Printing Optically Clear: The Misconception

November 18th, 2013

By: Ben Folwell

A common material misconception in additive manufacturing is the ability to print optically clear parts directly off the printer. While this is possible in some cases, it is largely dependent on the part geometry and printer settings. In most cases parts cannot reach clarity without some good old fashioned elbow grease. To begin, I think it is important to determine the difference between an object that is translucent vs. an object that is transparent.

Translucency is when a surface allows light, but not detailed images, to pass through; semitransparent.
Transparency is when a surface allows light to pass through so that objects behind can be distinctly seen.

So what exactly are the steps needed to take in order to achieve a perfectly transparent part?

For the purpose of this example we are using Stratasys™VeroClear material that can be used on their Objet equipment which we have aptly named VeroTranslucent. After VeroTranslucent parts are removed from the printer they are typically completely covered in support material. After the support material is removed the parts have layer lines visible along the surface of the parts causing a cloudy tint.

This leads us to the elbow grease part…

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The process to transparency began with a coarse sandpaper of 150 grit. To continually smooth the part surface the process requires gradually increasing to finer grades of sandpaper ultimately ending with 2,000 grit sandpaper. The layer lines are now gone, but my part is only translucent; I want transparent.

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The final step of the process was buffing the part with a rubbing compound to remove any scratches that were left from the 2,000 grit sandpaper and hit it with a machine polish. The machine polish buffing gives the part a shine and glass-like look to it.

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WAH-LAH! After a few hours of post-finishing work and a little bit o’ elbow grease, my part is optically clear and you can visibly see the VeroWhite skull that was printed inside. After creating a design like this, it really makes you dream about the world of possibilities with 3D printing.

You dream it. We GROWit.

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