Chemie

pH value determination

PH value of aqueous extract

DIN EN ISO 3071 specifies a method for determining the pH value of textiles. A defined weight of the textile is poured into a defined volume of saline water and then the pH value of the aqueous extract is measured with the help of a pH meter.

Test description

The pH value is a concentration measurement of H3O+  (acidic) and OH- (basic). In neutral water, the pH is 7, at this point the concentration of the two molecules is the same). The lower the pH, the more acidic the water; The higher, the more basic. The conversion takes place via the negative decadal logarithm: A pH change of 1 is a 10 x higher or lower concentration. Since the skin has a natural acid protection and has a pH value of about pH 6, a pH value between 5 and 7 is considered optimal for textiles. Basic textiles (pH value > 8) can irritate the skin, very acidic textiles (pH value < 4) as well.

To determine the pH value, the acidic and basic molecules are extracted from the textile in water. The water is saline so that it is conductive. After extraction, the pH of the extract is determined. The process can be applied to textiles of all fibres and all shapes, whereby very voluminous fibre types such as cushion fillings or nonwovens can make extraction difficult. Water-repellent finishes can also falsify the measurement.

At CTL GmbH we determine the pH value between pH 2 and pH 13. As a rule, these limits are not exceeded or undercut in textiles.

Options

  • pH value of aqueous extract (extrapolation method) – Test method according to DIN 54275. The pH value is determined at a liquor ratio of 1:1 (50 g textile per 50 ml water). Since this is not directly measurable, different concentrations are measured and then extrapolated.
  • pH of aqueous solutions – Test method in which the pH of an aqueous liquid is determined directly.

Required material for the test

  • at least 7,5 g product weight

Additional Tips

Deviations in the pH value can be easily corrected by washing.

How do we work

Our workflow

01

Specifications

At the beginning, we clarify the scope of testing, the goal of the tests and, if applicable, the project requirements with the customer.

02

Offer

We prepare a quotation based on the scope of testing and the requirements

03

Test

The order is clear and as soon as the test sample is received in the laboratory, we get straight to work with the sample.

04

Submitted test reports

The results are available in the form of a test report. In addition to the pure test result, an overall assessment according to legal, general or customer-specific requirements is possible.

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