Functional Pigment Selection for Coatings: Colour, Hiding and Protection
Specify colour, hiding or protection separately, then agree a grade-specific coating trial before ordering pigment samples.
Specify what the pigment must do before comparing grades: deliver a colour, hide the substrate, produce an optical effect or contribute to corrosion protection. These functions can require different materials and acceptance tests. The MOS coating pigment catalogue includes colour and anticorrosive pigment families. A catalogue entry helps shortlist a sample; it does not establish performance in your coating.
Separate pigment identity from the required function
An organic-versus-inorganic comparison is a useful starting question, but it is not a universal ranking of durability, opacity or suitability. Ask for the exact grade and relevant Colour Index designation. Different grades in the same chemical family can have different optical properties or surface treatments. Heubach’s technical pigment literature distinguishes grade-level transparency, opacity and application suitability; those properties must be checked for the actual material offered, rather than transferred from another supplier’s data.
An anticorrosive pigment is not qualified by its colour match. Evaluate it in the intended primer and substrate system, with an agreed protection test. SNCZ’s waterborne primer examples use specified binders, substrates and film conditions. Their reported results do not constitute a guarantee for a MOS-supplied material or your formulation.
| Required function | Procurement question | Trial evidence |
|---|---|---|
| Colour / tinting | Exact grade, colour reference and sample-lot identity? | Agreed colour method and reference film, including a white reduction when relevant |
| Hiding / transparency | Opaque finish or translucent/effect design? | Drawdown on the agreed substrate at a defined dry-film thickness |
| Protective function | Which primer, substrate and exposure are intended? | System-specific protection test and acceptance criteria |
| Formulation compatibility | Binder, waterborne/solventborne system and incorporation route? | Agreed dispersion, stability and film-quality checks |
| Lot consistency | Which specification and COA fields will be supplied? | Sample-to-reference comparison using agreed methods |
Make the sample comparison fair
Equal pigment weight does not necessarily mean equal pigment volume when densities differ. Record whether a comparison holds pigment mass, volume or an agreed optical result constant. Ask for the density or solids basis needed for the calculation; do not infer it from a generic family name. Binder demand and formulation balance also need review before a substitution.
Use the accepted grade as a control. Record binder, dispersion method, sample lot, substrate preparation, application and cure conditions, and dry-film thickness. Agree which tests answer the buying question, then compare on that basis. A colour match alone does not qualify weathering or corrosion performance. Review the binder category and supporting coating additives if the trial changes the formulation; their compatibility and incorporation conditions still require confirmation.
Check documents before approving a replacement
Request the current offered-grade TDS and SDS, proposed specification and available lot COA fields. Confirm the supplied form, surface treatment where applicable, storage/handling guidance and destination-specific requirements. Keep catalogue heat-resistance values, dosage suggestions and environmental labels out of a purchasing specification until the supplier confirms their basis and applicability. A successful sample does not establish every regulatory approval or unrestricted transport status.
Send a pigment RFQ with the acceptance brief
Start from the pigments and functional materials category. Provide the application, binder and waterborne/solventborne system, current pigment/grade, required colour and hiding or protective function, substrate and film conditions. Include the comparison basis, critical tests, sample quantity, order quantity and annual demand, preferred packaging and destination. Request current TDS/SDS, agreed COA fields and confirmation of the offered grade. This gives procurement and technical teams a common basis for quotation and sample acceptance.
Pigment procurement FAQ
Does Colour Index prove two grades are interchangeable?
No. Confirm the exact grades and relevant optical, surface-treatment and application data, then qualify the replacement in the actual coating.
Are inorganic pigments always more durable than organic pigments?
No family-wide rule qualifies a grade. Review grade-specific data and the required film, substrate and exposure tests.
Can equal pigment weight be used for every trial?
Do not assume so. Different densities can change pigment volume and formulation balance. State the comparison basis and agree the calculation and tests.
What should accompany a pigment sample request?
Application and binder, current grade, required function and colour reference, substrate/film conditions, acceptance tests, quantities, packaging, destination and TDS/SDS/COA requirements.