As may be seen from the photos, the water drops on the siliconized surfaces and the card coated with candle wax form fairly spherical droplets and do not spread out. Viewed from the side, the drops on the treated surfaces are much higher than those on the untreated surfaces.

 The water on the siliconized surfaces is absorbed much more slowly than that on the untreated surfaces. It is not possible to calculate the contact angle with the naked eye.

The water drops on the surfaces treated with glycerol spread out extensively and are quickly absorbed. Thus, the water-repellency of a copper panel that has been thoroughly cleaned with ethyl alcohol is substantially reduced by glycerol. In contrast, the silicone fluid actually increases the water repellency.

 The card coated with candle wax is water repellent because the candle wax is actually solid paraffin wax, i.e. it is a mixture of saturated aliphatic hydrocarbons. These are nonpolar molecules that, like the methyl groups in the silicone fluid, have hydrophobic properties. They interact very weakly with the water molecules and so the water stays in the drop and does not wet the paraffin wax.
Paraffin wax is considered to be the most hydrophobic water-repellent agent. However, paraffin waxes do not adhere as well as silicone fluids to surfaces made of stone, glass or paper, and can be scratched off.
Another major advantage over paraffin waxes is that silicone films have a very low surface tension, a fact which makes them highly spreadable and which enables hydrophobic effects to be achieved with much smaller quantities. Unlike paraffin waxes, silicone fluids have hardly effect on surface properties, such as their appearance and “ability to breathe.”

The increase observed in the hydrophilic properties of surfaces treated with glycerol may be explained in terms of the structure of glycerol. The glycerol molecule C₃H₅(OH)₃ has three hydroxyl groups that form hydrogen bonds with water molecules. Glycerol can therefore be mixed in any proportion with water.

• Use a camera to calculate the contact angle accurately. The contact angle can be calculated fairly accurately with the aid of a computer.
• Color the water droplet with methylene blue dye to accentuate the contours of the water droplet and to make observations easier. That will greatly help determining the contact angle with the aid of the camera.
  The silicone fluid can be baked into the glass and then rubbed off with a paper towel so that the coating is almost invisible. Nevertheless, the water-repellent effect can still be observed.
  Baking can be done by thoroughly cleaning the silicone-treated glass and dry heating it at over 100 °C for 15 to 20 minutes.
• A qualitative version of the experiment (without a camera) is easy and quick to perform. The experiment is thus ideal for demonstrating the water-repellent properties of silicones, and especially of silicone fluids. Qualititative determination of the contact angle with a camera is fairly time-consuming and offers little in the way of new insights, as the result can be interpreted qualitatively.
• Comparing the molecular structures of silicone fluid, glycerol and paraffin wax is a very good way of explaining the different properties. This affords a good way of incorporating the important relationship between a material’s particle structure and its properties into the lesson.
• In secondary school chemistry classes, the experiment could be used, for example, to cover the terms hydrophobic and hydrophilic. It could also be used as part of a project.
  Advanced chemistry students could draw on their knowledge of particle structure and properties (water repellency of alkanes) to interpret the results and deepen their understanding. In the construction industry, the water-repellent property of silicone fluid is a key element of monument conservation ("Silicones for construction")
• Since the experiment is safe and simple, it is ideal for the classroom. To save time, the pupils should be divided into groups, with each group investigating a different surface.