Tarpaulins are generally categorized into two main types: coarse tarpaulins and fine tarpaulins.
Coarse tarpaulins (also known as covering tarps) are made of tough, crease-resistant fabric with excellent water resistance; they are used for covering cargo during truck transport and in open-air warehouses, as well as for pitching tents in the field.
Fine tarpaulins are used to manufacture protective workwear and related gear. After dyeing, the fabric can also be used for shoes, travel bags, and backpacks. Additionally, there are specialized tarpaulins such as rubberized tarpaulins, fire-resistant and radiation-shielding tarpaulins, and tarpaulins used in papermaking machinery.
1. Yarn Count:
Simply put, yarn count refers to the thickness or fineness of the yarn. China commonly uses the "Imperial system": if one pound (454 grams) of cotton yarn (or yarn of other compositions) measures 840 yards in length, the yarn fineness is defined as "1 count" (1S). If one pound of yarn measures 10 × 840 yards, the fineness is 10 counts (10S). In the Imperial system, the symbol "S" denotes the count. Single yarn is designated as follows: 32-count single yarn is written as "32S". Plied yarn (twisted strands) is designated as follows: 32-count plied yarn (two strands twisted together) is "32S/2"; 42-count yarn with three strands twisted together is "42S/3".
2. Density:
The unit of measurement for tarpaulin fabric density is metric, referring to the number of warp and weft yarns arranged within a 10 cm span. Density directly influences physical and mechanical properties-such as appearance, hand-feel, thickness, strength, crease resistance, breathability, abrasion resistance, and thermal insulation-while also impacting product cost and production efficiency.
Indirect Testing Method
This method is suitable for fabrics with high density and fine yarn counts that feature a regular weave structure. First, the fabric weave and the number of warp yarns (or weft yarns) in the weave repeat are analyzed; this figure is then multiplied by the number of weave repeats within a 10 cm span to obtain the warp (or weft) yarn density.
Direct Counting Method
The direct counting method is performed using a cloth inspection glass or a fabric density analysis glass. The scale on the fabric density analysis glass is 5 cm long. Beneath the lens, a red line is etched onto a strip of glass. To analyze fabric density, position the lens so that both the red line on the glass strip and the red line on the scale align with the space between two yarns; using this as the starting point, count the yarns while moving the lens until the 5 cm mark is reached. Multiply the counted number of yarns by 2 to obtain the density value for a 10 cm length of fabric.
When counting the yarns, begin at the midpoint between two yarns. If the count at the endpoint exceeds 0.5 yarns but is less than a full yarn, it should be calculated as 0.75 yarns.
If the count is less than 0.5 yarns, it should be calculated as 0.25 yarns. Generally, 3 to 4 measurements should be taken, and the arithmetic mean of these values used as the final result.
3. Gram Weight:
Gram weight refers to the weight in grams of one square meter of fabric.
Woven tarpaulin fabrics are often specified in ounces ("oz"), while knitted tarpaulin fabrics typically use gram weight (g/m²). The conversion rate is 1 ounce to 28.375 grams, though fabric-weighing machines typically use a value of 28.35 grams. This measurement depends on yarn count and fabric warp/weft density; the coarser the yarn and the higher the density, the thicker the fabric and the greater the gram weight.
