What is transparency

Prototype of a trasparent model

Guide on the production of transparent models (1 of 3)

This guide is intended to help you understand how transparent models can be obtained from 3D printing and vacuum casting and, starting from the definition of the concept of transparency, provides indications on the possibilities and limits of these two solutions.

The guide is divided into three articles that deal with the following topics:

In the support area of the site is also available the guide on transparent models in complete and printable format.

What is transparency?

When we say "transparent" we are all pretty sure of what we mean, but there are aspects of the concept of transparency that are worth investigating, to better understand what you can expect when you want to get a transparent prototype from 3D printing.
Transparency is the capability of a body to allow the passage of light and therefore the vision of objects located beyond it.
This capability is determined by two factors:

  1. by the material of which the object is made, i.e. by its index of refraction: for example, having conventionally set the index of refraction of the vacuum to 1, the air is indexed 1.00029, the water 1.33, the glass about 1.5, the diamond 2.4;
  2. by the surface of the object: if the surface is rough, the actual incidence angle of light is not what you see macroscopically but varies from point to point because the various light rays hit the microscopic facets of the roughness, each characterized by a normal, with an overall effect of reflection and diffusion or alteration of the path of the light rays, which reduces the actual transparency.
Tabella degli indici di rifrazione di alcuni materiali

As a consequence, to obtain a transparent prototype it is necessary:

  1. to use a material with a good index of refraction, i.e. what we would call a transparent material;
  2. to have a surface as shiny as possible and free of macroscopic or microscopic geometric discontinuities.

In the next article we will talk about how to get transparent models.