Interesting Phenomenon

[KingRoach]

 

I'm mixing my own colours. I keep samples in these small airtight lab tubes. I kept this small amount overnight with the tube standing upright. Next day, the ink is still sloshing all over the tube, but it seems like some of it is "stuck" to the walls of the tube.

 

Is this surface tension from the tube? I believe if I keep it upside down, the amount WILL eventually go down, and will not stain. I was actually worried about it staining my pens, but having tried it, it doesn't.

 

Any inky thoughts?

[amberleadavis]

I think it is called Adhesion.

 

Surface Tension

There is a force of attraction between molecules in liquids, and liquids can flow until they take on the shape that maximizes this force of attraction. Below the surface of the liquid, the force of cohesion (literally, "sticking together") between molecules is the same in all directions, as shown in the figure below. Molecules on the surface of the liquid, however, feel a net force of attraction that pulls them back into the body of the liquid. As a result, the liquid tries to take on the shape that has the smallest possible surface area http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/em.gif the shape of a sphere. The magnitude of the force that controls the shape of the liquid is called the surface tension. The stronger the bonds between the molecules in the liquid, the larger the surface tension.

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/graphics/14_9fig.gif

There is also a force of adhesion (literally, "sticking") between a liquid and the walls of the container. When the force of adhesion is more than half as large as the force of cohesion between the liquid molecules, the liquid is said to "wet" the solid. A good example of this phenomenon is the wetting of paper by water. The force of adhesion between paper and water combined with the force of cohesion between water molecules explains why sheets of wet paper stick together.

Water wets glass because of the force of adhesion that results from interactions between the positive ends of the polar water molecules and the negatively charged oxygen atoms in glass. As a result, water forms a meniscus that curves upward in a small-diameter glass tube, as shown in the figure below. (The term meniscus comes from the Greek word for "moon" and is used to describe anything that has a crescent shape.) The meniscus that water forms in a buret results from a balance between the force of adhesion pulling up on the column of water to wet the walls of the glass tube and the force of gravity pulling down on the liquid.

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/graphics/14_10fig.gif Water climbs the walls of a small-diameter tube to form a meniscus that curves upward, whereas mercury forms a meniscus that curves downward.

The force of adhesion between water and wax is very small compared to the force of cohesion between water molecules. As a result, rain doesn't adhere to wax. It tends to form beads, or drops, with the smallest possible surface area, thereby maximizing the force of cohesion between the water molecules. The same thing happens when mercury is spilled on glass or poured into a narrow glass tube. The force of cohesion between mercury atoms is so much larger than the force of adhesion between mercury and glass that the area of contact between mercury and glass is kept to a minimum, with the net result being the meniscus shown in the above figure.

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/property.php

[Chrissy]

I have seen this happening with many of my sample vials. I have also found that the ink doesn't stain my barrels any more or less than any other inks though.

[Arkamas]

I get it as well in my vials. Pretty normal.

[KingRoach]

Good to hear. I only ever had glass bottles and never saw this happening this way.

 

What I found strange was that, ink would slosh around and not stick to the walls at all. It would only stick if left overnight, and then if left in a different direction, the stuck inks would loosen and go elsewhere, but also after a while. It is a slow process.

[Pensei]

Thanks for that post, amberleadavis. Reading it felt a bit like being back in school, but it was interesting.

[amberleadavis]

Thanks for that post, amberleadavis. Reading it felt a bit like being back in school, but it was interesting.

 

 

LOL, I agree. I'm not a chemist so would generally say that it sticks to the walls of the vials. What you may not realize is that on the first fills of a new converter, adhesion often occurs.