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Materials
Tray, syringe with 5 mL water, 1 Multifiber 6 ( 5 cm x 5 cm), black TDK CD-R PEN.
Experiment
1. Mark the 6 fabrics of Multifiber 6 (Diacetate, cotton, polyamide, polyester, polyacrylic, wool) using the black CD-R PEN (Fig. 1).
2. Drop water below the numbers on each fabric.
3. Compare the time needed by each fabric to absorb water drops.
4. Add drops until the whole multifibre fabric is wet.
Observations
1. In fabric 1 (diacetate), 2 (cotton) and 5 (polyacrylic) the water drops disappear immediately after adding (Fig. 2).
Polyester (4) and polyamide (3) are following. Wool takes the longest time to be saturated with water).
2. The water entering the fabrics separates a red substance from the black marker.
The better the water can penetrate the fabric (5 and 1) the clearer this effect can be observed (Fig. 3).
Explanation
1. The fabrics are made of very thin fibres which leave space between each other. These absorb the water penetrating from the drops on the surface of each fabric.
2. There can be different reasons for the speeds of absorption: One might be the chemical properties of the fibres.
The repulsion of the water drop by wool (Fig. 3) is due to the fat lanolin covering the fibers.
3. The black colour of the CD-R Pen is a mixture containing a red substance with limited solubility in water.
The separation of the red colour is an effect known as chromatography. It will be repeated and explained in the next experiment.