Assigning transparency for PolyJet in GrabCAD Print

GrabCAD Print for PolyJet offers a number of settings to achieve transparency. Several factors determine which options to use, and which options are enabled. Depending on the specific needs and circumstances, you can utilize the transparency slider, the Alpha input channel, the Translucent checkbox, various digital materials (DMs), or direct VeroClear assignment.
This tutorial will explain what each transparency setting in GrabCAD Print does and how each works, so users can understand their options and the differences between them.

  1. Step 1: What Are the GrabCAD Print Settings that Offer Transparency?

    The GrabCAD Print settings menu offers these options for assigning transparency and printing transparent parts:

    1)     The Alpha channel and transparency slider

    2)     The Translucent checkbox

    3)     Transparent PolyJet materials

    a) Single-material assignment

    b) Digital Material (DM) or CMYK input assignment (multi-material combinations)

    Which options you can and should use depends on which materials you have loaded into the printer.

    This table and workflow apply to model files that have been imported without color or texture assignments:

    Note that there are 3 additional features that are enabled when using VeroVivid rather than Vero CMY.

    1)     The option of using the Translucent checkbox.

    2)     The option of using the Translucent checkbox together with the Digital Materials menu.

    3)     The option to achieve transparency without adding VeroClear.

    So, which materials do you choose? What is the difference? It depends on your requirements, materials available, and other factors. Each material and option selected will affect appearance differently. 

  2. Step 2: When and How to Use the Alpha/Transparency Slider and Input Channel

    The color picker and transparency selection tools, compatible with Veros and VeroVivids, offer more control and a wider array of options. However, this method may also need more trial and error if a specific color and transparency is required. You cannot select a color DM and then use these options to further adjust transparency with the Alpha Channel and Transparency Slider.

    One way of explaining the color and transparency selection tools is that they offer a wider range of color and transparency combinations. It is ideal for people who need more control over color and transparency. 

    To use this setting:

    a)      Make sure that you have at least CMY colors and VeroClear loaded in the cabinet.

    b)     From the color picker, select a color.

    c)      Adjust the Alpha value using either the slider or the channel input. This will add or subtract VeroClear from your selection.

     When selecting an Alpha value:

    ·      1 = no VeroClear is used

    ·      0 = only VeroClear (i.e. no color) is used

    The color/transparency assignments will be uniformly applied to the entire part by default. 

    Pro Tips:

    1.      If you are experimenting with a new color and/or transparency value, you can try printing a sample geometry with the color assigned to review the outcome before committing to large prints.

    2.      At present, the onscreen simulation does not accurately represent the printed outcome in some cases. Future release versions will improve this preview. 

  3. Step 3: When and How to Use the Translucent Checkbox

    The Translucent checkbox is compatible with VeroVivid materials and all VeroVivid DMs, even those that incorporate regular Vero materials.

    The VeroVivid colors are used to achieve the widest color gamut and best color reproduction and we highly using recommend them. VeroVivid materials are transparent, but since most color applications require opaque colors, GrabCAD Print by default prints these colors onto a white core, resulting in an opaque part. 

    This displays VeroVivid’s fantastic color to its best advantage, but negates the transparency.

    For transparent parts with VeroVivid materials, you must perform the following steps:

    1.      Ensure the following materials are loaded:

    ·      All Vivid materials

    ·      VeroClear

    ·      VeroPureWhite

    ·      VeroBlackPlus

    2.      Select your desired color / DM / single material

    3.      Enable the Translucent checkbox. The Translucent checkbox can be found below the color picker.

    Selecting the Translucent checkbox disables the white core and assigns VeroVivid throughout the entire part.

    If the Translucent checkbox is unselected, and a Vero Vivid DM has been assigned, the part will be printed opaque.

    It can also cause a noticeable “frame effect” in certain geometries, as shown below. 

    The depth of color is affected by the thickness of the part, as shown in the picture below. Both models are printed in VeroVivid Yellow with no white core. The only difference between them is their wall thickness.

  4. Step 4: When to Use Vero and VeroVivid DM Material Assignment to Achieve Transparency

    Transparency is achievable with many DM material combinations. And it is an easy way to achieve a wide range of beautiful, pre-defined results.

    DMs offer predictable, pre-selected ranges of color combined with transparency. You can save time and money by printing out the Vivid DM triangles as an easy selection tool.

    These Vivid triangles are available on GrabCAD community library and through GrabCAD Print directly.

    Using the DMs makes the color selection process more predictable and easier to understand, enabling better alignment of color expectations on an individual and organizational level.

    The trade-off to using pre-defined transparent DM mixes, both with Vero and with VeroVivid, is that it disables the Transparency Slider. This results in fewer color options, which means less flexibility to adjust color and levels of transparency. The incremental jumps between color can be bigger than you desire. One can describe this option as more automated and beginner-friendly, ideal for people who want to achieve beautiful results without investing too much time and material into experimentation.

    A note about assigning transparency via a DM of Vero and VeroClear

    It is important to note that, although this combination will achieve transparency, it will be more translucent and pastel in appearance due to the presence of white material in the regular (non-vivid) Vero materials. 

  5. Step 5: When to Use CMYK input to Achieve Transparency

    The newest GrabCAD Print release 1.38 and above features an option to input CMYK values als well as RGB. Assigning colors via CMYK input directly is another way to create Digital Material mixes. This is a very powerful tool that offers the ultimate flexibility and control in color and transparency assignments. Typically, this tool would be used when iterating critical colors, such as those used in company branding. 

    The CMYK input tool is the most advanced material assignment method, as each material channel can be assigned individually. 

    Because of its complexity, it is recommended to iterate on sample geometry to obtain the required colors. Once you identify the CMYKWT (Transparent) color / material combination, you can save it to favorites for future ease of use. 

    This tool is different than RGB input, as this directly affects the color printed without remapping through a profile. This tool will be explored fully in another tutorial.

    Here is a quick video that shows how to understand and assign transparency within GrabCAD Print:

    And that is the GrabCAD Print workflow for assigning transparency. We will soon be publishing another tutorial offering alternative, often more advanced methods for assigning transparency.

    This concludes our tutorial about transparency, inspired by real customers’ questions and requests. Would you like us to write a tutorial about a different topic? Just let us know by leaving a comment below.