AATCC 179 (AATCC: American Association of Textile Chemists and Colorists) is used to determine the change in skew (or distortion) after home laundering. The change is skew, or torque or distortion; its calculated value is never negative but always positive. Skew plays a vital role in both knitted and woven fabrics and garments. It’s usually applied in garments and bedding.
The AATCC 179 test is performed under specific conditions such as controlled temperature and humidity. In this method, a testing specimen is marked and laundered. After laundering and conditioning, a formula is applied to determine the skew value. Controlling skew or distortion is very important for the good quality and attractive appearance of the woven or knitted garment, and it should be controlled in the initial stages before stitching.
Apparatus for AATCC 179
- The conditioning room should have a controlled temperature of 21±2 degrees centigrade and humidity of 65±5 RH as per the AATCC conditioning requirement.
- A permanent ink maker should mark the specimen.
- A marking template should be used to mark the testing specimen. The marking template should be square, and each side of the square should be the same length.
- Measurement tape to measure the size of the testing specimen before and after home laundering.
- Washing machine for recommended home laundering temperature and cycle. The machine cycle and the temperature of the washing cycle should be selected per customer testing protocols.
- AATCC 1993 standard reference detergent. With OBA and Without OBA will depend on the colour of the testing specimen. Usually, OBA is used for white articles, and Without OBA is used for dyed articles.
- Weighing balance with at least 5kg capacity. You must weigh the testing specimen and ballast (Dummy weight) to make it around 1.8 kg.
- Laundering ballast to fulfil the required weight and its type A and type will depend on the nature of the testing specimen.
- The testing specimen should be dried in a tumble dryer at the temperature recommended on care labels or according to customer testing protocols.
Preparation of Testing Specimen for AATCC 179
If the sample is fabric
- Take almost 3 samples from different rolls of the same lot. 3 testing specimens will provide an accurate percentage of skew.
- Cut the testing specimen at least 15×15 inch. Cover both lengthwise and widthwise direction of the fabric.
- Mark it lengthwise on the fabric’s front side. For marking, a marking template must be used to mark the same length of each size of the s
If the sample is a garment
- Randomly select garments from the testing lot.
- Take almost 3 garments from the lot. 3 testing specimens will provide an accurate percentage of skew.
- 0 Mark lengthwise on the garment. A marking template must be used to mark the same length of each size of the square.
Marking of testing specimen
- Lay the specimen on the smooth and flat working table free from tension.
- Mark 10 inches with the template and write A, B, C, and D on the corner of the square.
- Write A、B、C and D should be clockwise and start from the lower lift corner.
- For circular knitted fabric, Use the tube form and for others, use an open form of the fabric.
Washing Method
- Select the number of washes and temperature as per customer protocol.
- Put the testing specimen in the washer and add enough ballast to make a total load of 1.8±0.1 kg
- Start the DaRong Washing machine and allow it to fill with the required amount of hot and cold water to bring the required washing temperature.
- Add 66±0.1 g AATCC 1993 standard reference detergent as directed by DaRong washing machine instructions.
- After completing the washing test, separate the ballasts and test the specimen.
- To dry the testing specimen, put it in a DaRong dryer and set the drying temperature according to the care label.
- After completing the drying process, Keep the testing sample in a conditioning room with controlled temperature and humidity.
Measurement after conditioning:
- Measure and record the diagonal length between AC & BD after laundering.
- Calculate the percent change in skew by applying below formula
X= 100-[2 (AC-BD ) / (AC+BD ) ]
OR
[ (AC-BD) / (AC+BD)] X 200
Where X= % change in skew.
Conclusion
The AATCC 179 testing method plays a vital role in the textile industry, where skew can significantly affect the appearance of knitted or woven fabric or garment. The primary purpose of this method is to determine the per cent skewness in fabric or twist in garments after home laundering. It is applied on both knitted and woven fabrics & garments. Without controlling skews in fabrics, garments are reshaped, especially in knitted jersey fabrics. This test helps identify skew issues in fabric, which can be resolved by the compactor machines during the finishing process. Skew causes critical issues in printed shirts, garments, bed sheets and pillowcases. Controlling skewness if essential for good quality products.
FAQs
What is AATCC 179?
AATCC 179 is the test method for determining the percentage of skewness in woven or knitted fabric or garments.
Is AATCC 179 applied in home textiles?
Yes, this method is applied in home textiles. In-home textiles, this method is used to find changes in skew or distortion in bedding, such as bed sheets and pillow covers, curtains, and upholstery in knitted or woven articles.
Which machine is used to control skew?
A compactor is used to control skew in textile industries. In the finishing stage, the temperature and running time of the compactor are kept ideal to prevent skewness, which causes problems in knitted articles and printed articles.
Is this method applied to both fabric and garments?
Yes, this method applies to both fabric and garments, but the manufacturer should control skew or distortion on fabric to avoid skew or distortion on ready garments. It’s very difficult to control skewness or distortion in garments due to stitching, which will create puckering issues after home laundering. It won’t be easy to bring a smooth and attractive appearance.