Laboratory Apparatus
Precision comb beds mounted on a manual sorting frame extract and align individual textile fibres by length for staple analysis. Quality control laboratories rely on specialized mechanical sorters to construct physical fibre arrays from raw or processed flax samples. Operating the Johannsen comb sorter involves transferring tufts through parallel comb banks, aligning fibre bases along a zero baseline, and dropping successive combs to isolate specific length fractions.
Test reports document length distribution curves and short fibre percentages derived from the sorted arrays.
Array Preparation
Technicians prepare a representative sample by drawing tufts across primary and secondary comb sets, removing crimp and parallelizing filaments without causing manual breakage. Dropping individual comb bars exposes the longest fibre tips, which are pulled using padded gripping clamps and laid onto velvet boards in descending length order. The operator weighs each length fraction on an analytical balance, constructing a cumulative frequency curve of fibre lengths.
Precise alignment of fibre ends against the initial reference line ensures accurate determination of mean length and short fibre content. System errors arise if manual pull force varies during extraction or if pins bent during previous tests snag passing filaments.
Measurement Scope
Fibre arrays created by this device assess raw flax lot uniformity before spinning operations begin. The apparatus fails to yield reliable data when evaluating severely tangled tow fibres or un-retted stem fragments.
