How do you calculate pigment usage in rotational molding?

Multiply the resin coverage by the pigment loading per unit, then divide by the transfer efficiency expressed as a decimal. With 500 units of coverage, 0.08 loading, and 85% efficiency you need 47.06 units of pigment versus a theoretical 40.

Why is my actual pigment usage higher than the loading rate?

Dry-blended pigment never fully transfers to the part. Dust, drum-wall adhesion, and fines lost at powder handling mean a chunk stays behind. At 85% efficiency that gap is about 7.06 units per batch, or a 15% loss allowance.

What is a good pigment transfer efficiency for dry-blend rotomolding?

Dry-blended color typically lands between 80% and 90% efficient. Precompounded or turbo-blended color can exceed 95%. If you're below 80%, look at blend time, pigment carrier compatibility, and drum contamination.

How much masterbatch should I order for a production run?

Use the required quantity, not the theoretical. For this batch you'd order against 47.06 units, then multiply by batch count and add a safety margin for setup purges and color changes.

Does this work for UV stabilizers and antioxidants too?

Yes. Any dry-added additive follows the same math. Set the loading per unit to the additive's dose rate and adjust efficiency, since fine powders often transfer differently than pigment flake.

How do I reduce pigment loss allowance?

Switch from dry-blend to precompounded color, extend and standardize mix time, keep drums clean between colors, and add an adhesion promoter or dispersant to the powder blend to raise transfer efficiency.

Rotational Molding calculator

Pigment/Additive Usage Calculator

Pigment and additive usage tells a rotational molder how much colorant, UV stabilizer, or antioxidant masterbatch actually has to be weighed out per batch, not just the theoretical loading rate on the spec sheet. Because dry-blended pigment clings to drum walls, dusts off during tumble-mixing, and never fully deposits on the part, the real draw always exceeds the theoretical figure. Process engineers and purchasing use this to size masterbatch orders, cost color, and avoid mid-run shortages on long production days. Getting it right keeps color consistent tank to tank and stops you from over-buying expensive pigment you'll never mold into a part.

What this calculator does

Pigment and additive usage tells a rotational molder how much colorant, UV stabilizer, or antioxidant masterbatch actually has to be weighed out per batch, not just the theoretical loading rate on the spec sheet.
Use it when pigment/additive usage in rotational molding needs a buy quantity for the next rotational molding run and you do not want to short the line.
It computes the actual pigment or additive weight you must charge per batch after accounting for transfer efficiency, plus the loss allowance over the theoretical amount.

Formula used

Required pigment/additive usage = covered amount × use per unit ÷ transfer efficiency
Loss allowance = required amount - theoretical amount

Inputs explained

Total part surface area or shot weight covered:
Pigment/additive loading per unit of resin:
Dry-blend transfer efficiency:

How to use the result

Use it when quoting a new colored part, ordering masterbatch for a run, or reconciling why your color usage runs higher than the loading rate suggests.
Transfer efficiency varies with pigment type, blend method (dry-blend vs. compounded), and drum cleanliness, so treat the single efficiency figure as a batch average, not a guaranteed per-part deposit.

Current U.S. benchmarks

The producer price index for plastic resins and materials stands at 319.371 (BLS, May 2026), up 19.5% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 9,635 plastics product manufacturing establishments employing about 677,302 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate pigment usage in rotational molding? Multiply the resin coverage by the pigment loading per unit, then divide by the transfer efficiency expressed as a decimal. With 500 units of coverage, 0.08 loading, and 85% efficiency you need 47.06 units of pigment versus a theoretical 40.
Why is my actual pigment usage higher than the loading rate? Dry-blended pigment never fully transfers to the part. Dust, drum-wall adhesion, and fines lost at powder handling mean a chunk stays behind. At 85% efficiency that gap is about 7.06 units per batch, or a 15% loss allowance.
What is a good pigment transfer efficiency for dry-blend rotomolding? Dry-blended color typically lands between 80% and 90% efficient. Precompounded or turbo-blended color can exceed 95%. If you're below 80%, look at blend time, pigment carrier compatibility, and drum contamination.
How much masterbatch should I order for a production run? Use the required quantity, not the theoretical. For this batch you'd order against 47.06 units, then multiply by batch count and add a safety margin for setup purges and color changes.
Does this work for UV stabilizers and antioxidants too? Yes. Any dry-added additive follows the same math. Set the loading per unit to the additive's dose rate and adjust efficiency, since fine powders often transfer differently than pigment flake.

Last reviewed 2026-05-12.