TIPS WITH TONY: Shedding Light on Clear Materials

Designing luminaires or lenses with clear materials? Our tip this week looks at the material selection and surface finishes available for prototyping and low-volume production of lighting applications.

Prototype built in clear WaterShed XC 11122 material with stereolithography.

Additive Manufacturing
If you haven’t considered using additive manufacturing (3D printing) for your lens design, you may want to check it out. Proto Labs offers stereolithography (SL) with three options for clear parts.

  • Somos WaterShed XC 11122 — ideal for lens and high-humidity applications
  • 3D Systems Accura 60 (10 percent glass-filled) — creates a clear part with slight blue tint and high stiffness
  • 3D Systems Accura 5530 — high temperature resistance, suitable for under-the-hood applications

TIPS WITH TONY: LSR Offers Design Flexibility

There are many reasons why you should be looking at liquid silicone rubber (LSR) — I’ll highlight a few big ones in order to get you thinking about this versatile thermoset.

For a deeper dive into LSR and how it’s used in the lighting industry, please attend my free tech talk webinar hosted by Tech Briefs.

LSR Molding
LSR parts are formed in process similar to that of conventional plastic injection molding with one main difference. LSR is a thermoset material that compounds two liquids together, which is then heat cured in the mold to produce a part. The material delivery system is cooled and only the mold is heated. This is unlike thermoplastic molding, which begins with the melting of plastic pellets that are injected into a heated mold.

Optical LSR is highly flexible and can replace glass in many lighting applications.

LSR Advantages
LSR parts are strong, elastic, chemical resistant, serializable and biocompatible, and have a range of operating temperatures. The benefits of LSR lend itself well to the automotive, medical and lighting industries where gaskets, seals and lighting lenses are frequently used.

LSR parts have a very good temperature resistance, ranging between -49°F to 392°F; they are non-yellowing, UV stable and optical LSR has up to 94 percent light transmission; they offer good vibration control and offer up to 400 percent flexibility along with excellent part memory.

The chart pretty much speaks for itself when comparing LSR to PC, PMMA and glass when looking at replacing the traditional materials with LSR.

Design Flexibility
Traditional thinking of part design needs to be considered, but many can be broken:

  • Part thicknesses greater than 1 in. and less than 0.020 in. are achievable with little to no concern of any unsightly sinks or internal voids.
  • No ejector pins are used to remove parts from the mold as they are all hand-removed.
  • Gates are nearly invisible, barely thicker than flash. LSR flows like water, so the gate needs to be very shallow, but wide.
  • Negative draft angles or increased undercuts are a possibility with up to 400 percent part flexibility and part memory.
  • Ability to fill fine details or voids.
  • Ability to combine components reducing number of parts to assemble, e.g., combining a lens and seal for lighting applications.

For more information on LSR, please download our white paper or listen in to my tech talk presentation mentioned at the top of the tip. You can also visit our website at or contact one of our customer service engineers at or 877.479.3680 with additional questions on any of our services.

Just Press Play for a Tour of Injection Molding

Our short video series continues with a look at the three different injection molding processes available at Proto Labs. See how we manufacture plastic, metal and liquid silicone rubber prototypes and low-volume production parts so fast.

Use CNC machining more? Take a spin through one of our high-speed mills. And if you’re curious as to how we’re able to turn your 3D CAD model into real parts in only a few days, check out our Art to Part video.

14 Reasons Why Optical LSR is Good for Lighting Applications

As LEDs increasingly supplant metal filaments in light bulbs, optical LSR — in addition to plastics like polycarbonate and acrylic resins — is replacing glass in many optical applications including lens covers and light pipes.

Optical LSR is a transparent, flexible thermoset material that is replacing glass in many optical applications.

The flexible, transparent material is second in clarity only to glass; it can withstand heat in proximity to high-output LEDs and operate in a range of ambient temperatures. Optical LSR is flexible enough for rough duty, outdoor and automotive use. It also allows for very flexible design including accurate replication of fine features. It can support minor undercuts and negative draft without the need for side-actions, and both thick and thin walls. Designs in this material can often integrate multiple parts into a single unit, combining for example a lens, a clear lens cover and a sealing gasket, reducing the bill of materials for a final assembly.

Proto Labs stocks Dow Corning MS-1002 LSR, a material that has been engineered for molding finely detailed parts for LED applications. Read our full Design Tip to see how optical LSR might help on your next lighting project.