Absorbency Test Weighed sample

Dry Sample Weight g

With the sample area, this sets the basis weight: 0.45 g on 100 cm² is 45 g/m².

Saturated Weight g

A barrier fabric gains little; an absorbent dressing gains several times its dry weight.

Sample Area cm²

Barrier Hydrostatic head test

Hydrostatic Head cm H2O

Measured on the same fabric as the absorbency sample.

Absorbency Capacity

— %

Fluid held as a percentage of dry weight

Performance Metrics

Absorbency: — g/g
Absorbency per Square Metre: — g/m²
Basis Weight (from the sample): — g/m²
Hydrostatic Head: — kPa
Hydrostatic Head per Unit Weight: — cm per g/m²

Hydrostatic head per unit weight divides the head by the basis weight, to compare fabrics of different weight. It is not the Barrier Index of EN 13795-1, which is the result of the wet bacterial penetration test, EN ISO 22610. AAMI barrier levels are defined by hydrostatic head and impact penetration together. A single hydrohead figure does not classify a gown on its own. Strike-through time is a different test on a different specimen and is not used here.

Medical Nonwoven Absorbency & Barrier Calculator — free, with the formula and a worked example, at Textile School.