Filament length, torsional rigidity, fineness, uniformity and cross sectional shape are critical factors for rope strength. The higher the grade, the longer and stronger the fibers. Impurities are a weak point.
Bangladesh and India use different systems e.g. BTS (Bangla Tossa Special), BTA etc. are paper trading grades. With the advice of the National Jute Laboratory, we aggregate grading thus:
Grade 1: uniform golden to reddish with the finest structure, min. filament 1.5m very strong and very good lustre, completely free of defects and blemishes, no breaks, dark bark, waste, specks, cuttings or habijabi tangles.
Grade 2: uniform silver gray to golden with fine structure, min. filament 1.25m, strong and good lustre, completely free of blemishes.
Grade 3: clean, sound, light/medium gray to copper-ish gray, good texture, fairly strong and good average lustre, min. filament 1m, free of blemishes.
Grade 4: mixed colors, fair to average strength, occasional bark and soft specs but free from runners, min. filament length 0.75m, slightly cropped and gummy tops permissible, free of black wiry tops and root ends.
Grade 5: average color and strength, min. filament unspecified, occasional bark and speck, croppy and gummy tops permissible, but free of black root ends and runners.
Quality is strength. Analyze and grade your own rope. Take a length and unwind the strands of yarns.