material. If the temperature is too high or the time is too long, the silicone turns yellow. ZSR controls this precisely.
Key Properties of Transparent Silicone
  • Temperature Range: -60°C to +200°C continuous. Short-term peaks to +230°C. High-temperature exposure over time can cause slight yellowing.
  • Hardness: 20 to 60 Shore A at ZSR. Very soft clear silicone (10–20 Shore A) is possible but difficult to keep bubble-free.
  • Light Transmission: 70% to 95% depending on grade and thickness.
  • Elasticity: Excellent — even with minimal fillers, clear silicone stays very flexible.
  • Chemical Purity: Very high. No pigments, no odor, no taste. Ideal for medical and food contact.
  • UV Stability: Fair. Clear silicone does not have the UV protection of carbon black. Long-term direct sunlight can cause slight yellowing. For outdoor use, ZSR recommends adding a small amount of UV stabilizer, which may reduce clarity slightly.
Limitations to Know
  • Weaker than filled silicone: Because clear silicone uses little or no reinforcing filler, it has lower tear strength and tensile strength than standard VMQ. It is not the best choice for high-pressure or high-wear applications.
  • Yellowing over time: Even the best clear silicone can develop a slight yellow tint after years of heat exposure. This is normal and does not affect sealing performance.
  • Not suitable for fuels or oils: Like all standard silicone, clear silicone swells in hydrocarbons.
  • Dust and fingerprints show easily: The clean look of clear silicone also means every speck of dust or fingerprint is visible. Handling and packaging require extra care.
Summary

Transparent silicone is the purest, cleanest form of silicone rubber. It seals as well as colored silicone, but it adds something extra: visibility. Whether you need to see fluid flow in a medical device, show purity in a food machine, or let light through an optical seal, clear silicone is the right choice. At ZSR, we produce transparent silicone O-rings in translucent, high-transparent, and optical grades, with the process control and inspection needed to deliver true clarity every time.