Optical Brighteners for Plastics: Selection and Trials

Optical brighteners change the perceived whiteness of a material through fluorescence. Select a plastic optical brightener for the resin, processing conditions and lighting under which the finished product will be evaluated. A brighter laboratory plaque under one light source does not establish the same appearance in every application.

Whitening is a different task from stabilization

The existing research describes differences between polymer hosts. That is a reason to test the actual resin and formulation rather than selecting only by additive name. If the problem is degradation during processing or outdoor service, investigate antioxidants or UV stabilizers as appropriate; perceived whiteness does not by itself prove that degradation has been controlled.

BASF’s Tinopal overview presents named brighteners for different applications. Product-family branding is not evidence that a detergent brightener or coating grade is suitable for a particular plastic process.

Screen the candidate for the actual application

For resin background, read PP or PET. These links explain material families; they do not certify an additive grade for them.

Include lighting in the trial

Milliken discusses PP appearance under different lighting. Use this as a reason to define how the product will be viewed and measured. Its commercial clarifier discussion does not prove that every brightener will behave identically, or establish the superiority of a product in your formulation.

ASTM E313 is the existing reference for calculating whiteness and yellowness indices. Record the instrument method and measurement settings alongside specimen thickness, formulation and processing history. Keep the control specimen so later lots can be compared under the same conditions.

A controlled color and processing comparison

Obtain the candidate TDS and SDS, including processing and addition guidance. Compare a control formulation with defined candidate levels within that guidance. Check shade and uniformity, as well as the properties required of the finished product. Do not publish a universal dosage from a study performed in a different polymer.

The previously cited polymer-host study supports treating the resin as part of the experiment. Its results concern the tested systems, not an automatic selection rule for all formulations. For color changes that may originate in compounding or molding, see color-masterbatch matching across processes.

Check end-use documentation independently

For a contact-use application, request the grade-specific documentation and assess testing for the actual polymer, concentration and use conditions with the responsible technical team. A migration result for one additive and package cannot be generalized to every optical brightener. The existing research citation is an example of why test conditions matter, not a commercial approval.

Share resin, process, current formulation, appearance target, viewing conditions, end use, quantity and destination when discussing a candidate. This is a reference selection guide; commercial availability and suitability need confirmation separately.

Content reviewed: 8 October 2026. BASF and Milliken sources are linked above; existing ASTM and polymer-host/migration research references remain in the technical-reference section.