Sherlock, transparent tile, Formlabs


How to Create Transparent 3D Printed Parts with Clear Resin

The Formlabs Clear Resin is great for producing parts needing translucency, and with the right post-processing techniques, transparency.

Use the following finishing methods to create transparent 3D printed parts for a variety of applications, from optics to light pipes to fluidics. Methods range from quick solutions for adequate transparency, to niche techniques for creating optically clear parts.

The Formlabs Clear Resin is perfect for showing housing LEDs, inner details, or creating windows. Formlabs and their customers have used Clear Resin to produce a completely optically clear lens for a fully 3D printed camera, tiles for a Fresnel lens installation in Times Square, millifluidic devices and more.

3D Printed Lens for a fully 3D Printed Camera

Formlabs applications engineer Amos Dudley designed and 3D printed a lens for a fully 3D printed camera.


Techniques for Post-Processing Clear 3D Prints

Formlabs have tested several techniques for post-processing parts printed in Clear Resin. Cover manual sanding, clear coating and resin dipping will be covered in this post. Each finishing option requires varying levels of effort, depending on the degree of transparency and surface finish your part needs.


Manual Sanding and Polishing

Applications: For simple shapes with few details, manual sanding and polishing can be effective. However, they are less suited to finishing complex models. It is extremely difficult to reach total optical transparency with this technique.

You’ll have to sand to extremely fine grits to manually finish a transparent part, but with some effort, sanding and polishing parts to be as clear as a magnifying glass is possible. However, it is very challenging to completely eliminate all layer lines via manual finishing – micro scratches may be noticeable when holding the part at a shallow angle to the light.   

Instructions: To smooth you surface - use a range of incremental sandpaper grits then polish the part with acrylic cleaner and a microfiber cloth.

At around 3000 grit, stereolithography (SLA) printed parts become glossy and very smooth to the touch and by 12000 grit, they achieve reflectiveness. Try using a range of sandpaper and micromesh pads with grits from 400 to 12000, in increments of 200, slowly and carefully clean the lens between grit levels and eliminate scratches from the previous level before moving on to the next.

Formlabs support site offers a simple visual step-by-step guide for manual sanding, including an optional finish with acrylic spray.

Note: If semi-transparency is only needed, mineral oil can be used to create an even finish and hide any light spots on your part.

3D Printed Camera Lenses

Formlabs have tested a variety of methods of polishing clear 3D prints, from hand sanding and spray coating to resin dipping.


Formlabs 3D Printer


Spray Coating

Applications: Spray coating is a simple and a fast way to improve the clarity of parts without much reduction in detail. This technique is effective for all kinds of models, as it’s able to coat intricate details that may be hard to reach with normal sanding and polishing.

Clear coating itself helps to disguise layer lines and acts as UV protection. UV exposure can cause yellowing and unintended post-curing. If you’re looking for a smooth, glass-like surface finish, perform the manual sanding and polishing technique before coating. The more sanding done before the clear coating, the clarity improves. This extra step is great for post-processing prototypes that look like fully transparent plastic, for example; packaging, bottles and microfluidics.

Instructions: There are numerous options for clear coating, from low-cost sprays to products that require a dedicated room and tools.

  • General purpose clear coat spray paints: Options range from decent to low-cost options such as Rustoleum Painter’s Touch 2X to affordable but higher quality sprays such as Spray Max 2k Clear Glamor.
  • Automotive sprays: Products similar to Lesonal Universal Clear, a high-solids acrylic urethane clear coat, offer very high gloss and are designed for air-dry baking conditions, but need a spray gun and space for spraying. Lesonal Universal Clear and similar sprays require a base coat.

For spray coating, start with a clean, dry part already washed in isopropyl alcohol (IPA). Do not post-cure the part ahead of spraying, as this can cause yellowing. Let the part air dry. Once it’s completely dry, apply two to three spray coats in a dust-free environment.

Note: For a fee, auto body shops may do the coating for you with a spray like Lesonal Universal Clear. In most cases, these shops will use a light solvent, like naptha to clean and prepare the part’s surface prior to painting.

Times Square 3D Printed Tiles, Window to the Heart

For an installation in Times Square, Window to the Heart, the Formlabs and Aranda/Lasch teams worked with an auto body shop to spray coat each tile in Lesonal Universal Clear.


Resin Coating

Applications: This method is best for when you need very transparent parts, and only works on flat or near-flat surfaces, such as a lens or a window into the interior of a part.

Resin dipping results in parts that are extremely smooth, with clear and sharp surface reflections.

Note: This technique can be used to create an even smoother finish for parts printed in other SLA materials, although it can reduce detail.

Instructions: Apply Clear Resin to the part with drops from a syringe, or by dipping the part as desired. The viscous resin will fill layers and scratches on the part, forming a completely smooth surface.

The layer of resin should be as thin as possible, while still eliminating layer lines. Pull off any bubbles with a syringe. Completely post-cure the part using the appropriate settings and then repeat the process for the other side, both dipping and post-curing.

3D Printed Camera Final Lenses

Three stages of resin-dipped lenses, with the final lens on the left


Note: The dipping process alters focal length slightly for lenses. For the Formlabs 3D printed camera lens, Formlabs applications engineer Amos Dudley designed and printed a lens testing device.


Formlabs 3D Printer


For more information on Formlabs or 3D printingcontact us today on 1300 667 263.

Autodesk® AutoCAD® software
Ultimaker 3 3D Printer
Featuring seamless hardware, software and material integration the Ultimaker 3 3D printer creates complex geometries and achieves remarkable design intricacy with the most reliable dual extrusion on the market.
Autodesk Revit
Autodesk Revit software is built for Building Information Modelling (BIM), helping professionals design, build, and maintain higher-quality buildings.
Autodesk Architecture, Engineering and Construction Collection
This collection equips you to design higher quality and more sustainable buildings. Build your capability to deliver great design.
Autodesk Product Design & Manufacturing Collection
The Autodesk Product Design and Manufacturing Collection is the best way to access the most essential Autodesk software for product and factory design.
Autodesk Media and Entertainment Collection
Digital content creation tools for efficient 3D animation, compelling effects, believable 3D characters, and stunning environments for film, TV and game workflows.
Design every detail with AutoCAD software. Share your work with confidence using Trusted DWG™ technology, and connect your workflow across integrated desktop, cloud, and mobile solutions.
Autodesk Inventor
Autodesk Inventor—professional grade design and engineering tools that help you make great products.
Contact us 1300 667 263
Redstack Facebook Redstack Twitter Redstack Youtube Redstack LinkedIn Redstack Google Plus Redstack Intagram
Contact us 1300 667 263
Scroll to the top