The Challenge of Color Consistency
The Importance of Production Volume
Standard Color Systems
The great value of color chip samples is that they have standard reference numbers. This takes the guesswork out of the mixing process. Although there are many thousands of standard reference colors, be aware there are millions of possible shades and hues. That’s why many systems and color reference charts are also used.
Masterbatch is a highly concentrated pigment used to make large volumes of colored injection molding resin.
Plastic masterbatch pigment is mixed at a ratio of one part of color masterbatch to 24 parts of base material. This means that a little masterbatch goes a long way. And, since it’s sold in minimum order quantities of two metric tons, this represents a very large number of finished parts.
Achieving Consistency For Low Volumes
There are three standard methods for preparing relatively low volumes of color molded parts.
Standard Pantone or RAL colors are consistent among all suppliers. If you give us a Pantone number, or a similar color matching system, we can make sure you get exactly the color you want.
Customer supplied material
If you’re able to provide your own resin, you will get the color you want. But we must have enough material to fulfill the order.
Material compounder may have leftover stock. This can be a good way to purchase resin without needing to make a large MOQ order.
100% Color Matching in an Assembly
A family mold is a multi-cavity tool that makes all of the parts of an assembly in one cycle. The benefit of a family mold is that the parts are guaranteed to be the same color, but they take longer to make and are more costly.
Another option to consider is painting your parts after they’ve been molded. Of course you will want to use a paint color that is very close to the base material. This option adds another step so it takes longer and is more expensive.
Custom Colors For Different Volumes
- Use pigments in the hopper (low-volume)
- Purchase custom compound material (high-volume)
- Use a masterbatch colorant (very high-volume)
Pigments Mixed in the Hopper
In this method, uncolored plastic pellets are mixed with colored pigment in the machine hopper before the resin is injected. Product developers should know that there are still some compromises when using this method.
When pigmented powder is mixed in the barrel, the distribution is not 100% predictable or uniform since some areas will stick more than others.
Pigmented powder is naturally very thin. For this reason, it can sometimes burn when it’s heated, and this will show up as black spots on the finished parts.
Special care must be taken to ensure that atmospheric moisture does not contaminate the resin mix when pigment is added.
Custom Colors for High Volumes
The best way to produce high volumes of color molded parts is by using pre-mixed compounds or masterbatch, both of which have trade-offs to consider.
Masterbatch pigment is highly pigmented, with a 24:1 ratio of uncolored pellets to masterbatch. This yields consistent colors but it represents 50 tons of finished parts, so clearly this approach is suitable only for the highest volumes.
Resin formulators can offer custom colors directly from their factory, but they have MOQs of one ton of resin. This represents a large volume of parts, but these can be spread out over many separate production runs.