A titanium dioxide pigment with an oil absorption value of 14 is not necessarily easier to formulate than one with a reported value of 19. Before comparing those numbers, buyers need to establish how each supplier measured them.

Oil absorption is a useful property when evaluating titanium dioxide (TiO₂) pigments for paints and coatings. It helps indicate how a pigment behaves when mixed with a liquid under defined laboratory conditions. However, differences in testing methods, reference oils and reporting units can make two apparently precise results difficult to compare.

A 2026 update to the international oil absorption standard makes this a timely documentation issue for purchasing and quality teams. The practical solution is to compare results on a common testing basis before treating numerical differences as evidence of better pigment performance.

What Titanium Dioxide Oil Absorption Actually Measures

Oil absorption describes the quantity of oil needed to bring a measured amount of pigment to a defined paste consistency under a specified test procedure.

The result is commonly expressed as grams of oil per 100 grams of pigment or millilitres of oil per 100 grams of pigment. These units are different and must be identified before comparing results.

For coating manufacturers, oil absorption can provide useful information about pigment wetting characteristics and the approximate liquid demand of a pigment paste.

It may also help formulators investigate differences in surface treatment, particle characteristics or production consistency.

However, oil absorption does not directly establish how much commercial binder a paint formulation will require.

Linseed oil used in a laboratory test does not behave identically to every acrylic, alkyd, epoxy or other coating binder. The relationship between a measured oil absorption value and finished-paint performance depends on the complete formulation.

A lower oil absorption value is therefore not an automatic guarantee of lower viscosity, better dispersion, improved hiding power or reduced manufacturing cost.

Why Different Testing Methods Produce Different Results

Two established ASTM methods illustrate the problem.

The ASTM D281-12(2021) oil absorption method determines pigment oil absorption using a spatula rub-out procedure. It is intended to provide information about a pigment’s liquid demand under the prescribed test conditions.

The ASTM D1483-12(2023) Gardner-Coleman method uses a different incorporation approach. Instead of vigorous rubbing, it relies on gentler stirring and folding.

Because the methods use different working actions and endpoints, their results generally differ. A value determined by one method should not be treated as directly equivalent to a value produced by the other.

For procurement teams, this creates a straightforward risk.

Supplier A might report an oil absorption value obtained using ASTM D281, while Supplier B provides a value measured using ASTM D1483.

If both technical data sheets display only the heading “Oil Absorption,” the numbers may look directly comparable even though they were produced using different procedures.

The problem is not necessarily inaccurate testing. It is incomplete reporting.

A meaningful comparison needs the test method, method edition, result units and relevant testing conditions.

ISO 787-5:2026 Adds a Document-Control Check

The International Organization for Standardization published ISO 787-5:2026, Determination of Oil Absorption Value in April 2026.

This second edition replaced ISO 787-5:1980, which ISO now identifies as withdrawn.

The published scope describes a general test method for determining the oil absorption value of pigments and extenders. It also emphasizes comparison with an agreed reference sample tested at the same time.

This is useful for chemical manufacturers and buyers working across international supply chains.

A purchasing specification may still reference the 1980 edition, while a laboratory or supplier has moved to the 2026 edition.

That difference should trigger a controlled review rather than an automatic acceptance or rejection.

The publicly available ISO summary establishes the change in edition and status. It does not establish which detailed procedural requirements or numerical outcomes changed between editions.

Teams should therefore examine the applicable standard text before concluding that historical and newly reported results are interchangeable.

A practical document review should establish whether the supplier’s laboratory method, customer specification and incoming-inspection procedure refer to the same edition.

Historical results can remain useful for tracking previous production lots, but their testing basis should be preserved.

A Real Supplier Data Sheet Shows Why Method Details Matter

The difference between reported and comparable values is not merely theoretical.

Chemours publishes a technical data sheet for Ti-Pure TS-6706 titanium dioxide, a rutile pigment intended for coating applications.

The document reports a typical oil absorption figure of 13.9.

Its footnote explains that Chemours uses a linseed oil with an acid number of approximately 12 under its own testing method. It contrasts this with the oil specified in the older ASTM D281 edition referenced in the sheet.

The supplier also provides a conversion relationship:

ASTM-equivalent oil absorption = Chemours oil absorption × 1.35

Applying the manufacturer’s stated factor to its published typical value gives:

13.9 × 1.35 = 18.765

That is approximately 18.8 on the conversion basis described in the document.

The difference between 13.9 and 18.8 is about 35% of the original numerical value.

Yet the calculation does not demonstrate a change in the underlying pigment.

It demonstrates how the reported result can depend on the supplier’s testing and conversion convention.

There are important limits to this example.

The conversion factor belongs to this particular manufacturer’s published method comparison. It should not be applied automatically to another titanium dioxide grade or supplier.

The data sheet also identifies the 13.9 result as typical rather than a guaranteed minimum or maximum. Its displayed property table does not explicitly state the oil absorption unit, so buyers should confirm the reporting unit directly.

Finally, the document refers to an older ASTM edition. Its conversion statement should not be treated as proof of compliance with every provision of the currently active ASTM method or the new ISO edition.

How Buyers Should Compare Titanium Dioxide Grades

A dependable comparison begins with a common test method rather than a common-looking number.

Procurement and quality teams should request the exact oil absorption method and edition used by each supplier, together with the reporting unit and any modifications to the standard procedure.

If suppliers use different methods, ask whether they can provide results obtained through a shared recognized procedure.

Independent laboratory testing may be appropriate when oil absorption is a critical acceptance parameter or when supplier methods cannot be reconciled confidently.

The next step is to establish whether the comparison concerns different commercial grades or different production lots of the same approved grade.

For lot-to-lot monitoring, the most useful reference is often the established performance range of an approved material measured consistently over time.

For alternative-grade qualification, oil absorption should be considered alongside other application-relevant properties.

These may include particle-size distribution, surface treatment, moisture, dispersion behavior, viscosity development and finished-film opacity.

The broader guide to titanium dioxide specifications explains how these properties contribute to pigment qualification and supplier comparisons.

A technical data sheet can describe typical characteristics, but it is not the same as an agreed purchasing specification.

Likewise, a certificate of analysis reports supplier test results for an identified lot. A safety data sheet communicates hazard and safe-use information. Neither document independently proves that a pigment will perform successfully in a particular coating formulation.

Where acceptance is commercially important, the purchasing specification should define the agreed limits, testing procedure, reporting basis and change-control expectations.

Independent tests can provide additional confirmation, but their scope, methods and sample representativeness still need examination.

Oil Absorption Should Support Formulation Testing, Not Replace It

Consider two titanium dioxide grades intended for the same waterborne architectural coating.

One supplier reports lower oil absorption than the other. After checking the laboratory procedures, the buyer establishes that both results were obtained using equivalent methods.

That comparison is now more meaningful, but it still does not settle the grade-selection decision.

The paint manufacturer needs to know how each pigment behaves in the intended formulation.

Controlled comparative trials can examine whether the grades meet targets for dispersion, viscosity, opacity, gloss and coating stability.

Those tests should use consistent formulation conditions and documented evaluation procedures. Qualified laboratory personnel should determine the appropriate methods, safety controls and acceptance criteria.

A grade with a favorable oil absorption result may still require changes to the dispersant package or fail an essential appearance requirement.

Another grade with a higher result could perform acceptably because its surface treatment and particle characteristics suit the binder system.

The commercial question is not which pigment produces the smallest oil absorption number. It is which approved grade delivers the required finished-product performance consistently and economically.

A Better Oil Absorption Specification Prevents False Comparisons

Oil absorption is most valuable when suppliers and buyers agree on what the number represents.

For future purchasing documents, define the test method, edition, units, acceptance criteria and reference material where appropriate. Keep historical results traceable to their original methods instead of converting old data without a validated basis.

The April 2026 ISO revision provides a practical reason to review outdated references, particularly where several suppliers or laboratories contribute to the same quality system.

A supplier’s numerical advantage should not become a purchasing decision until the comparison is technically valid.

That single verification step can prevent unnecessary supplier disputes, misleading quality trends and expensive formulation trials based on measurements that were never directly comparable.