Design Tip: Colorant and Color Matching

What Color is Your Prototype?

Injection molded parts, for all their many shapes and sizes, all start out pretty much the same—as small plastic pellets. The base colors of those pellets vary somewhat depending on the resin, but they all fall somewhere on a monochromatic scale from clear through various shades of natural to black (see Figure 1). Turning those dull little pellets into the rainbow of colors that comes out of molding presses requires the addition of colorant, which can be a fairly simple or fairly involved process. The complexity depends on how picky you are about your color.

Figure 1: Base color resins in their original pellet form. Left to right: acrylic (clear), ABS (natural), and glass-fiber nylon (natural).

If all you want, for example, is “red,” Protomold can add a stocked colorant to your base resin at no charge (see Figure 2). In fact, you can have your choice of Cherry Red, Flame Red, or Transparent Red, among others, though the exact color you end up with may depend somewhat on the shade of the base resin. If you want to see all the choices we offer, go to Protomold stocked colorants. Of course, how closely the final color resembles the color you see on your screen may depend on the screen itself, but it will certainly be red. If, on the other hand, you want a very specific color, say the blue of your corporate logo or the color-matched cap of a spray-paint can, the process becomes more complicated.

Figure 2: Adding Protomold stocked cherry red colorant to natural ABS created this plaque sample.

There are basically two ways to get colored injection molded parts. The simplest is to mix dye pellets into a batch of base resin pellets (see Figure 3). As the pellets are heated and compressed for injection into the mold, the base resin and dye pellets melt and mix together before being injected into the mold.

Figure 3: Typically colorant is mixed into base resin at 3% concentration to create colored parts. This photo shows a 3% colorant mix.

The other way is to order pre-compounded pellets in the exact color you want; for example, a standard PMS color or match to a sample swatch (see Figure 4).

Figure 4: Pre-compounded blue PC is supplied by a customer to Protomold for exact color parts.

There are several things you should keep in mind if you choose to have Protomold add the colorant.
1. As stated above, Protomold does not match specific colors.
2. The effect of base resin shade on final color is greater on light colors. In a pre-compounded color, this can be adjusted for in the compounding process, but may be noticeable when you use Protomold’s stock colors.
3. Because dye pellets are mixed with base resin pellets in a “salt and pepper” mix, there is a chance of "swirling” in the resulting parts (see Figure 5). The degree of swirling depends on a number of factors. “Hot” colorants—red, orange, yellow—tend to exhibit a higher swirling risk than cool colors like blue and green. Also, large parts, because they use more of the contents of the chamber in which resin pellets are melted and mixed, are less likely to show swirling than small parts.

Figure 5: Sample of swirling effect from a nylon material with yellow colorant. Choosing a pre-compounded resin would have helped the customer avoid this issue.

4. Unless you use pre-compounded colored resins, there is a risk of inconsistency from lot to lot and from part to part. This is one of the reasons that we recommend our standard ratio of three percent (3%) colorant (see Figure 6).

Figure 6: Colorant mixed with resin at 1, 2, and 3 percent ratios. With fewer dye pellets in the salt-and-pepper mix, the chance of uneven distribution goes up.

5. Certain base resins “don’t play well with others” when it comes to colorants. For these—high-temperature nylon and polycarbonate, for example—Protomold stocks a limited variety of resin-specific colorants. These allow you to achieve color but further limit your choice of hue.
6. Finally, certain resin characteristics—UV protection, flame retardant, and medical or food compatibility—can be affected by the choice of colorant. Protomold does not stock colorants specifically made to maintain these characteristics.

All of these problems have a solution: the use of pre-compounded resins purchased from specialized vendors. Pre-compounding consists of mixing colorant with base resin, melting and extruding the resin, re-pelletizing the resulting mix, and then repeating the process until a thorough mix is achieved. If necessary, the mix can be adjusted during the process to match the customer’s exact specifications. Vendors like RTP Plastics, PolyOne, Accek Color, Chase Plastic, and Compounding Solutions can match virtually any color in a wide variety of resins, and can preserve critical resin characteristics in the process (see full contact list below). Because the color is evenly distributed among the pellets, there are no issues of swirling or part-to-part inconsistency. Protomold can use these pre-compounded resins to produce parts, delivering all the benefits of rapid injection molding along with the exact color and characteristics you need.




What do the users really want!

what do the users really want?

what do the users really want?

jason raak | March 25, 2011 at 11:24 am |

catia to solidworks

A few weeks back I mentioned how I was confused as to why a CATIA translator in SolidWorks did not make the Top Ten list at SolidWorks WORLD this year. That one sentence began a firestorm of tweets about whether the translator was really a high priority among SolidWorks users.

First and foremost I need to mention that I live in West Michigan which is heavily entrenched in the auto industry. With that being said, almost everywhere I go and everyone I talk to in the Midwest have mentioned the NEED for the ability of SolidWorks to handle CATIA files natively. After all, both CAD programs are owned by parent company Dassault Systems.

One of the first comments made on Twitter stated the my feedback and the user base I usually talk to might be skewed compared to the entire SolidWorks user base and I totally agree with the comment. This may be the exact reason why it does not make it to the Top Ten list.

Still it leads to me think, what is the holdup of getting this translator incorporated into SolidWorks? There are many tools inside SolidWorks that are industry specific, things like Mold tools. So why should someone that has to constantly deal with CATIA files be forced to find workarounds in order to get their work done.

I personally know of a company that has a large number of SolidWorks licenses, however they also have a license of Autodesk Inventor for the sole reason of translating data. I am guessing that this is probably not how Dassault Systemes wants there customers working.

So what is the holdup? Is it pride? Is it the possibility of making more money by releasing an additional add in down the road that customers are going to have to buy? I don’t know the reasoning for it not being in the software already but I have to think that one of these is the deep rooted holdup. When or if it does come I sure hope that it does not come at an additional cost if you have the Professional or Premium SolidWorks packages.

This post is not meant to pick on Dassault Systemes, SolidWorks, a development team, or a specific development person but is more to ask the question of why are we still waiting. SolidWorks 2011 offers a wide range of translators for other popular CAD programs like Pro-E, Unigraphics, Inventor, Solid Edge, etc. but not CATIA yet.

Do you see the need? Why do you think we are still waiting?

Survey of Sustainability in the Plastics Industry

Subject: Survey of Sustainability in the Plastics Industry


SPE members will soon have access to updated comprehensive information on “Sustainability in the Plastics Industry.”

A graduate student at Missouri University of Science and Technology is conducting a survey to measure how plastics industry companies have incorporated sustainability into their agendas and activities. The survey is open through April 13, 2011 and as an SPE Member you are invited to participate.

Do you want to know how your company compares with others in terms of sustainability? How do other companies benchmark sustainability? What has been the impact of the economic downturn on sustainability? As an SPE Member, you can find the answers to these questions just by participating. The survey allows you to remain anonymous. Your individual information is confidential, and only the compiled findings will be published.
The results of this survey will be shared with the membership of SPE during ANTEC 2011- May 1 to 5, in Boston, MA. Additionally, SPE members will have full access online to the survey results when completed.

To participate in the Sustainability in the Plastics Industry Survey, please go to:


Susan Oderwald
Executive Director

3D Printing News – Feb 23 2011

3D Printer Will Print Body Parts Within the Next 20 Years
By James Mulroy, PCWorld Feb 22, 2011 10:08 AM A MakerBot 3D printer.What if you could do anything you wanted without worrying about losing some limbs? That day may be here soon! Researchers in the Computational Synthesis Laboratory at Cornell
See all stories on this topic »
3D Systems Delivers Plus Upgrades for Its ProJet(TM) 3D Printers (press release)
23, 2011 (GLOBE NEWSWIRE) — 3D Systems (Nasdaq:TDSC) announced today the immediate availability of new Plus upgrades for its ProJet™ HD 3000 and CPX 3000 3D printers. These productivity upgrades provide measurable value for current customers,
See all stories on this topic »
Make your own guitar with a 3D printer
Reg Hardware
By Caleb Cox • Get more from this author This is the Zoybar Tor, created by a musician called Bård SD, using the open-source 3D modelling software Blender. Bård then had the body parts printed by Shapeways on a 3D printer for $175.
See all stories on this topic »
Supply Chain News: How Soon will "Printed" Parts Revolutionize Supply Chains
Supply Chain Digest
Digital printing industry analyst Terry Wohlers, for example, says right now more than 20% of the output of 3D printers is for final products, not just prototypes, and he predicts that this will rise to 50% by 2020. And that would be with significant
See all stories on this topic »
Recognizing Creativity and Innovation in 3D Printing | Public
By Michael Weinberg
The world of 3D printing was in a tizzy last week discussing a DMCA takedown notice received by the website Thingiverse, a website that allows users to share and discuss their 3D printed designs. It was something of a milestone because
Tag: Intellectual Property –
3D printing gets its first DMCA notice | American Libraries Magazine
By Griffey
American Libraries Magazine, the magazine of the American Library Association, delivers news and information about the library community.
American Libraries Magazine -… –
3D-Printed Skin Could Revolutionize Treatment for Burn Victims
By Timon Singh
Scientists Use 3D Printer to Create First “Printed” Human Vein. 3D Printing technology has recently leapt into a new realm — we’ve seen printers that can create entire buildings out of stone, delicious meals out
3D Printing: The most important innovation you’ve never heard of
3D printing is also already being developed worldwide, and the Global North Because 3D printing makes it easier to manufacture and copy individual…

Rapid Prototyping NEWS – Feb 23 2011

3D Systems buys Quickparts
Plastics News
22, 12:15 pm ET) — 3D Systems Corp. has acquired rapid prototyping specialist Quickparts Inc. Rock Hill-based 3D Systems launched 3Dproparts, a rapid prototyping and manufacturing parts service, in October 2009. Since then, it has expanded
See all stories on this topic »
Trine to honor engineers
Coldwater Daily Reporter
Civil engineers will give a hydraulic flume demonstration; the department of technology will give demonstrations in rapid prototyping; advanced manufacturing will have demonstrations; mechanical engineers will give a foundry demonstration;
See all stories on this topic »
Next step for Unreal Engine 3 revealed at GDC | Game Development
Epic added that will host a free advanced training session for Unreal Engine 3 licensees; with guidance offered on content creation best practices to rapid prototyping with Unreal Kismet. Those interested should email Mark Rein.
Develop –
Rapid Prototyping With Sinatra | Design Shack
Reading an article entitled Rapid Prototyping With Sinatra on Design Shack.
Where to buy Rapid prototype machines? – Yahoo! Answers
I would like to know the best Brand of Rapid proto……

Power for Electronic ‘Super Skin’

Power for Electronic ‘Super Skin’

By Louis Bergeron, Stanford University

Thursday, March 10, 2011

The foundation for the artificial skin is a flexible organic transistor, made with flexible polymers and carbon-based materials.

"Super skin" is what Stanford researcher Zhenan Bao wants to create. She’s already developed a flexible sensor that is so sensitive to pressure it can feel a fly touch down. Now she’s working to add the ability to detect chemicals and sense various kinds of biological molecules. She’s also making the skin self-powering, using polymer solar cells to generate electricity. And the new solar cells are not just flexible, but stretchable – they can be stretched up to 30 percent beyond their original length and snap back without any damage or loss of power.

Super skin, indeed.

"With artificial skin, we can basically incorporate any function we desire," said Bao, a professor of chemical engineering. "That is why I call our skin ‘super skin.’ It is much more than what we think of as normal skin."

The foundation for the artificial skin is a flexible organic transistor, made with flexible polymers and carbon-based materials. To allow touch sensing, the transistor contains a thin, highly elastic rubber layer, molded into a grid of tiny inverted pyramids. When pressed, this layer changes thickness, which changes the current flow through the transistor. The sensors have from several hundred thousand to 25 million pyramids per square centimeter, corresponding to the desired level of sensitivity.

To sense a particular biological molecule, the surface of the transistor has to be coated with another molecule to which the first one will bind when it comes into contact. The coating layer only needs to be a nanometer or two thick.

"Depending on what kind of material we put on the sensors and how we modify the semiconducting material in the transistor, we can adjust the sensors to sense chemicals or biological material," she said.

Bao’s team has successfully demonstrated the concept by detecting a certain kind of DNA. The researchers are now working on extending the technique to detect proteins, which could prove useful for medical diagnostics purposes.

"For any particular disease, there are usually one or more specific proteins associated with it – called biomarkers – that are akin to a ‘smoking gun,’ and detecting those protein biomarkers will allow us to diagnose the disease," Bao said.

The same approach would allow the sensors to detect chemicals, she said. By adjusting aspects of the transistor structure, the super skin can detect chemical substances in either vapor or liquid environments.

Regardless of what the sensors are detecting, they have to transmit electronic signals to get their data to the processing center, whether it is a human brain or a computer.

Having the sensors run on the sun’s energy makes generating the needed power simpler than using batteries or hooking up to the electrical grid, allowing the sensors to be lighter and more mobile. And having solar cells that are stretchable opens up other applications.

A recent research paper by Bao, describing the stretchable solar cells, will appear in an upcoming issue of Advanced Materials. The paper details the ability of the cells to be stretched in one direction, but she said her group has since demonstrated that the cells can be designed to stretch along two axes.

The cells have a wavy microstructure that extends like an accordion when stretched. A liquid metal electrode conforms to the wavy surface of the device in both its relaxed and stretched states.

"One of the applications where stretchable solar cells would be useful is in fabrics for uniforms and other clothes," said Darren Lipomi, a postdoctoral fellow in Bao’s lab and lead author of the paper.

"There are parts of the body, at the elbow for example, where movement stretches the skin and clothes," he said. "A device that was only flexible, not stretchable, would crack if bonded to parts of machines or of the body that extend when moved." Stretchability would be useful in bonding solar cells to curved surfaces without cracking or wrinkling, such as the exteriors of cars, lenses and architectural elements.

The solar cells continue to generate electricity while they are stretched out, producing a continuous flow of electricity for data transmission from the sensors.

Bao said she sees the super skin as much more than a super mimic of human skin; it could allow robots or other devices to perform functions beyond what human skin can do.

"You can imagine a robot hand that can be used to touch some liquid and detect certain markers or a certain protein that is associated with some kind of disease and the robot will be able to effectively say, ‘Oh, this person has that disease,’" she said. "Or the robot might touch the sweat from somebody and be able to say, ‘Oh, this person is drunk.’"

Finally, Bao has figured out how to replace the materials used in earlier versions of the transistor with biodegradable materials. Now, not only will the super skin be more versatile and powerful, it will also be more eco-friendly.

3D printing for architects

3D printing for architects

Initially, 3D printing was not created for architects. In fact, most 3D printer manufacturers probably didn’t even foresee their machines’ potential in architecture.

The printers were mainly designed for the aerospace and automotive industries, or other sectors requiring physical realization of elements in order to test their design.

Things have changed, and 3D CAD applications are now very much a part of the design process. 3D printing has become a strategic necessity for architects.

The question is no longer “should we go into this?” but rather “how are we going to integrate 3D printing into our business?”

Architects can use 3D printed models in the same way as hand-made ones. But they have the added benefit of being faster to design, less costly and more accurate.

Many architects recognize the ease of use of 3D modeling software such as Google SketchUp, which is particularly useful in the early stages of design, when multiple iterations of a model are required.

The problem is that SketchUp, like many other 3D CAD applications, is more of a rendering tool than a solid modeling system. Designers must therefore be especially careful when preparing their model for 3D printing to ensure a flawless print. To be honest, it should be noted that Google’s v8 of SketchUp has resulted in marked improvements in addressing the needs of solid modeling.

Below is an example that illustrates how 3D printing has become essential for any architecture firm.

On its blog, 3D printer manufacturer Zcorporation quotes from a recent article in Building Design.

We learn that British Education Secretary Michael Gove called Amanda Levet “Britain’s best architect” at the Globe Academy’s opening ceremony.

Said Gove: “So much care and attention and the work of Britain’s best architect has gone into providing you with the best possible building in which to spend the next few years.” He said everyone involved in the design had “shaped a building which is impressive on the outside and beautiful on the inside”.