How to read an HVI report
The HVI (High Volume Instrument) report is the common language between cotton sellers and spinning mills. Here is what each line means and what to check.
Key parameters
- Micronaire (Mic): fineness and maturity of the fiber. Values of roughly 3.5 to 4.9 are commonly accepted. Very low values mean fine, immature fiber; very high values mean coarse fiber.
- Length (UHML, in mm or inches): the upper half mean length. Longer fiber allows finer and stronger yarn.
- Uniformity index (UI, %): the ratio of mean length to upper half mean length. A higher value means fewer short fibers.
- Strength (g/tex): bundle strength. Around 29 to 30 g/tex and above is generally considered strong.
- Elongation (%): how much the fiber stretches before it breaks.
- Color (Rd and +b): brightness (reflectance) and yellowness, often shown as a color grade code.
- Trash (count, area % or leaf grade): the amount of non-lint material in the cotton.
What to check before you buy
- The report matches your lot: lot and bale numbers, test date and the laboratory.
- Look at the spread, not only the average. A good average can hide weak bales.
- Compare every value with the specification in your contract.
- Ask for independent re-testing of samples from the lot if the order is large.
How East Cotton helps
East Cotton supplies cotton fiber with official HVI reports and can arrange independent sampling and re-testing before shipment.
General guidance. Tolerances and limits are always set in your contract.