GB/T 40936-2021Leather - Physical and mechanical tests - Determination of water repellency of garment leather (English PDF)

3.1 Spray rating

The degree of the water repellency of a leather surface.

5.5 The die knife shall meet the requirements of QB/T 2707, and the inner wall shall be

a square with a side of (182+/-2) mm.

5.6 Balance shall be accurate to 0.001 g.

5.7 The distilled water or the deionized water shall be in line with the provisions of the

third-grade water in GB/T 6682.

5.8 Filter paper or other equivalents shall be prepared.

6.1 Sampling

Carry out in accordance with the provisions of GB/T 39364. If it is not possible to sample from standard parts (such as sampling directly from clothing), it shall be taken from any part of the sample’s available surface. The samples shall be representative and indicated in the test report.

6.2 Preparation of samples

Use a die knife to cut out 3 square samples with a side of (182+/-2) mm; ensure that there are no holes, folds, creases, or other damages on the samples.

Note 1: When testing sheep leather with wool, in order to clamp the sample firmly, the wool can be sheared off.

Note 2: If there are more than 2 pieces of leather in the same batch to be tested, cut one sample from each piece of leather to be tested, and the total number of samples shall not be less than 3.

6.3 Samples’ adjustment in the air

Carry out in accordance with the provisions of QB/T 2707; weigh the sample after adjustment, and the mass shall be accurate to 0.001 g.

6.4 Test conditions

The test shall be carried out at a temperature of (20+/-2) °C or (23+/-2) °C. There are no requirements for humidity.

mw --- The amount of water absorbed by the sample, in grams (g);

m2 --- The mass of the sample after testing, in grams (g);

m1 --- The initial mass of the sample, in grams (g).

Calculate the water absorption rate of the sample w according to formula (2); use the arithmetic mean of the three samples’ water absorption rates as the result, and it shall be accurate to 0.1%.

Where:

w --- The sample’s water absorption rate (%);

mw --- The amount of water absorbed by the sample calculated according to formula (1), in grams (g);

m1 --- The initial mass of the sample, in grams (g).

9 Test report The test report shall contain the following:

a) The number of the document;

b) The detailed information of the sample; if the sampling is inconsistent with GB/T 39364, explain the situation;

c) The test conditions (standard atmosphere: 20 °C/65%, 23 °C/50% or 27 °C/65%);

d) The spray rating of each sample (7.4);

e) The wetting status of the back of the sample’s test surface (7.5);

f) The amount of water absorbed by the sample mw;

g) The water absorption rate of the sample w;

h) Any deviation from the provisions of this method;

i) Anomalies in the test.