The color of your plastic part can be an important aspect of its perceived quality. In this industry, many of the materials (or resins) that are used are off-white, translucent, or yellow and those bland colors can have a negative impact on the appearance of your end product and your customers' opinion of the piece. Consequently, you should give serious consideration to the color of your parts.
The process of adding custom color to your part can range from a rather simple process to something that can be incredibly complicated. It all depends on how particular you are about the specificity and consistency of the color. Here’s a quick explanation of the two most popular coloring methods that will help you determine which one would make the most sense for your future projects.
- Mixing Colorant With the Natural Material. This is usually the simplest and most cost-effective method when conducting low-volume production. Dye pellets are added simultaneously with the natural pellets into the injection molding machine. The pellets are then heated in preparation for the molding and mixed together creating the colored resin. The higher the ratio of dye pellets, the deeper and richer the color. Disadvantages of this method include swirling (an incomplete mixture of color), loss of resin characteristics (flame retardancy or food compatibility for example), and possible appearance of the base resin shade.
- Purchasing Custom Compounded Plastic. These custom-colored plastic pellets can be purchased from a number of specialized vendors. However, there is a minimum of one ton that must be purchased on the open market, making this a suitable option for only large scale productions. This process consists of the vendor mixing the colorant with the base material, melting and extruding the resin and then re-pelletizing this mixture. Although this option requires large-scale production and is a bit pricer, it provides the most color consistency and keeps resin characteristics intact.
While these are not the only two methods that can be used to add color to your parts, they are the most reliable and environmentally friendly. Unlike painting or plating, the processes above use the color as a component that is woven into your part, not just applied to the surface. There is no risk of scratching or peeling revealing an underlying color and the overall quality is much higher.
We hope this information is helpful as you consider your next color-specific small parts plastic injection molding project! If you have questions or would like a list of recommended vendors, we would love to hear from you.