The Comparison of Different Measuring Methods for Ph Value of Textiles

(1)Chinese standard（GB/T 7573-2009）
Weigh 3  2 + 0.05g samples, cut into 5 * 5 mm pieces, add put it into the flask containing 100ml distilled water,  shake flask, the samples will be fully soaked, put the flask on the oscillator for 2 hours ±5min, test the pH of aqueous extract (excluding fabric ) at room temperature, and repeat for 3 times, take the average values of the second and third samples as a result of the final results, accurate to 0.1.

(2) EU standards (EN 1413-1998)
Weigh 3 2 + 0.05g samples, cut into 5 * 5 mm small pieces, and put into flask containing 100ml of potassium chloride solution (0.1mol/L) or 100ml distilled water. and shake flask samples to make it fully soaked, put the flask on the oscillator for2 hours.  Test the pH of aqueous extract (excluding fabric ) at room temperature, and repeat for 3 times, take the average values of the second and third samples as a result of the final results, accurate to 0.1.

(3) Japanese standard (JIS, L, 1096-1999)
Weight 5 + 0.1g samples, cut into pieces of 1 * 1mm, and boil in 50ml distilled water and keep 2 minutes. Put the sample into the flask and shake flask and make the samples fully soaked at room temperature, and set aside for 30 minutes, remove the specimen. When the temperature of the water extraction liquid reached to 25 - 2 ℃, directly test the water extract with pH meter pH, accurate to 0.1.

(4) United States Standards (AATCC 81-2001)
Weighing 10 + 0.1g samples, cut into pieces, boiled in distilled water and keep 10 minutes, Put the sample into the flask, and shake the samples until it is fully soaked, continue to boil for 10 minutes, cooling to room temperature, remove the specimen, direct test the pH value of water extraction liquid, accurate to 0.01.

Standard	Standard name	Sample weight/g	Size/mm	Extraction reagent	Extraction methods	Extraction time/min
China	GB/T 7573-2009	2±0.05	5×5	100ml distilled water	Shake at room temperature/3 samples	60
EU	EN 1413-1998	2±0.05	5×5	100ml patassium Chloride Solution or 100ml distilled water	Shake at room temperature/3 samples	120
Japanese	JIS L 1096-1999	5±0.1	1×1	50ml boiled distilled water	Boiled and stay/1 sample	30
UAS	AATCC 81-2001	10±0.1	Norequirement	250ml boiled distilled water	Boiled /1 sample	10

The PH value of water extract liquor for fabric in different testing standard

Sample	the PH value of the same sample in different standard
	China	EU	JAPAN	America
1# White	7.10	7.2	8.3	8.52
2# gray	7.00	7.1	8.5	8.76
3# blue	6.70	7.0	8.1	8.14
4# Red and white squares	6.50	6.7	7.3	7.47
5# Dark blue	7.20	8.0	8.8	9.20
6# coffee color	6.70	6.9	8.4	8.56
7# dark blue	7.10	7.2	8.2	8.31
8# black	8.40	8.60	9.10	9.2

Tips
The above different test standards and different test results for the same sample show that: there must be standard requirements for a different standard.

Questions: Why are the same specimens tested several times with different results?
Answers: This result is from testing instruments, operating and environmental errors, and testing the error of distilled water, so it is recommended that the fabric manufacturer is tested at the regular inspection facility.

How should we deal with is if the pH unqualified textiles are tested?

If the fabric or garment detected pH unqualified, we usually need to adjust the fabric pH through the principle of acid-base neutralization. PH is probably not qualified alkaline, many kinds can be used to regulate the acid, the most common is acetic acid and citric acid. The acetic acid is volatile and has irritating odor, The citric acid is used to adjust pH is stable, so we general use of citric acid to regulate, but we should pay attention to control the amount. Overdose will affect the hand feel, and it is easy to cause yellowing.

For example: if the fabric measured pH value is 9-10, you can adjust the citric acid water solution pH value to 4-5, and then soak for 10 minutes to dry. Send it to formal inspection Institute and inspected qualified before it is sent to the customers and reduce trade risk.