QC (Quality Control)
The checks a factory or buyer performs on materials, production, and finished goods to make sure products meet the agreed specifications.
TL;DR: QC is the set of inspections and tests used to confirm that products meet the agreed standard. In manufacturing, it usually happens at several stages, from raw materials to finished goods.
Factories often describe QC in stages. IQC (incoming quality control) checks raw materials and components when they arrive. IPQC (in-process quality control) checks work during production, so problems are caught before a whole batch is affected. FQC (final quality control) or OQC (outgoing quality control) checks finished, packed goods before they leave the factory.
QC is sometimes confused with quality assurance (QA). QC focuses on inspecting products and finding defects. QA is broader and covers the systems and procedures that prevent defects in the first place.
A factory’s internal QC is important, but buyers often add their own checks. Common options include approving a PPS (Pre-Production Sample), a PSI (Pre-Shipment Inspection), and hiring a Third-Party Inspection company. Sampling plans based on AQL (Acceptable Quality Limit) define how many units to check and how many defects are acceptable.
The most useful QC starts with clear specifications. Write down what matters, such as dimensions, color tolerance, surface finish, packaging, and labeling, and agree on it before production. For custom mosaic work, useful checks include color against the approved sample, sheet numbering against the layout, mesh or paper backing adhesion, and chipped or cracked tiles.