GUT ODOUR TEST

 
 
 
Odours may impair the consumer’s well-being substantially. Therefore, the only odour that may be emitted by the product tested, is a characteristic "newness" odour of low intensity. Only such products are awarded the GUT Label.
 

Although the perception of odour is subjective and subject to fluctuations, the test method used here, in spite of its simplicity, is excellently suited for the assessment of textile floorcoverings.

Like other olfactory tests, the odour test for textile floorcoverings is conducted with a group of test persons specially trained for this method. In a worst-case scenario, the olfactory method for textile floorcoverings tries to simulate the odour development at increased temperatures (direct exposure to sunlight, floor heating). For this purpose, a 144 cm2 sample is thermostated for 15 hrs in a 2l desiccator at 37° C and 50 % relative humidity. After this conditioning and at 30 minute intervals, the team of test persons will individually assess the resulting odour development and will try to define the type of odour as well as the intensity and the overall impression.
It is the primary objective of such an odour test to ensure a clear distinction between acceptable new-product odour (= grade 3) and unacceptable odour formation (= grade 4).
 







 
Odour assessment of a sample that failed the test
Time Test person Type of odour Assessment Grade
8:00 Person 1 sweetish slightly unpleasant 3
8:30 Person 2 chemistry, aromatic unpleasant 4
9:00 Person 3 chemistry unpleasant 4
9:30 Person 4 aromatic unpleasant 4
10:00 Person 5 pungent, chemistry unpleasant 4
10:30 Person 6 sweetish unpleasant 4
11:00 Person 7 sweetish, chemistry unpleasant 4
Evaluation as median: sweetish, chemistry,aromatic unpleasant 4
Evaluation as mean value:     4




 
Odour assessment of a sample that passed the test
Time Test person Type of odour Assessment Grade
8:30 Person 1 fusty smell, new-product odour slightly unpleasant 3
9:00 Person 2 new-product odour slightly unpleasant 3
9:30 Person 3 fusty smell not unpleasant 2
10:00 Person 4 old slightly unpleasant 2,5
10:30 Person 5  new-product odour not unpleasant 2,5
11:00 Person 6 new-product odour not unpleasant 2,5
11:30 Person 7 fusty smell not unpleasant 2
Evaluation as median: new-product odour not unpleasant 2,5
Evaluation as mean value:     2,5

 



Test method:
The test is conducted in compliance with the Swiss standard SNV 195651 for the determination of nasal nuisance through textiles.
For a period of 15 hours, a sample of 144 cm2 is stored in an air-sealed desiccator (volume about 2l) at 37 °C and 50% relative humidity. In the process, the humidity is adjusted by means of a saturated magnesium nitrate solution (approx. 100 ml).

Under these conditions, at least seven test persons will subsequently open the desiccator for a brief moment and assess the intensity of the odour perceived. The intensity of the odour is graded by means of a scale from 1 (no odour formation) to 5 (very strong odour formation). When a test person has made his or her assessment, the desiccator must be sealed again and stored under the conditions indicated for at least another 15 minutes. When the test has been completed, the desiccator is left open at 37 °C until its interior is odour-free; if necessary, the salt solution must be renewed.

Grades
1 = no odour      2 = not unpleasant     3 = slightly unpleasant     4 = unpleasant 
5 = very unpleasant 
( Intermediate values like 1,5; 2,5; etc. are possible )

The mean value of the grades for the odour intensity must be a grade <  4.

 

 
In the future, it may be possible by means of so-called “electronic noses” to add an objective component to the subjective odour test.





"Electronic noses":

“Electronic noses” are analysers for the objective measurement of volatile compounds in the gas space above the sample to be assessed. “Electronic noses” deliver a fingerprint of the volatile components irrespective of whether or not these are odour-active. The difference between the human and the electronic nose is, however, in the different sensitivity towards volatile compounds. The correlation of the human odour perception with the chemical sensor signals may mean a major progress in the development of “electronic noses”.

 
GUT: carpets tested for a better living environment