Plastic coloring is a routine process in manufacturing. Many factories choose solid masterbatch because it is familiar and widely available. However, solid masterbatch comes with certain limitations that affect production efficiency, product quality, and the working environment.

Liquid color offers an alternative approach. It disperses pigments in a liquid carrier and is injected directly into processing equipment via a metering pump. This technology is used extensively in global markets.

Understanding the practical differences between the two solutions helps manufacturers make informed decisions based on their specific production needs.

Differences in Color Changeover Time

Solid masterbatch requires a lengthy changeover process. Because it exists in pellet form, it must pass through the solid conveying zone, melting zone, and metering zone of the screw to deliver color. When switching colors, the masterbatch remaining in the screw and barrel must be purged repeatedly. For dark-to-light or black-to-white changes, purge times typically range from 20 to 40 minutes, consuming significant amounts of material.

Liquid color is injected directly into the melt stream via a metering pump, bypassing the solid conveying zone of the screw. During a color change, only the injection point needs to be switched, leaving minimal residue. In practice, changeover time with liquid color can be reduced to under five minutes.

Shortening changeover time directly increases productive machine time. For factories that change colors frequently, this difference is especially significant.

Differences in Color Consistency

Solid masterbatch relies on screw shear force to break down pigment agglomerates. This process is influenced by equipment parameters, screw wear, and residence time. When production conditions fluctuate, pigment dispersion varies, leading to color drift. Additionally, the carrier resin in solid masterbatch may undergo thermal degradation during extended high-temperature residence, further affecting color uniformity.

Liquid color contains pigments that are already fully dispersed before entering the equipment, eliminating the need for shear-dependent dispersion. The pigments simply mix uniformly into the melt, delivering stable color throughout the run. In long production runs, liquid color maintains consistent color from start to finish and across batches.

For industries with strict color consistency requirements—such as automotive interior components, medical devices, and food packaging—this characteristic is a key reason for choosing liquid color.

Differences in Let-Down Ratio

Solid masterbatch typically requires a let-down ratio of 2% to 4%. For every ton of product, 20 to 40 kilograms of masterbatch must be added. A substantial portion of this is carrier resin, which serves only as a vehicle for the pigment and contributes nothing to product performance.

Liquid color, with its higher pigment concentration and superior dispersion efficiency, often achieves the same opacity with a let-down ratio of just 0.03% to 1.5%. A lower let-down ratio brings multiple benefits: reduced material costs, lower inventory requirements, and lighter shipping weight.

Feasibility of Switching to Liquid Color

A common concern about switching to liquid color is whether it requires costly equipment modifications or complicates operations. In practice, most existing equipment does not require major changes. Only a small metering system—similar to those already used for additives in many factories—needs to be added to enable seamless operation.

Each coloring solution has its own characteristics. Factories should evaluate them based on their product requirements, production patterns, and cost structures.

Liquid color offers clear advantages in several areas by changing the physical form and delivery method of the colorant. For operations that involve frequent color changes, demand high color consistency, and prioritize production cost management, liquid color is a worthwhile option to consider.