SNV 195 651 Textiles - Determination of Odour Extraction by Finishes

The standard “SNV 195 651 Textiles - Determination of odor extraction by finishes”, developed by the Swiss Association for Standardization (SNV), describes a procedure for evaluating odor behavior under the influence of temperature and climate.

Mainly textile-based upholstery emits a more or less perceptible odor after a while after being installed. This odor is the odor of the upholstery material itself and starts to decrease significantly and disappear after a while after the installation process. A similar odor is not only emitted in floor coverings, but also in beds, armchairs and sofas and large-covered products and disappears after a while.

It is possible to detect such odors and determine their quality with odor tests performed in advanced laboratories. One of the standards used in odor tests is the SNV 195 651 standard. In these tests, samples taken both at the time of delivery and after storage are analyzed by taking into account the parameters of temperature, humidity and time.

In the tests, the odor intensity is evaluated independently by at least six experts in this field. The following criteria are used in this evaluation:

• 1 = Odorless
• 2 = Weak odor
• 3 = Average odor
• 4 = Strong odor
• 5 = Very strong odor

Intermediate grades are often used during evaluation.

Fragrances used to remove oily, greasy or dye-based odors originating from the production processes of textile products or to add fragrance to these products are outside the scope of this standard.

Sensory measurements use the human nose as an odor detector and are directly related to the characteristics of odors experienced by humans. Essentially, sensory measurement techniques fall into two categories:

• Quantitative measurements combining the nose with some instruments
• Parametric measurements using the nose without any other device

Instrumental sensory measurements use the human nose in conjunction with a device called an olfactometer, which dilutes an odor sample with odorless air to precise ratios to determine odor concentrations. Variables that can affect olfactometric measurements include olfactometer design, test procedure, varying sensitivities of observers, data quality, and measurement uncertainty.

• Parametric sensory measurements have the advantage of being rapidly available at relatively low cost, as they do not require specific equipment. Special care must be taken in interpreting the results because of the variability in odor perception, even for well-trained personnel. Parameters that can be measured subjectively include odor character, odor intensity, and hedonic tone.
• Odor character, often referred to as odor quality, is a nominal measurement scale. Odors can be characterized using a reference dictionary, which is a standard list of descriptive terms. Perceived odor intensity is the relative strength of the odor above the threshold of recognition. Odor intensity is measured using a variety of methods, including descriptive category scales, magnitude estimation, and reference scales. There are a variety of scales, typically using 3–10 categories, and panelists must rate the intensity of the sample against the specified scale. The most commonly applied scale lists six categories, from no odor to very strong odor.
• Hedonic tone describes the pleasantness and unpleasantness of an odorant. A method for determining hedonic odor tone has been standardized. Dilutions are presented to panelists via an olfactometer. If the panelist detects an odor, the hedonic odor tone of the perceived concentration is rated on a category scale ranging from “extremely unpleasant,” “neither pleasant nor unpleasant,” to “extremely pleasant.”

Among the numerous tests, measurements, analyses and evaluation studies carried out for businesses in various sectors, our organization also provides testing services defined in the standard “SNV 195 651 Textile - Determination of odor extraction by finishes” with its trained and expert staff and advanced technological equipment.