What grade of anodic coating is required for outdoor coastal applications?

Grade AC 25 (minimum average thickness of 25 microns) is recommended for severe marine and industrial environments.

What is the minimum coating thickness for general exterior use?

Grade AC 15 (15 microns) is generally required for normal outdoor architectural applications.

How is the sealing quality of the anodic coating tested?

Through methods like the chromic-phosphoric acid dissolution test or dye absorption test, as specified in IS 5523.

IS 2848

: 1997

Anodized aluminium for architectural purposes - Specification

CurrentFrequently UsedSpecificationBIMArchitectural · Aluminium and Non-Ferrous Metals

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This standard specifies the requirements for anodic coatings on aluminium and its alloys used for architectural purposes. It defines coating grades based on thickness, sets criteria for sealing quality, and outlines testing procedures to ensure long-term durability against weathering.

Lays down requirements for anodized aluminium and its alloys specifically for architectural applications.

Quick Reference Values

Grade AC 10 minimum average thickness10 microns (interior use)

Grade AC 15 minimum average thickness15 microns (normal exterior use)

Grade AC 20 minimum average thickness20 microns (aggressive exterior use)

Grade AC 25 minimum average thickness25 microns (marine/severe industrial use)

Practical Notes

Always define acceptable color variation limits using physical limit samples before mass production, as batch-to-batch variation in color anodizing is common.

Ensure the correct specification of coating thickness grade (e.g., AC 25 for coastal areas) to avoid premature fading, staining, or pitting corrosion.

Sealing quality must be strictly verified; poorly sealed pores are a primary cause of rapid finish degradation and surface blooming.