Sanforizing Compression from Belt Geometry

Utilisation is the one soft input and it stands in for everything the model does not describe: fabric-to-belt friction, the moisture in the cloth entering the shoe, the penetration setting, the pressure on the compression roller and the condition of the belt surface. It is not a dial on the machine but a fitted number, and the way to get it is to run a known fabric and back-calculate. Once fitted on a construction it transfers reasonably across similar cloths and not at all between, say, a light poplin and a heavy denim. The model treats residual shrinkage as potential shrinkage less applied compression, which is a good first approximation and slightly optimistic: compression that exceeds what the yarn structure can absorb is not stored, it is simply lost, so a heavily over-compressed cloth does not go negative in the way this arithmetic suggests. It will instead grow in wash. Nothing here covers the weft direction, which is controlled by overfeed and the stenter rather than by the belt, and nothing covers the drying and setting that follow - a cloth compressed correctly and then dried under tension gives the shrinkage straight back, which is the most common reason a correctly set sanforizer still fails a wash test.