Clear 3D Printing UK | Transparent SLA Parts

Complete Fabrication makes clear and transparent 3D printed parts using SLA (stereolithography) in two clear resins, Somos WaterClear Ultra 10122 and MPC12 Clear. Parts come off the machine translucent, so we finish them by polishing or clear-coating to a water-clear finish. Clear parts are used for light pipes, fluidics, see-through housings, lenses and display models. We have made prototypes in Whittlesford, near Cambridge, since 1986.

Which clear resin to choose

	Somos WaterClear Ultra 10122	MPC12 Clear
Best for	Light pipes, lenses, bottles and light transmission tests	Clear functional parts, flow visualisation, photo-elastic testing and casting patterns
Appearance	Optically clear, acrylic-like, refractive index 1.52	Clear, multipurpose
Tensile strength	56 MPa	50 to 56 MPa
Elongation at break	7.5%	8 to 15%
Heat deflection temperature	47 °C (0.46 MPa)	49 °C (0.45 MPa)
Data sheet	Somos WaterClear Ultra 10122	MPC12 Clear

Figures are typical values from the manufacturers' data sheets, and are not a guarantee for a finished part.

Why clear 3D prints look frosted, and how we fix it

SLA builds each part in thin layers, and the tiny steps between layers scatter light, so a clear print looks frosted straight off the machine. We remove those steps by polishing or clear-coating the surface, which gives a true water-clear finish. Polishing works best on faces we can reach, and clear-coating suits more complex shapes.

We can achieve good clarity with post-processing on any thickness, but thinner is better for a natural finish clarity. (Chris, 3D Print Department Manager)

What clear 3D printed parts are used for

Light pipes and light guides. WaterClear's refractive index of 1.52 suits light transmission tests.
Fluidics and flow visualisation. Clear manifolds let you see flow, bubbles and leaks.
See-through housings. Show internal mechanisms on display models or for assembly checks.
Lenses and covers. Concept and functional models before tooling.
Photo-elastic testing. MPC12 Clear is listed for this use.
Exhibition models. We grew clear, sectioned hearts to show each valve position for a maker of replacement heart valves.

Designing a part to be clear

Mark the optical faces. Tell us which faces must be see-through, so we can plan the build and finishing around them.
Favour open, reachable faces. Flat and gently curved faces polish best. Deep, narrow recesses are hard to reach.
Split clear and opaque parts. If only a window must be clear, make it a separate part. The housing can then be printed in a tougher resin and painted.
Say how clear is clear enough. A see-through cover for a display model needs less finishing than a lens for a light test.

The limits of clear SLA

Yellowing. Clear photopolymers can yellow over time, especially in sunlight. For parts that must stay clear for years, we compare clear vacuum casting.
Internal channels. We can only polish faces we can reach, so internal channels stay as printed and look less clear.
Heat. The data sheets give a heat deflection temperature of 47 °C for WaterClear and 49 °C for MPC12, so keep clear parts away from hot environments and hot fluids.

Other ways to make clear parts

For several identical clear parts, vacuum casting in clear polyurethane copies an SLA master, so parts come from one silicone mould instead of being finished one by one. We used this route for the I-Dration water bottle: we grew the bottle in two parts on our SLA machine, vacuum cast it in clear polyurethane and bonded the top and bottom for a watertight seal. For acrylic parts we use CNC machining, as we did for the full-size figures that hold our heart valve models. FDM 3D printing in PETG can give translucent parts, but SLA gives the clearer result.

Turnaround and what we need to quote

CAD received by 5:30 pm is usually delivered the next day when capacity allows. Polishing to water-clear adds finishing time, which we confirm at quote. To quote your clear parts we need:

CAD files, ideally STEP
The quantity, or the range you are considering
Which faces must be clear, and how the part will be lit or used
How clear is clear enough for the job
When you need the parts

There is no minimum order. Send your brief to Info@compfab.co.uk, call +44 1223 836837, or use the contact page.

Frequently asked questions

Can 3D printing be clear?

Yes. SLA 3D printing in a clear resin makes translucent parts, and polishing or clear-coating makes them water-clear.

What is the clearest 3D printing material?

Somos WaterClear Ultra 10122, an optically clear SLA resin with an acrylic-like appearance and a refractive index of 1.52.

Do clear 3D printed parts turn yellow?

Over time they can, especially in sunlight. For parts that must stay clear for years, we compare clear vacuum casting.

Can the inside of a clear 3D printed part be made clear?

Only partly. We can polish faces we can reach, but internal channels stay as printed and look less clear.

How thick can a clear 3D printed part be?

Any thickness can be made clear with post-processing, but thinner walls give a more natural clear finish.

When is vacuum casting better for clear parts?

Usually when you need several identical clear parts, because the parts are cast from one silicone mould instead of being finished one by one.