Determination of pHof Fabrics or Garments

by usingGB/T 7573-2009 pH Test Method

Md.Azmir LatifMSc.inTE

Introduction: The pH of a solution is a measure of the molar

concentration of hydrogen ions in the solution and as such is a measure of the acidity or basicity of the solution.

pH is the negative logarithm of the hydrogen ion activity in a aqueous solution. The letters pH stand for "power of hydrogen" and the numerical value is defined as the negative base 10 logarithm of the molar concentration of hydrogen ions.

pH =-log10 [H+]

pH Scale:

• Range of pH scale: 0-14• pH = 7 equates pure water and / or neutral solutions• pH < 7 equates a solution with acid impacts• pH > 7 equates a solution with basic impacts

GB/T 7573-2009 pH Test Method:

Standard Number: GB/T 7573-2009

Title: Textiles Determination of pH of aqueous extract

Language: Simplified Chinese or English

Publication Date: 2009/6/11

Execute Date: 2010/1/1

Equipment Required for pH Test:

Glass flask, with a capacity of 100 ml.

Mechanical Shaker, providing rotational or reciprocating movement at a rate of 60/min.

Beakers, chemically resistant, with a capacity of 150 ml.

Glass rods, chemically resistant.

Volumetric cylinder with a capacity of 100 ml.

Hanna pH meter, with a glass electrode, capable of measuring to at

least 0.01 pH-units.

Electronic balance, accurate to 0.01 gm.

Preparation of Test Sample:

• Cut the laboratory sample into pieces having approximately 5 mm X 5mm so that allow the test samples to wet out rapidly.

• To avoid contamination, handle material as little as possible. Take from the laboratory sample three test samples.

• Weight accurately all three specimens in an electronic balance to 2.00 ± 0.05 gm each.

Preparation of Aqueous Extract:

• Place each test sample into 100 ml of extraction solution.

• Potassium chloride solution (KCI) into a stopper flask. Agitate the flask for a short period by hand to ensure that the textile material is properly wetted out, than shake it mechanically for 2 h ± 5 min.

• Record the temperature of the extracting solution used.

Measurement of the pH of the Aqueous Extract:• Calibrate the pH meter use a buffer solution with a pH of

7.0, a buffer solution with a pH of 4.0 at the temperature of the extract to be measured.

• Check the calibration of the pH meter. Immerse the electrode several times in the same solution (KCI) used to prepare the extract until the indicated pH value stabilizes.

• Decant the first extract into a beaker, immediately immerse the electrode to a depth of at least 10 mm and stir gently with a rod until the pH value stabilizes (do not record the pH value of this solution).

• Decant the second extract into another beaker, immediately immerse the electrode, without washing, in the beaker to a depth of at least 10 mm and allow to stand without stirring until the pH value stabilizes. Record this value.

• Decant the third extract into another beaker, immediately immerse the electrode, without washing, in the beaker to a depth of at least 10 mm and allow to stand without stirring until the pH value stabilizes. Record this value.

• Record the pH values of the second and third extracts as measurements.

• If the different between the two pH values, expressed to the nearest 0.1 pH value, is greater than 0.2, repeat the procedure other test samples. When tow valid measurements have been obtained, calculate the mean value.

Data:

SL Temperature Recorded pH value Mean pH value

1 27°C 6.5 6.6

2 27°C 6.7

Comments:pH value is to test the acid and alkali contents remained in apparel fabrics. Apparel fabrics which can directly contact with the skin have a relatively higher requirement on pH value. pH value will not make the skin itchy if controlled between weak acid or neutrality. This test method determines the pH of wet processed textiles.To make a quantitative determination, the chemicals which influence pH must be removed from the textile specimen, collected as a water extract then accurately measured by a pH meter. The various chemicals and processes in the textile and garment production, as well as in garment washing and finishing, will affect the final pH value.

Minimum Buyer requirement of Ph

Buyer- Obaibi/Okaidi

Buyer- H&M

Buyer- Carrefour

Thanks To All