How to Determine the Color Fastness of Textile material to Dry Cleaning
1.To determine colorfastness to drycleaning a suitable mechanical device consisting of water bath containing a rotatable shaft which supports, radially, glass or stainless steel containers ( 75+-5mm diameter x 125+-10mm high) of approximately 550+-50 ml. capacity, being 45+-10mm high from the centre of the shaft should be used. The Shaft/container assembly is rotated at a speed of 40+-2 rev per minutes.The temperature of the water bath is thermostatically controlled to maintain the test solvent at 30 deg +-2 celcius.
2. Stainless stell disc of 30+-2mm x 3+-0.5mm, smooth and free from rough edges of mass 20+-2 gm.
3. Undyed cotton twill cloth of unit area 270+-70 gsm, free from finishing and cut into samples of size 12 cm x 12 cm
4. Grey scale for evaluating change in color and staining.
5. Glass tubes of diameter 25 mm
Preparation of the Specimen
For a fabric sample, take a specimen of size 10cm x 4cm from the sample representing the lot.
If the material to be tested is sewing thread, make a wick of parallel length 10 cm long and about 0.5 cm in diameter, tied near both ends.
Prepare a bag with inside dimension of 10cm x 10 cm using the undyed cotton twill cloth by sewing together two squares of this cloth around three sides.
Place the specimen and 12 stell discs inside the bag and close the bag.
Place the bag in the container and add 200 ml of Perchloroethylene or any other suitable solvent at 30 +- 2 deg C
Fix the container in the mechanical device maintained at 30+-2 deg C and run the machine for 30 minutes.
Remove the bag from the container, withdraw the specimen and dry the specimen in air at a temperature not exceeding 60+-5 deg C.
Evaluate the change in color of the tested test specimen with grey scale, after attaining normal moisture content.
Filter the solvent remaining in the container through filter paper and compare the color of the filtered solvent with that of unused solvent in the glass tube placed in from the white card using transmitted light by means of grey scale for assessing staining.
In case of doubt in the color fastness rating as assessed by an observer, the assessment should be done by at least three observers and the overall average rating should be reported.
Report the numerical rating for change in color of the test specimen and the numerical rating for staining of the solvent. Also report the solvent used for the test.