When Is a Colored Compound a Better Choice Than Masterbatch?

The order of gray housings for an electrical equipment manufacturer had been produced for years with the same material: a flame-retardant polypropylene that arrived from the supplier already colored. To lower costs, purchasing proposed replacing it with the same resin in natural plus a gray concentrate, and the shade matched on the first trial. The parts passed plant inspection and shipped on time. During the receiving audit, the customer's quality engineer requested the material certification sheet: the document covered the gray grade exactly as it came from the supplier, and the blend of natural resin with concentrate fell outside what that sheet covered. The customer held the shipment, requested flammability testing at the processor's expense, and its assembly line was left waiting. The savings per kilogram lasted until the first audit.

A colored compound is the right choice when the certification, properties, color tolerance or formulation of the part must be fixed from the material itself. For polyolefins in several colors, masterbatch usually offers better cost and flexibility.

The savings per kilogram that are lost in the customer's audit

A colored compound, also called precolored resin, is a material in which the pigment is already incorporated throughout the resin at the final concentration of the part; it is loaded into the hopper without dilution. Masterbatch carries the pigment at a high loading in a carrier resin and is dosed at a small percentage over natural resin. In our article on masterbatch, color concentrate and color pellets, we clarify that vocabulary and compare cost, inventory and color control. Here we address the next question: in which parts the compound is the right route, even though it costs more per kilogram.

Color fixed in the material or color adjustable at the machine

The two routes distribute responsibility differently. With a compound, the color, the additives and the properties are defined and measured at the compounder's plant, and the processor receives a closed material. With masterbatch, the final formula is completed at the processor's machine, with its feeder, its natural resin and its process. The first route provides documentary certainty in exchange for flexibility; the second provides flexibility and requires control at the plant.

Certifications tied to the material: the criterion that defines the route

Flammability, electrical safety and the customer specification

In electrical housings, appliance components and automotive parts, the part drawing usually specifies a particular material grade, and that grade frequently includes the color. Flammability or electrical performance certifications are issued for specific formulations, because a pigment or a carrier resin can modify how the material behaves when exposed to flame. Adding a concentrate at the plant creates a new combination, and that combination may require its own evaluation before it enters the customer's line.

When the specification names a colored, certified grade, the compound is the direct route, and switching to masterbatch becomes an engineering project with customer approval, testing and documentation.

Specifications that allow a concentrate

Some specifications allow natural resin with an approved concentrate at a defined let-down ratio. In those cases, masterbatch works under one condition: the carrier, the let-down ratio and the pigments must be documented and fixed. Depending on the application of the product, at Delta Pigmentos we work with FDA, ASTM, UL, CE and NOM references, and each concentrate is delivered with its technical proposal of product, concentration and recommended process. Before changing routes, we recommend asking the customer in writing what its specification allows.

Engineering plastics: when the carrier resin changes the properties

Property dilution caused by the carrier

Every masterbatch adds a fraction of carrier resin to the part. In polyolefins, with a carrier from the same family and typical let-down ratios, that contribution almost always goes unnoticed. In engineering plastics such as nylon, polycarbonate, ABS or PBT, a carrier made of a different polymer can reduce impact strength, alter the surface finish or cause delamination. The effect grows with the let-down ratio, and heavily pigmented shades are the most exposed.

The compound resolves that issue because it incorporates the pigment into the same resin as the part, with its reinforcements and additives, and the compounder is responsible for the properties of the finished material.

A concentrate tailored to the resin

The alternative, when the specification allows it, is a masterbatch formulated for that resin: a carrier of the same polymer or one compatible with it, pigments that withstand its processing temperature and a loading calculated for low dosing. That is how we develop concentrates for engineering plastics at Delta Pigmentos. Final validation comes from mechanical testing on the molded part.

Tight color tolerance and parts assembled side by side

Several machines, several plants, a single shade

A part that is molded on several machines, or at different plants, and later assembled next to components from another supplier multiplies the points where the color can vary. With masterbatch, each machine is a dosing point with its own feeder, its own calibration and its own shift. With a compound, the color arrives homogeneous throughout the material, and variation depends on a single point: the compounder's lot control.

A masterbatch with well-calibrated gravimetric feeders and a per-shift verification procedure can hold tight tolerances. When the plant does not yet have that control, or the customer approves the shade part against part in a visible assembly, the compound reduces that risk.

Processes with limited mixing capacity

Some machines provide little mixing: a short screw, very fast cycles, low back pressure or small shot sizes. There, a concentrate dosed at a very low percentage can leave streaks or areas of uneven shade. Before switching to a compound, it is advisable to review two adjustments: raising back pressure within what the part allows, and using a lower-loading concentrate dosed at a higher percentage, which is easier to distribute. If the part still shows streaks after both adjustments, the compound is the solution.

Complex formulations: color, reinforcement and additives in the same pellet

Some parts require color, glass fiber, flame retardant, stabilizers and impact modifiers all at once. A compounder incorporates everything in a single extrusion pass, with the dispersion and the content of each component measured in the finished material. Adding a color concentrate to a reinforced or flame-retardant grade introduces one more variable into a formula that already has little margin.

In these parts, shrinkage and warpage also matter. Some organic pigments act as nucleating agents in certain polymers and modify the shrinkage of the part; in a compound, that effect is validated once, with the complete formula.

Where masterbatch remains the most efficient route

A large share of polyolefin parts, such as blow molded containers, film, caps, pails and household goods, are colored with masterbatch for good reasons. A plant that works with several colors on the same natural resin keeps a short inventory, changes shade simply by changing bags and adjusts color intensity through the percentage. With a compound, each color is a separate material in the warehouse.

Masterbatch also facilitates low- and medium-volume developments. At Delta Pigmentos, a development color has a minimum order of 100 kg and, because of the dilution principle, that quantity colors a much larger volume of resin. For commonly used shades, we offer a Basic Color Line of 30 masterbatches for HDPE, LDPE and PP.

Five questions to decide the route before requesting a quote

We recommend answering these questions in writing, with purchasing, quality and engineering at the same table:

• Does the customer's drawing or specification name a colored material grade? If the answer is yes, the compound is the starting point.

• Does the part have a flammability, electrical or performance certification tied to the formulation? Any change of route requires the customer's approval.

• Is the resin an engineering plastic, and does the part depend on its impact or temperature resistance? The carrier of the concentrate must be validated with mechanical testing.

• Is the same shade molded on several machines or at several plants, or assembled next to parts from another supplier? The color tolerance calls for control at each dosing point, or else a compound.

• How many colors are produced on the same resin, and at what volume per color? Many colors at moderate volume favor masterbatch; a single high-volume color can justify the compound.

When the first four answers are negative, masterbatch is usually the route with the lowest cost per part and the greatest flexibility. When any of them is affirmative, the decision deserves a technical review before the purchase order is issued.

How we help you define the route at Delta Pigmentos

At Delta Pigmentos we have been manufacturing masterbatch in our own plant for 24 years, for polyolefins and engineering plastics, and we distribute organic and inorganic pigments. With the data for your part, our Quality Control, Design and Development laboratory evaluates whether a concentrate meets the requirement: carrier, loading, let-down ratio and processing temperature. When the specification requires a certified compound, we tell you so from the first review; for compounders, we supply the pigments, with color matching support.

The process is the same for any development. You send us your shade reference (Pantone code, physical sample or photograph), the polymer, the process and the end use, and we propose the product with its concentration, its recommended process, price and delivery time. You test the sample on your own machine and, once the shade is approved, we produce it under ISO 9001-2015 certified procedures and ship it anywhere in the country from Santa Anita, Jalisco. A development color takes 10 days from sample approval.

Frequently asked questions

Can a masterbatch match the color of the compound I use today?

Yes. The most direct way is to send us a current part as a physical reference, together with the polymer and the process. The laboratory formulates the concentrate against that part, and you validate it on your machine. If the part has a certification tied to the material, the change also requires the approval of your customer.

Does a colored compound guarantee more color uniformity than masterbatch?

It eliminates dosing at the plant, which is a frequent source of variation, and its uniformity depends on the lot control of its manufacturer. A masterbatch with a calibrated gravimetric feeder and per-shift verification can also hold tight tolerances.

What information do you need to evaluate whether my part can move from compound to masterbatch?

The polymer and its grade, the specification or certification that applies to the part, the process, the number of colors, the volume per color and the color tolerance your customer requires. With that information, we respond with a technical proposal or with the recommendation to keep the compound.

At Delta Pigmentos we have been manufacturing masterbatch in our own plant for 24 years, with our own laboratory and ISO 9001-2015 certified procedures, and we tell you clearly when your part calls for a different route. If you are about to decide between a colored compound and masterbatch for a part, write to us on WhatsApp from https://deltapigmentos.com with your polymer, your process, your specification and your volume per color; we will respond with a technical proposal. Every request is reviewed within the following 24 business hours.