Lab 3: Chromatography

Original design

1. It is important for only the wick and not the filter paper circle to make contact with the water because if the water traveled directly through the paper, the water would douse the paper and not flow through it. Because different inks have different physical characteristics, they were able to be moved at different rates through the paper and produce different pigment bands. If the water was left on the paper, the ink would've left the paper simultaneously and would've been washed from the paper, still as a mixture.

2. Several variables that affected the color pattern on the filter paper were the types of pens we used, the thickness of the pen nib, the location of the markings on the paper, the amount of ink on the paper, and the amount of time the paper was left on the wick. 

Wick inserted into the center

3. The ink separated into different pigment bands because of the inks' different physical properties. Some inks had physical properties that allowed them to travel up the filter paper more quickly, creating the bands that were farthest away from their original ink marks. Others had physical properties that made them move more slowly, which made the bands closer to the original ink location. 

4. Blue is present in several of the ink samples. This blue pigment throughout the different ink samples appears to be identical. This specific color of blue appears in all of the samples, which indicates that the pens used and their respective ink contain the same pigment of this shade of blue. 

5. The pens used in this experiment needed to be water-soluble so that the inks could be lifted up by and travel through the water and therefore produce pigment bands on the filter paper. If this experiment was to be done with permanent ink, it would be necessary to use a different medium instead of water in the cup and wick. 

Side view of the wick
and water cup

Final product!