Seiketsu

Seiketsu, often translated as standardization, is the fourth pillar of the 5S methodology, a system used to organize workplaces for efficiency and safety. The term is associated with maintaining cleanliness and order by standardizing the best practices established in the first three S: Sort, Set in order, and Shine. Seiketsu focuses on codifying these practices so that activities are performed consistently regardless of who does them.

The core idea of Seiketsu is to implement standardized procedures, visual controls, checklists, and routines that sustain the improvements achieved through the earlier steps. Common tools include standardized work instructions, color-coding schemes, labeling systems, routine cleaning and inspection schedules, and other visual cues that signal correct practice.

Implementation typically involves documenting the preferred method for repetitive tasks, training workers, and establishing regular audits or self-inspections to verify adherence. When gaps are found, corrective actions are taken and standards are updated through a PDCA (plan–do–check–act) cycle. Benefits include reduced process variation, faster onboarding, improved quality and safety, and easier problem identification, as predictable methods enable quicker response to deviations.

Seiketsu is widely applied in manufacturing and is also used in healthcare, offices, and service industries to sustain orderly workplaces. Critics note that excessive rigidity in standards can hinder creativity, so standards should be treated as living documents that evolve with continuous improvement.