Phthalocyanine pigments — the blue and green organic pigments most widely used across industry — have real baseline optical and water-repellent properties even before any surface treatment, and research measuring those baseline properties shows exactly how much room silica coating leaves to improve on them. This page covers that baseline data and phthalocyanine green’s narrow, specific FDA regulatory status.
What is it?
Organic pigments in this class are phthalocyanine blue and green colorants used across paints, coatings, plastics, and inks. Per 21 CFR §73.3124, phthalocyanine green (CAS Registry No. 1328-53-6, Colour Index No. 74260) is permitted by the FDA specifically as a color additive in contact lenses, in amounts not exceeding the minimum reasonably required for the intended coloring effect, and is exempt from certification requirements; this authorization is narrow and does not waive separate medical device requirements under the Federal Food, Drug, and Cosmetic Act, and does not apply to general industrial uses of the pigment.
Why should I use it?
- Even without surface treatment, phthalocyanine pigments have measurable baseline solar reflectance and water-repellent properties — see “How it’s used.”
- Phthalocyanine green has a specific, defined FDA color-additive status for one particular application, contact lenses — see “What is it?” above.
How it’s used
In paints and coatings, phthalocyanine pigments are used for solar-reflective and weather-protective formulations. A 2021 peer-reviewed study measured the baseline optical properties of untreated copper phthalocyanine pigment before applying a silica coating: total near-infrared reflectance of the untreated pigment was 36.4% for the green variant and 40.9% for the blue variant, with water contact angles of 113.3° (green) and 71.6° (blue).
Limitations — when it isn’t the right choice
- Untreated phthalocyanine pigment’s baseline solar-reflective and water-repellent performance is well below what’s achievable with surface treatment — plain pigment may not be enough for demanding reflective-coating applications. The same 2021 study found that applying a silica coating raised solar reflectance at 450-540 nanometers by 76.5% to 98.3% for the green pigment, and by 40.0% to 61.5% at 380-530 nanometers for the blue pigment, with near-infrared reflectance rising by a further 10.6% and 11.5% respectively; water contact angle rose to 154.4° (green) and 142.9° (blue) after coating. This means that for applications specifically demanding high solar reflectance or strong water repellency, untreated phthalocyanine pigment alone is unlikely to match a properly surface-treated grade, and the choice should be based on the specific coating’s performance requirements rather than assumed from the base pigment’s color properties alone.