Dosage rate is one of the first questions a converter has to answer when specifying a masterbatch, and it’s also one of the easiest to get wrong. Too low, and you don’t hit target opacity, color strength, or performance. Too high, and you’re paying for material you don’t need – or worse, introducing processing problems the base resin was never meant to handle.

The right dosage rate depends on what the masterbatch is doing. For a white masterbatch built on titanium dioxide, dosage typically falls between 3% and 20%, and the right point within that range depends on the opacity and brightness your finished part needs to hit. A thin blown film that needs full opacity at a low gauge will sit at the higher end of that range; a thicker injection-molded part that only needs a bright, consistent white can often run leaner.

For color masterbatches, the range is usually 1% to 5%, and it’s driven by pigment concentration rather than opacity alone. A high-pigment-load formulation lets you run a lower dosage rate for the same color strength – which matters if you’re trying to control cost per part without compromising on shade consistency. This is also where carrier resin compatibility becomes important: a pigment dispersion built for PE won’t necessarily disperse the same way in PP or ABS, so dosage recommendations are always tied to the base resin you’re actually running.

Filler masterbatches work differently again. Here, dosage is less about visual performance and more about the cost-versus-mechanical-properties trade-off. A calcium carbonate filler masterbatch might run at higher loadings – 70% to 85% filler content within the concentrate – specifically because the goal is to displace virgin resin cost-effectively while keeping impact strength within an acceptable tolerance band.

Processing additives are the exception to the “more is better for performance” instinct – these are typically dosed lean, often 1% to 3%, because the active ingredients (UV stabilizers, slip agents, antioxidants) work at low concentrations and over-dosing rarely improves the effect; it just adds cost and can sometimes interfere with other additives already in the resin system.

The practical takeaway: dosage rate isn’t a single number you look up once. It’s a function of your target opacity or color strength, your carrier resin, your process (film vs. molding vs. extrusion behave differently), and your cost targets. That’s why we don’t publish a single “recommended dosage” – we work through it with each converter based on their actual process and specification, usually starting with a trial batch at the low end of the range and adjusting from real production data rather than a lab estimate alone.