Contamination through Stitching

The Problem

Every filter cloth used in Nutsche filters, centrifuges, and filter dryers must be shaped — cut to size, folded, and joined at seams. Traditionally, this is done by sewing: industrial sewing machines punch hundreds of needle holes through the fabric and pull thread through each one.

This process creates multiple contamination vectors: needle fragments can break off inside the fabric, thread fibres shed during filtration, and the needle holes themselves create uncontrolled leak paths that bypass the filtration surface. In pharmaceutical GMP production, any of these constitutes a batch contamination event.

Regulatory inspectors increasingly flag sewn filter cloths as a contamination risk in API manufacturing. The industry is moving toward joining technologies that eliminate thread and needle contact entirely.