Precise Pigment Dosing in Molded Pulp: Achieving Batch-to-Batch Color Consistency

Colored molded pulp fails customers when shade drifts between batches, and manual pigment dumping is the usual culprit. A controlled dosing system — gravimetric feeders, metered pigment slurry, and inline color measurement — locks pigment addition to within a tight tolerance, delivering batch-to-batch color consistency that passes brand Delta-E limits.

The Scenario: Color that must not drift

Colored pulp production faces three challenges:

Pain Points

• Manual pigment dumping varies from operator to operator, drifting shade between batches;
• Brand customers hold suppliers to tight Delta-E color tolerances that manual dosing cannot meet;
• Rework from off-color batches wastes pigment, fiber, and drying energy.

The Solution: Three pigment dosing solutions

A controlled dosing system offers three fixes for colored pulp:

1. Gravimetric pigment feeders Gravimetric feeders dose pigment by weight, eliminating operator-to-operator variation.

2. Metered pigment slurry Pre-dispersed pigment slurry is metered inline, so color concentrates evenly through the furnish.

3. Inline color measurement Inline color sensors feed back to the doser, auto-correcting shade to stay within Delta-E limits.

The Result: Color locked batch to batch

With these controls, colored pulp holds consistent shade batch to batch, cutting rework and passing brand color audits.

Sources & Evidence

• Molded pulp is colored with water-based dyes or pigments metered into the slurry during stock preparation. (Source: TAPPI / molded-pulp coloring references)
• Mold release agents are applied to molded-pulp tooling to prevent sticking and extend tool life. (Source: TAPPI / molded-pulp manufacturing references)