# Knowledge of woven fabric (part 3) – The importance of mass

Fabric weight is the weight of fabric per unit area, usually grams per square meter (g / m2 or grams per square meter GSM) or Ounces per square yard (Ounce per square yard – Oz / yd2) commonly used used in international measurement systems.

A fabric called lightweight when the weight ranges from: 30 -150 g / m2; Called average when weight ranges from 150- 350 g / m2; And called heavy fabric when weight more than 300g / m2.
Typically, the weight of the fabric must be described in both GSM g / m2 or Metric units and also the Imperial (Imperial) measurement system meaning Oz / Yd2 because:

Metric is the ISO standard unit used in the international standard ASTM D3776-07 for the determination of material weight per area. When you send the fabric to a testing lab, they will use this standard to check and report the results.
The tool for checking weight by this method is simple, turn money and can be done right in your office.
Although the international standard, but the United States is one of the countries do not use this metric, so must turn into Oz / Yd2.
In addition, sometimes people also describe the weight of fabric in units of its length (Linear measure). For example:

g / m or gram per 1m length (g / m or gram per linear meter)
oz / yd or ounces per yard in length (oz / yd or ounces per linear yard),
1 Ounce = 28.35 grams

1 Yard = 0.914 meters

1 Square yard or Yd2 = 0.914 x 0.914 = 0, 836 square meters

So:

1 Oz / Yd2 = 28.35gr / 0.836 m2 = 33.9

Looking at fabric weight, weaving style and finishing, can help you to decide on the most appropriate fabric according to its end use requirements.

In apparel, people also rely on the weight of fabric or thick fabric to choose the appropriate sewing thread or sewing needle to match.

4 / Fabric composition (Fabric composition%):

Fabric composition is certainly an important parameter when describing or mentioning a particular fabric or garment. In addition to the fabric composition tells us the physical and chemical properties of the product, the level of value, the nature of use … it is also a mandatory requirement to publish on the label of goods in accordance with the law (for example such as regulation 16 CFR Part 303 of the US Federal Trade Commission or EU regulation 1007/2011 of the European Union …) to protect the interests of consumers.

These regulations generally oblige each textile product to be sold on the market when it is required to clearly indicate the composition of the textile material on the label of goods used, which shall include information on the textile material, instructions for use. Use, importer information, origin … and must be attached on the product during use with other requirements such as recognizable, easy to read … In addition, this component must be classified. analyzed and certified by an independent testing agency or laboratory, recognized by the government of the importing country. For example, laboratories Intertek, BV, SGS, TUV …

Many cases in the domestic market today, we encounter clothes that are obviously 100% Polyester, but on the component label, it is still 100% Cotton, or 65% polyester 35% Cotton … I do not think these are cases where the manufacturer deliberately deceives the user but is not aware of the important role, the meaning of the fabric component and has not been fully instructed on label requirements. components from responsible agencies.

So what is the fabric composition:

Fabric composition includes the proportion of fiber components involved in the fabric. It can be natural or man-made. It could be just one type of fiber (100%) or 2, 3 .. or maybe more different types of fiber. For example:

100% Cotton

Or: Cotton 60% Polyester 40%

Or: 65% Polyester, 31% Coton, 4% Spandex

………………………… ..

To determine the fabric composition one can use qualitative and quantitative analysis methods

Check visually or under a microscope.
By burning and recognizing the type of fiber.
Use chemical dissolution and recognize it based on the solubility characteristics of each fiber type.
Based on the specific optical spectrum of each fiber type.
Two standard methods for determining fabric composition in current testing laboratories such as Intertek, BV, TUV., SGS, etc. are used as standards:

AATCC 20A for qualitative tests and
AATCC 20 for quantitative testing. Example results in an ITS report are as follows:

By the way, this is only a brief overview of the classification of textile materials. To get a better understanding of the properties and applications of textile fibers, you will have to read more in the article that specializes in fine materials.